And for good reason, quite often skimmer bodies are very thin to cut down on costs and acrylic can become more brittle from extended use.

Interesting but I see fish poop on the floor as simply fish poop on the floor. External skimmers can make a big mess which is why I see a pump as a clear advantage.

Well this thread is about skimmers and another discussion regarding turnover flow is currently taking place in another thread, I didn't want to be too repetitive but...
http://canreef.com/vbulletin/showpos...4&postcount=15
Basically I think it's fairly obvious that more return flow means more filtration. A sump is essentially a filter, bigger filters with more flow, filter more water quicker. A typical skimmer is independent from return flow and will essentially work the same regardless of return flow (in limits). Eliminating or reducing the need for additional power heads or closed loops is also a big plus in my book and I believe it results in a simpler system. You can increase in tank flow all you want but if you're limited by return flow your filter is also limited, higher return flow will not only keep particles and matter suspended but it will also filter them out faster. Not everything rises perfectly to the top of a tank and gets filtered out through the overflow in real life. Surface skimming is always going to be limited by blocks we install to prevent creatures from escaping and high total tank flow keeps things mixed up. I've also seen surface skum build up problems with lower flow tanks.

Well your science isn't that scientific, it's really just an opinion based on your own experiences and some information from various sources, just like mine.
To me turnover means the flow turned through the sump. Pure closed loop, in tank flow doesn't really turnover anything. I prefer to practice around 10x turnover with additional in tank flow if required, many times this is not required as tank demands are based on coral species kept. I've gone into as much detail as you have on this subject, perhaps it's split between two threads but it is there. The problem is it doesn't really mean anything without evidence to back it up which is why I for one look at other peoples experiences as well rather than being blinded by my own.

Well I for one do enjoy reading TOTM profiles, I think it's interesting to see what successful tanks use for equipment and I think a lot can be learned from other peoples experiences. Taking ideas from a group will almost always produce better results than taking ideas from one individual. I'm not sure why you would consider such a thing dishonest, perhaps the parameters aren't always that accurate but the equipment and healthy corals looks awfully real to me.

Why on earth would I deny that, of course progress exists. There's obviously more involved in these tanks but the maintainers of such aquariums seem to know what they're doing, if you want to believe it's just all luck and witchcraft that's your call.

Well I guess we're opposites which is probably why we get along so well :wink:, I consider myself smarter than I am experienced. I have an engineering degree and I believe I pick up things faster than most people. Where I lack personal experience I have to rely on other peoples experience to fill gaps when necessary.

I usually don't take things personally unless it's obvious it's meant to be. I've enjoyed our discussion so far and I'm here for the same reasons you are.
Cheers

Would definitely agree, reef tanks are more of an art form than a science. The science is the easy part but making it all come together is what makes or breaks a tank.

I don't know what you mean by "external skimmers". I assume it's a type of protein skimmer and not a surface skimmer.

I see sumps as a drip catcher for filtration devices, not as filters in and of themselves. Sometimes less is more. You never gave any reasoning or linked any sources for the 10x turnover you feel so strongly about. Why not 40x if you want to do it all with one pump? That way your drain will not need to be vented and you wont get the salt spray and suction sound. There has to be reasoning why a particular turnover volume achieves a dynamic equilibrium.

Very few if any protein skimmers cannot be operated on a two compartment FIFO system as I have described above. Even a becket skimmer with a high volume pump can be plumbed with the effluent line directed to a second compartment so skimmer treats new water first.

If you compare two scenarios with the first one delivering 2500 GPH to the sump drawn over a 12" x 6" overflow, then a second system where only 1000 GPH was drawn over the same overflow and delivered to a sump. The second scenario would have a higher concentration of surfactants due to a thinner film collected at the surface. It's the same argument one would make for a longer overflow box or removing the teeth from an overflow. Both scenarios keep the protein skimmer fed with fresh water. The first version moves some extra water that doesn't reach the protein skimmer. If you don't use a FIFO method, the 2500 GPH system will process the same water over and over with greatly diminished efficiency.

There are many ways to skim the cat, but you must use a method that assures that the protein skimmer is fed pre-skimmed (highly concentrated/protein-rich water) and skim it only once before returning it to the tank where it mixes with unfiltered water.

If your gola is to eliminate closed lops and power heads than you will need a 20x turnover rate, providing your flow dynamics are good, and they will be limited by only surface draining.

I wouldn't use teeth on an overflow for this reason. Horizontal barriers placed parallel to the overflow (above it) will keep out fish and inverts without breaking surface tension or reducing overflow surface area. Plastic gutter guard placed vertically inside an overflow box will serve the same purpose.

This is where a closed loop system offers superior flow dynamics. A return and intake can work together to build up inertia (kinetic energy). Closed loop intakes can be located in areas where detritus settles and inline mechanical filters can be used to collect it. Closed loops also offer a back-up system for flow (gas exchange) if sumps run dry, pump failure, or while you are servicing the filtration in the sump or feeding.

Using a one pump system with a 10x turnover ratio will not adequately keep detritus suspended, create ripples on the surface, keep the whole surface moving, and reach all parts of the reef structure.

It isn't really my science, I quoted a number of very reputable sources and I showed the math. You didn't explain your experiences and you didn't show the math or even a link to the source of your magic number of 10x turnover. If you need me to back up anything I have said with scientific information than I will be happy to. I am also willing to listen if you can find fault with any of the specifics of my logic.

The point her is simple. Why do you move water to and from your sump? The purpose is to give the filtration devices unprocessed water to clean. If your devices operate best at 3-5x the flow of the tank, then the other 5-7x you are moving is simply a juggling act. If our goal is to use our resources wisely, then we need to put more thought into magic numbers.

I appreciate that you have found this 10x formula to work best for you, but you don't have me convinced that you have had less success with 3-5x turnover or with a closed loop system (greater than 10x).

I treat TOTM's the same way I treat a show & shine car show. It's nice to see success and a well groomed finished product, but I prefer to follow the learning curve as the transmission comes out and you pass around the greasy factory manual as you come up with innovative modifications. I learn more from forum discussions about what does and doesn't work. I learn more from failures than triumphs, but it doesn't stop me from enjoying a mint TR6 :)

I would have gone easier on you if I had known you had an engineering degree working against you :)

I'm not asking you to explain the logic behind a 10x turnover ratio just to be a smart ass. I would like nothing more than to be proven wrong and learn something new. Heated debates on forums are my only chance to win an argument. I don't stand a chance with a debate with my wife :)

sphelps: I forgot to answer a question you asked earlier about posting my aquarium. I don't have one going right now, but I will be doing one in the January/February. I work in the aquarium industry, but mods frown on commercial posts so I don't post any pictures of my work unless they pertain to a specific question someone is asking.

I’m not quoting anything from previous posts because it’s starting to turn into meaningless debates and arguments. Simply quoting selective parts of a statement and arguing only with those parts is fairly meaningless and doesn’t present any new information but rather disagreements.

An external protein skimmer is a protein skimmer that works externally (not in sump). When someone refers to “recalculating protein skimmers” for the most part these skimmers are external models. In sump models are not usually recirculating unless modified by the owner.

Really the 10x flow rate rule is common knowledge; many basic guides to saltwater aquariums will state a total flow rate of 10 times the tank volume is a good rule of thumb. My way of thinking is to start with the minimum requirement, which I believe is about 10x, then supplement more if needed and of course only if it’s practical. Remember I’m not arguing the fact that 3-5x won’t work but rather than running 10x will also work, personally I believe it may work slightly better but that’s not my main argument. If a tank was small enough and it did require 40x turnover a single pump system could be very practical. For example if you had a 20 gallon aquarium you could push 800gph through the overflow if you wanted, it would be better in my mind than putting power heads in which would just clutter up a small tank. However I would never see the need to run that much turnover in most tanks, especially smaller ones and of course it’s simply not practical to use a single pump to push 4000gph in a 100gallon tank.
As requested:
I love how the term dynamic equilibrium was mentioned because in my mind it hasn’t really been considered. One theory states that with lower return flow you’re going to end up with a higher concentration of organics in the sump however this would only be true for the beginning of the cycle and if a build up exists. Once steady state is reached a tank shouldn’t have a build up of dissolved organics, the skimmer should have already taken them out and continues to do so as more are added. Now the other approach is higher flow but less concentrated so at the beginning of the cycle it may take longer to remove built up organics but once steady state is reached the results would be the same. I’ll try and explain this again in another way; if you have two skimmers and one that takes in a higher concentration of organics but these organics are supplied at a slower rate and the second skimmer takes in less concentration however it’s supplied at a faster rate. Once equilibrium is reached the results will be the same. A skimmer will only filter out a certain percentage of organics anyway and at the end of the day no matter what the flow rate through the sump a skimmer will eventually turn over all the water eventually either way. So on one hand we have a lower flow rate that could possibly have a higher concentration but takes longer to turnover the tanks volume and on the other hand we have a higher flow rate which could possibly have a lower concentration but turns over the tank volume faster. The way I see it, these are the same at equilibrium. It’s like walking a shorter distance compared to driving a longer distance; the question is what are the speeds and distances and which one is faster.

The last thing I’ll note on this is in regards to this so called higher concentration, is that this is not something I really buy and would be very difficult to prove either way. A lower flow rate may take a thinner layer and if there was a build up of organics the concentration would be greater however at steady state there wouldn’t be a build up, otherwise you would need a new skimmer. In addition while it may be true that organics rise that doesn’t mean all the dissolved organics are located at the very surface of the water. On top of that you’ve got tremendous amount water flow in the display so it’s not really realistic to say you’ll see a higher concentration of organics at the surface of the water. As long as you have surface skimming you shouldn’t see a build up over at steady state. This is especially true for dissolved organics, since you know, they are dissolved.

I understand the FIFO method approach but it can’t actually be pulled off. Even with a 3 times turnover on a 100g tank you’re taking about 300gph which is too much for a recalculating skimmer and any other skimmer (made for 100g tank) that pulls in that much water isn’t going to skim out 100% of the organics anyway so no matter what you going to get bypass, and then going back to equilibrium as described above you’ll end with the same results regardless.

I’m not sure what is meant by horizontal barriers so I can’t comment on how effective they are unless an example is provided but I know placing netting inside the overflow may prevent creatures from entering the sump but could still result in death, more than likely they will be stuck on the net and not be able to return to the tank on there own. It’s very simple to come up with a solution for anything and everything but if it’s not practical it’s not a real solution. Most tanks use a vertical guard on the overflow that disrupts surface skimming for obvious reasons.

While closed loops have advantages, again they are not always practical. A closed loop and inline mechanical filters will add complications most aquarists would prefer to avoid. Also closed loops are not much more efficient at creating flow as a return pump because the majority of head loss results from plumbing. Most aquarists would prefer power heads on most tanks; they are easier to maintain, easier to install, more efficient, and provide substantially more options for flow dynamics. With a good turnover rate and added “kinetic energy” :rolleyes: (which btw is related more to velocity than flow rate) from power heads you can filter out sufficient particulate matter without the use of complicated closed loops and mechanical filtration. Remember less is more ;)
Also in regards to efficiency this can be approached many ways however I will use my tank as an example. I run a return pump and two tunze power heads, if I drop a size in return pump I’ll save 17W and loose over 500gph, if I make that up with another power head how am I saving power? I’ll actually be using about the same but I’ve added more clutter, complication and maintenance to my tank. As stated my tank uses one return pump and two power heads, the return pump puts out about 1000gph with head and is rated at 65W (although I’m sure it’s using significantly less power) and my tunzes pulse so I’ll assume an average of 3000gph at 45W combined. That’s 110W or less for a 40X turnover on a 100 gallon tank. I’d like to see less power used and better flow on the same size tank using a smaller return pump and a closed loop. But I certainly wouldn’t want to see what it looks like.

I’m not looking for math or sources to back up claims, mainly because I don’t care that much but also because I’m not disagreeing. I know may people just love to argue but that’s not my goal here. Honestly you can use pretty much whatever flow you want for a sump turnover and my argument is that it doesn’t matter. Yes lower turnover rates are quieter and for this reason more common because higher flow rates require more experience to achieve quieter results. In addition lower flow rates require cheaper internal pumps; high flow pumps are more expensive and for the most part louder.

The two main arguments aren’t really that different, one argument is for 5x and the other is for 10x, however my argument isn’t really an argument. I’m not set in my ways but rather I believe advantages and disadvantages exist for both but really we’re not talking about a huge difference here. I’m going to say something and I honestly hope it doesn’t offend anyone but from my limited experience in both this hobby and my career, I have found that too much experience can be a bad thing. The main reason relates to the old saying, you can’t teach an old dog new tricks. This holds true in many cases, lots of guys I work/deal with are extremely reluctant to change and are set in there ways. Not that their ways are necessary bad but sometimes advancement and technology provides new opportunities and methods worth trying. For example how long have people been using the Herbie style overflow? Before this style of overflow it was virtually impossible to create quiet and bubble free high flow returns so nobody did it.

I’ve said it over and over again and feel now that I’m really beating it too death but a flow rate of 3-5x will produce success and so will 10-15x there really isn’t much of a difference. Skimmers are independent and other parts of the sump filtration need to be designed for a certain flow rate. What that flow rate is, is completely up to the owner’s or maintainer’s preference and there is no real scientific evidence to support either option.


Mr. Wilson, the way you compare TOTM to show n shines is completely irrational in my books. You can fake a car; it can be really nice but not work at all. Also they really only go together in one way until you get into customizing but the same rules apply. You can’t really fake success with a marine tank, you can clean it up a little but in the end you can’t fake it. In fact most will always say it looks better in person. Why do so many people now love using T5 lighting? I can guarantee you it’s because of all those beautiful European tanks. It doesn’t mean you’re guaranteed success and the same results by using them but it sure as heck shows they work. That’s my point with TOTM, sure nothing guarantees anything but if almost all successful tanks use something it probably works pretty good or at least you can’t say it doesn’t work.

Also I did see your webpage but was hoping to see something with a little less fluff. Not trying to prove anything but I was hoping to see examples of the filtration techniques you exercise and the mature tanks that prosper from it. I only ask out of curiosity as some of your techniques both scare and fascinate me. I can guarantee that Mods won’t object to you posting some pictures of your previous tanks, whether you owned them or not it wouldn’t be considered advertisement. Plus I’m sure after 30 years you’ve owned your fair share of aquariums.

I am not sure if you noticed, but if you continue to read the article from the magazine you quoted you will see the following, if you read further you might find that the writer is actually advocating against 10x through the sump rather 3x or 4x is better..

Yes I did notice, did you notice the reasoning (noise not performance) and the fact it has nothing to do with my argument or why I quoted that? Like I said before some just love to argue but I didn't say 3-5x was wrong just that it's not a requirement and 10x will work equally well if you can deal with the higher flow. Also note the date of the article.

You appear to be confirming your 10x turnover sump rate theory, however the article simply claims that 3x is adequate, otherwise they would have advocated a 10x capacity and explained how to select the correct size pipe for a silent overflow

Like I already stated, it takes more experience to run higher flows through overflows properly, it's not for everyone and it's not necessarily better than lower flow. That article is for beginners, which you would have noticed if you read the title rather than immediately trying to find something to argue with. I would never tell a beginner to use 10x turnover just like I wouldn't tell one to use a herbie overflow either.

You quoted the article to back up your statement, I am arguing no more than you are.

I have always promoted low flow, and have used syphon systems for many years, I have never advocated a Durso, a Durso is for people that have incorrectly sized their drains.

Please refrain from accusing me of making this a personal issue.

Perhaps you could read things properly before making your arguments, if you did you would realize that quote had very little to do with my points. It was only intended to show that 10x is a general rule of thumb for total flow, nothing more.

What has 10x total flow got to do with 10x sump rates? they ask for 3x sump rates and 10x total flow, not your 10x sump recommendation, trust me I read it properly, I think you were the one that used it to prove your point, but had not read it properly.

Interesting, did you notice that repeatably mentioned the 10x flow is general guideline tank flow but obviously some tanks require more. I just think it's easier to run 10x through the sump and then add extra if it's needed with power heads. I also mentioned time after time that I'm not arguing for 10x sump turnover nor am I recommending it. My point has always been that people have options, and just because some choose to produce there tank flow differently than others doesn't mean they are wrong.

I never took a side and said what was wrong and what was right. Simply put, people think differently and have different priorities, low flow or high flow, it makes little difference.

Unfortunately if you had made this statement 50 posts ago we wouldn't be still posting back and forth, the fact is in general you feel 10x is the acceptable rate and I believe the slower rate to be better and I will explain.

Really? I'm pretty sure I made it clear from the start, even in the thread this discussion started in.....

Are you sure that's what you said? and that you were not biased for 10x sump returns?

10x flow rates through sump..

Due to the large flow rate through the sump to the tank the water flowing through the overflow box creates it's own surface flow towards the overflow box, this is likely the original reason for such high return rates The issue with this method is that when only 2 or 3 x rates are required using 10x or greater pulls more than just the surfactants
from the tank but also a large percentage of non contaminated water which changes the surfactants properties from a concentrated to a diluted solution.

It causes drain issues which if understood could easily be resolved, it enhances micro bubbles in the sump, requires the need for a more expensive pump with high running costs.

Most if not all skimmer manufactures suggest it makes the skimmer less effective.





low flow rates through sump ie from 1x to 3x..

Providing flow is configured correctly the low flow rate will remove surfactants in concentrated form, it will make the skimmer more effective, reduce the need for large overflow systems,reduce the cost of the return pump, reduce the operating costs of the return pump, eliminate micro bubbles, reduce noise and heat.

Really? Are you serious? Most of those are even out of context and in the rest I even stated it's my preference or my belief or my opinion. I'm pretty sure I'm allowed to have a preference and the fact that my preference is around 10x was always made perfectly clear. Yes I provided some reasoning which focused on my preference because others had already covered reasoning for there preferences.

If we can't share our opinions, experience and ideas why are we hear? You actually took the time to search through all my posts and quote only the particular parts (out of context) for the sole purpose to prove me wrong and accuse me of saying something different. I'm sorry but I'm not going to feed your need to debate and argue anymore. Find someone else to stroke your ego.

I read the previous post you are talking about and I didn't see anything that you haven't said in this thread, so I agree we don't need to revisit it.

Everyone uses different terminology. I consider internal skimmers ones within the aquarium, which fell out of fashion 10 years ago. External skimmer is assumed, so I haven't heard the term in a long time. I locate external protein skimmers in sums to catch drips, overflows, and act as a fail-safe.

A 10x flow rate through the sump to be an industry standard or common knowledge. I did a search on Wet Web Media and the first article that came up was this one which recommends a 3-5x throughput. http://www.wetwebmedia.com/circrat.htm

I'm not arguing that a 10x throughput won't work, only that it is inefficient and a poor use of resources. An 800 GPH pump is suitable for a 200 gallon tank as a sump return. I don't agree that it would be a good choice for a 20 gallon tank.

Protein skimmers are limited to removing a maximum of 25% of the TOC so there will always be a buildup of dissolved organics that the protein skimmer cannot process. Your example of the two skimmers doesn't apply to our discussion of how much water to move through the sump. If you believe Escobal's theory that the proteins need a two minute dwell time for optimum bombardment time, then the skimmer with a more concentrated feed and longer dwell time will be more efficient than the second example you offered where less concentrated water is processed quicker. The two schools of thought are filter the water slowly and thoroughly, or quickly and less thoroughly. I agree there is an argument for either method, but the subject at hand is "do you move more water through a sump than the amount the protein skimmer will process?".

The secondary question is do you use a sump design that guarantees the skimmer processes the water only once before returning it to the display tank, or do you allow the skimmer to process the water numerous times while new unprocessed water bypasses it?

A higher volume turnover (10x) will cause the water passing over the overflow to crest higher. You will have around 1/2" of water skimmed from the surface. With half of that flow (5x) you will have 1/4" skimmed from the surface. The extra 1/4" collected with a larger pump will not move the surface water any faster, it will only dilute the surface film collected. Allowing half of that diluted water to bypass the protein skimmer due to an oversized return pump, coupled with a sump design that allows the water to be reprocessed over and over makes the system even less effective.

A horizontal barrier for an overflow is a piece of horizontal acrylic, eggcrate or glass that sits above the overflow edge perpendicular to it. It acts like a long slot rather than a series of small slots. It stops fish and inverts from getting through the same as vertical slots. Nothing gets trapped in the dry part of the overflow. The other way of draining without losing half of your surface area and breaking surface tension with teeth is to have a smooth overflow edge and place gutter guard mesh just inside the overflow box. As there isn't a gap, nothing will get stuck in the overflow and dry out.

There is no head loss with a closed loop even if you locate the pump in a basement because the intake is at the same height as the return. There is some friction loss if you use too many elbows, but Tigerflex hose minimizes it. Powerheads are a poor choice for added flow because they do not have adequately diffused intakes so they can injure livestock. They also cause heat transfer, vibrations, stray current, and poor flow dynamics. An external pump closed loop has a higher upfront cost but lower operational cost and more longevity (10-20 year pump life vs. 4-6 year pump life). The popularity of powerheads stems from low $50 increments needed to implement them. If you are on a budget, they get the job done without major drawbacks, but in the long run the cost more, require more maintenance and are less efficient.

Your current return pump RE65m3 (1717 GPH @ 65 watts) moves approximately 10x the volume of your display tank. If it was replaced with an RE25m3 (660 GPH @ 38 watts) it matches your skimmer pump which I estimate to be about 500GPH, and you would save 27 watts. Prop powerheads are not accurately rated for water movement so the flow rates the manufacturers offer, but let's assume they are accurate for the sake of discussion. You claim you are getting 3000 GPH @ 45 watts from the two powerheads combined. Using your numbers, you could add another powerhead for 22.5 watts and add 1500 GPH flow to make up for the 500 GPH you are dropping by matching the sump turnover rate with the protein skimmer intake. You would have a net gain of 1000 GPH flow with no bypass of the protein skimmer. There are numerous benefits for draining less water mentioned already.

A closed loop system offers the following benefits if executed properly...
1) Hidden influent and effluent lines.
2) Less heat transfer.
3) Less chance of stray electrical charge or shock hazard.
4) Less vibration.
5) No electrical cords in the water or running over the top of the tank.
6) Easy access to intake strainers.
7) More laminar and less turbulent flow for better inertia.
8) The ability to position flow anywhere in the tank.
9) Easy removal of pump if necessary.
10) True flow volume ratings.
11) High pressure flow.
12) Long pump life.
13) Only one cord to plug in.
14) Better circular flow.
15) The ability to locate the pump in a remote location (service area).

I make my technology and methodology decisions based on a thorough thought process, not based on my 30 years of experience in the hobby or 22 years experience in the aquarium industry :) In the 70's & 80's we used a 3x total flow rate for the display tank. In the 90's, a 10x flow rate became commonplace (likely the source of your information), and in recent years 20-40x has become the acceptable range. From my experience quality is better than quantity. If you use powerheads randomly aimed at the rock formation or front glass, you will need 40x flow to get the results you are looking for. If proper flow dynamics are implemented (circular flow, laminar flow, and up-flow for suspension) then you can get by with as low as 15x the volume of the tank for total flow.

The Herby method of draining was common in the 90's. It fell out of fashion after the Stockman and Durso modifications were introduced ten years ago. The problem with the Herbie method is it allows for a small drain point (one you can't even monitor) that can potentially clog. A safer system is a true siphon drain with a Stockman or Durso emergency drain.

I don't think you can fake a car in a car show or a tank in a TOTM. My point was a TOTM is a chance for everyone to see a nice tank that is successful, not a chance to follow the owners learning curve. You will see every possible method with good results. As a result, it's hard to measure their success and decide on the merits of the system. TOTM owners aren't required to explain or defend their methods. It's just raw data with a few anecdotes. I read a lot of books and articles and spend a lot of time on forms. I just don't have time to read a TOTM write up. I skimmed your tank build thread, but I would have read it if I was on this site as it played out. I guess news is more interesting than history to me :)

Europeans don't use T5 because it's better, but because it's cheaper. I lived in Europe for the last year and I can tell you from talking to hobbyists and industry people, MHL is preferred. T5 picked up some interest a few years ago, but they are waning in popularity now. Hydro rates are much higher in Europe, as is fuel. They all drive diesel over there (which I prefer) but they wish they could afford our gas guzzlers.

My clients look for aesthetics (or fluff as you call it), not fancy equipment or rare livestock. There is no point in putting filtration details on my website. I have lots of pictures posted on other forums (RC etc.). I prefer to modify cost effective filtration devices and lighting, rather than throwing money at overpriced equipment and haphazard configuration of it. I don't do maintenance or much in the way of stocking so I don't have many pictures of mature tanks.

You have quoted someone who is saying exactly what I am saying and counters your claim that 10x the volume of the tank needs to go to the sump whether it's needed or not.

"as long as you understand that this does not mean that you need to move 1000 gallons of water in and out of your aquarium" :question:

I simply quoted where you suggested that 10x was the magic number, not one of these quotes was out of context, the very fact that you disagree with me confirms the fact that you subcribe to higher than lower flow.

I will be the first to admit I enjoy playing the devils advocate. A debate or discussion doesn't have to be an argument. As long as you present your position with some substance you can't possibly be wrong, just different. There's also no reason why you have to follow my advice even if it is valid. I've used oversized, less efficient equipment just because it works out that way sometimes.

There are many contradictions in the reef hobby. I've run skimmerless tanks, tanks with no water changes, closed loop (pressurized) filtration systems, and experiments with every method that warranted the effort. Some work better than others, but they all work. I've done more than a few 180's, but I always admit it when I do it. I'm willing to take or at least consider advice from the bottom or top of the hobby.

You have the right to disregard information, but you can't dispute it with hollow claims for 50 posts then try to back peddle that you never said any of it.

I'm sure this thread has been interesting reading and a great soap opera for all that are following. Three people in the aquarium trade having a heated argument about a simple subject. Everyone is going to think it was staged :)

I think this particular horse is sufficiently flogged. If someone wants to discuss the merits of water changes in a new thread, I'm there. I'll even take "against" :)

How about propeller pumps like Ecotech Vortechs or Tunze stream pumps? They address most of the cons of powerheads and consume significantly less power than a closed loop.

I would rather discuss the merits of not having teeth in an overflow box:)

This would make a great discussion.

Teeth not good? All the aquariums you buy with built in overflows that I have seen,have slots.

Yes they do.. why?

Because you imply that teeth are not good.
So I am wondering why are they not?

Teeth reduce the surface area by 50%, so a 12" overflow is really a 6" overflow. As water passes the teeth the surface tension is broken so you don't skim a quick, thin layer from the surface, but rather more water is drawn from below the surface.

Overflows that have a return line or other flow interfere with the surface tension (flow directed near, or away from the overflow) near the overflow cause it to draw water from lower down. You can do a flake food test on some overflows and see water (& flakes) pulled into the overflow box from straight down. Return lines from the sump should be located at the surface at one end with the overflow box in the opposing end or corner (depending on aesthetics). Centre overflow boxes are less efficient and promote dead spots. Water should flow straight across the surface mixing with old water and flow directly into the overflow box taking with it anything on the surface. This system discourages back siphoning with the sump return and provides superior surface swirl and subsequent ripples if you have metal halide lighting.

Tanks typically come with teeth because aquarium manufacturers don't like change. A single slot is cheaper, stronger and easier to build, but tank manufacturers are slow to change. Most of them still use wet/dry filters oversized drains (allowing air and flushing issues) and one pump systems. In the case of a coast to coast style overflow, teeth make even less sense because the water depth at the edge isn't deep enough to attract fish to swim over it.

These pumps do solve most of the issues I mentioned, and they aren't a bad choice. Personally, I don't want to see any pumps or plumbing, but many people are concerned only about function and not about form.

They do use less power than any closed loop pump currently on the market, but the flow rates they have been designated are not the true values of the water they move. They also deliver volume and very little pressure. A pressure rated pump moves X amount of water plus all the other water it picks up and displaces as it travels across the tank. It's kind of a domino effect. If you were to add a dye to the effluent of the Vortech you would see less of it spread across the tank than what you would see with a typical closed loop pump.

Most of the closed loop effluents I use point up from the bottom to keep detritus suspended and to move dead water from lower regions to the air/water interface at the surface for gas exchange (oxygenation). Vortechs are only suitable for end to end flow, and they do it well.

Closed loop pumps draw in as much water as they put out. So do Vortechs, but the water intake doesn't have any impact on flow dynamics and flow is more turbulent (pumping into walls, rocks & opposing flow) than laminar (circular or rolling effect) without losing velocity due to friction or diffusion.

Typical powerhead set-ups direct water at the reef structure. This is not how it works on natural reefs. Water should change direction to offer suspended food from all angles. Good flow creates a snow globe effect. Chaotic flow with poorly placed powerheads drives detritus into reef structures and the sand bed.

A Sequence Dart pump uses 135 watts, and I pay $0.11 per Kw/h in Toronto including all of the extraneous charges. That comes to less than $11 per month if it runs 24hrs a day. If you can find a more efficient pump that truly moves the same amount of water (3600GPH) at half the wattage then you save $5.50 per month. A savings is a savings, but $5.00 isn't enough to tip the scale much.

I don't have much experience with prop powerheads like the Vortech but they look like they will claim the occasional invert or fish. They also require regular cleaning that you don't need with closed loop systems.

I find that drilling out rocks with a diamond bit or covering PVC ports with concrete or epoxy & aragonite makes them invisible in the tank. I'm trying to get away from swiss cheese tanks with multiple holes to keep costs and liability down. As long as you hide the pipes there's nothing wrong with running them over the top of the tank. You trim $1000 off of the cost of a big tank (no tempering or hole charges), production time is cut in half, and you save on bulkhead and valve costs. This brings the cost down to less than a comparable system with powerheads.

Absolutely not true. In fact one of the pumps was recently scruitinized by Dana Riddle and found to move MORE water than the manufacturers claims:
http://www.advancedaquarist.com/2009/10/review


Again, not true. The pickup from my little Vortech MP20 draws detritus up from the bottom of the tank 14" beneath it to keep it suspended in the water column

See above - not true.

Strawman argument. Poorly directed and placed closed loop outlets do likewise. Your argument here is simply a function of poor application and has absolutely nothing to do with the inherent qualities of either a prop pump or closed loop.

And that 100+ watts difference in heat produced is pumped back into the room and eventually requires more hydro consumption in the form of increased work for the chiller, AC, fan to remove to keep temperatures down. Now you've probably doubled your savings to around $120 a year - I'll take that $120 in savings and go buy some pretty new frags.

Just like you have to clean the impeller on a closed loop pump to remove eventual precipitation so too do you clean up the propeller on a prop pump - no difference in maintenance here.

We are not really talking apples to apples here, both vortech and tunze claim flow numbers that becomes converted to gallons per hour of flow.
I would not argue their claims in the slightest, but just for a second could you answer me one simple question, if a vortech or tunze produce 3000- gph of flow , and you throttle back a dart to produce 3000 gph would the result be the same?

Comments like this make me question your design experience, while I wouldn't expect most hobbyists to understand pipe dynamics I would expect an experienced designer to understand some basics regarding flow mechanics in piping systems. Static head is only one part of head loss and even with correct pipe sizes and flexible pipe friction losses are large and plumbing the pump into the basement would add huge losses from friction. You can never completely avoid elbows, tees, unions, and ball valves. These all add significant losses. In addition adding systems to rotate flow will also add significant losses. But your major losses will always come from pipe length and over time your roughness factor increases adding more friction to the system.

On the average return plumbing friction losses will usually add about the same head pressure as the static head. For example, with proper pipe sizing, if you have 4 feet of static head your total head loss will be around 8 feet total. Closed loops always have more plumbing than returns, more outputs and more elbows. In one of my previous setups I used two dart pumps, one on the return the other on a closed loop which used an 4way OM with four outputs. I got more flow through my return than through my closed loop and the maintenance required to keep it working properly and the added complication and noise was enough to prevent me from doing a similar system.

A good power head like a controllable tunze or vortec is a far superior option. They can be controlled by microprocessors and tuned to a frequency that matches your tank dimensions resulting in maximum water movement with minimal power consumption. The flow control is electronic which allows for unlimited possibilities for both flow control and dynamics. To say a closed loop can do this better is just being closed minded. You're comparing a $1000 elaborate closed loop system to a $50 maxijet, try comparing apples to apples. They also produce much less vibration than most external pumps and will always come out on top in efficiency. Heat transfer through a Tunze is minimal wouldn't add sufficient heat to a system to require cooling. Vortecs have there motors external so they would add even less heat to the system.

The only real advantage to a closed loop is that intakes and outputs can sometimes be hidden better, however both Tunze and Vortec offer solutions for this as well. Closed loops can also be a better alternative for extremely large aquariums where you simply can't get power heads large enough but most hobbyists don't have tanks that large.

I've used Tunze power heads in my tanks and others I maintain for well over 5 years and the very few problems I have had where quickly fixed free of charge by the manufacturer despite the fact that the warranty was expired and I had no proof of purchase. I can't say the same for many external pumps I have used which have certainly proved to be less reliable than the power heads I've used. External pumps that use external motors are far from reliable, seals often fail which quickly leads to bearing failure.

Closed loops are usually done as a cheaper alternative to expensive power heads, not the opposite. And the they slowly being phased out as more and more advancements are being made with DC power heads. An external DC pump could make a come back for CLs but so far something reliable and cost effective hasn't been made available to us.

Head Loss Info, FYI

Excel Sheet

http://www.advancedaquarist.com/issu.../featurejp.htm

Tunzes and Vortecs push flow outwards in an expanding direction, this results in a larger area and therefore a lower velocity. Velocity is not that same as flow rate.

Thanks for posting that article, Dana Riddle is an excellent source. It's good to see hard numbers and it's a shame that manufacturers won't spend the resources to achieve this themselves.

As I stated before, Vortechs work around most of the potential problems that arise from powerhead applications. I still argue that they have the following drawbacks...

1) Only suitable to be located at opposing ends of the tank. They cannot be located on the front, or easily on the back, or on the bottom, or within the reef structure, as closed loops can.
2) They are not directional, meaning they are limited to pointing forward (not up or down or at any other angle).
3) They cannot be easily disguised inside or outside of the tank.
4) They require a network of wires running around the outside of the tank.
5) They are slightly louder than a closed loop pump. CL pumps can be remote, while Vortechs must be on the side of the tank.
6) They give off more heat transfer directly to the tank wall (some acrylic tanks have had stress crack issues. According to Riddle, the external temperature is 138F.
7) They cause vibration within the tank which can disturb livestock.
8) Circular or laminar flow is not possible with Vortechs. Water travels in one direction from end to end hitting the opposing wall or opposing flow. I read the velocity numbers, but I don't have pressure pump values to compare them with.
9) I don't know how often Vortechs need to be serviced, but CL pumps have at least 10 years before the volute needs to be looked at. Calcification only occurs on metallic pumps, so magnet coupled pressure pumps don't need to be soaked in acid. Vortechs have not been on the market long enough to establish longevity.
10) There's always a #10. Vortechs are hard to use with tanks that have cabinetry that covers end walls or aquariums fit into walls where access is limited.

The extra 100 watts used by a closed loop pump (if that is truly the case) would not be 100% heat generation, and even if it was, it wouldn't impact the cooling system of a house. These days most people open windows before they turn on the A/C. I'm not about to argue that it contributes to heating your home in winter either :)

In my opinion, the flow from a closed loop pump has more flexibility to be used for better flow dynamics than a Vortech system. By no means does this make a closed loop system a license to use poor flow placement, nor does it exclude Vortechs from fulfilling some of the flow requirements of a tank.

If optimum flow dynamics are in place, which is more readily achievable with a closed loop system, a 15x turnover ratio can be just as effective as a 40x turnover ratio. It is arguable, that 3600 GPH with a closed loop is worth 4800 GPH from a well configured Vortech system.

If you aren't particular about aesthetics or flow dynamics, then Vortechs will work well for you. If you feel you can recoup the initial cost of a series of Vortechs with energy savings, then it has further added value.

That wasn't what I asked, so I will rephrase, if I throttle back a Dart to 3000 gph and make the outputs disperse similar to a tunze or vortech would they be similar?

Yes and no, same flow rate different velocity. The lower velocity and greater spread creates an advantage as simulates natural water movement better.

http://www.jlaquatics.com/images/tunze/6080-main.jpg

I know what you are saying, and totally agree.

3000 gph from a dart will INDUCE a lot more flow then that in the tank. it is hard to compare that with a tunze or similar powerhead.

So we agree that if I could make the outlets of a Dart replicate the Tunze/vortech with the dart throttled to be the same as the flow then we would have identical flow?