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Old 04-03-2010, 11:15 AM
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Originally Posted by Mr OM View Post
That is the whole point Mike.

Firstly we all have overflow commonly called prefilter boxes...Why call them this?

Because they are moving the surface water only from the tank when done properly, If you imagined that fish waste, coral waste and detritus was similar to oil it isn't hard to visualize oil floating on the surface of the DT, the prefilter box is there to remove it, the slower the removal the more concentrated that would be , if the extraction rate is increased the oil is mixed with more water and becomes diluted.
So this oil/ water mix then goes to the sump where some use filter sock for containing large bits etc, it then should enter the skimmer as concentrated as possible and then the skimmer can do it's job properly.

Why anyone would want to keep returning dirty water continuously back to the tank so they can keep skimming a little at a time is beyond me, get it out get rid of it and return clean water back to the tank.
Agreed.

Slowly we can see the use of closed loops falling out of favour because of the high energy costs and a number of other reasons (tank wall integrity, OMs, maintenance, etc). That leaves powerheads and propeller pumps. Many people, a long time ago, decided they preferred to not have PHs in their tanks long term, if not for the appearance, then for safety. That leaves propeller pumps which are very costly once you get beyond, well, one. For this reason I think we will see large volume returns continue.

I don't use a pre-filter so I have nothing to add about that. I do use filter socks but that's just to reduce bubbles in the sump.
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Old 04-03-2010, 11:43 AM
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I'm gonna use the same car analogy. Going too slow means you are burning all the fuel that goes into the engine but you are not utilizing all the energy that the car is capable of, going too fast and you are not burning all the fuel that goes into the engine. In either case you need more fuel to get to where you want to go. The sweet number according to experts if I am not mistaken which they say would be fuel efficient would be between 60-80.
In a way if you have a tank that is 100 gal and you have a skimmer that has a pump rated at 800 gph and you have a turnover rate of 1 that would just mean that at least the same water goes through the skimmer 8 times. If you have a turnover rate of say 40 that would mean water would just be passing from your tank to your sump without even going to your skimmer. It you go around say 4-8 then the water would at least pass through your skimmer at least once or twice. I think that would be efficient enough. Going too slow and you are just going through water that has already been stripped of all those waste and oil and going too fast and you are not getting stripped at all.
Same thing with the heater if you have it in your sump. If it is too slow then the water is not heated up with evenly, if it is too fast then the water just passes through it without getting heated up at all.
best way is to just match the capability of your equipment with the turnover rate of your tank to your sump otherwise you are either wasting energy either it is just being redundant or not doing the job at all. It is going to be a trial end error thing but you will get the feel for it as it goes along.

Last edited by Bloodasp; 04-03-2010 at 11:55 AM.
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Old 04-03-2010, 11:59 AM
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I'm gonna use the same car analogy. Going too slow means you are burning all the fuel that goes into the engine but you are not utilizing all the energy that the car is capable of, going too fast and you are not burning all the fuel that goes into the engine. In either case you need more fuel to get to where you want to go. The sweet number according to experts if I am not mistaken which they say would be fuel efficient would be between 60-80.
In a way if you have a tank that is 100 gal and you have a skimmer that has a pump rated at 800 gph and you have a turnover rate of 1 that would just mean that at least the same water goes through the skimmer 8 times. If you have a turnover rate of say 40 that would mean water would just be passing from your tank to your sump without even going to your skimmer. It you go around say 4-8 then the water would at least pass through your skimmer at least once or twice. I think that would be efficient enough. Going too slow and you are just going through water that has already been stripped of all those waste and oil and going too fast and you are not getting stripped at all.
Except that the sump isn't a separate unit; the tank and sump are the same system. The turnover rate should be a non-issue. What is important is that the overflow box is large enough to handle the volume going through it. If your OF is 10' long and is able to extract the surface of the water and not just a lot of water, it is running efficiently. This means you could have 1000x turnover in your 20 gallon tank. The amount skimmed off the surface, whether 10% or 100%, removed by the skimmer is a non-issue because the skimmer can only handle what it's rated for.

I think the issue here is redundant recycling of clean water, not turn over.

This whole argument is theoretical.
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Old 04-03-2010, 12:05 PM
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Am I going off topic here? The poster was asking how fast the turnover rate is suggested. And so is the analogy I was putting in there. A car is not separate from it's engine either. It may not be separate from your system but it contains a lot of your equipment. It may or may not be that the skimmer might be efficient with a slower turnover or not, believe what you want until a thorough study comes out about it. The skimmer isn't the only equipment in your sump some of them do need some lingering time to work efficiently at the same time they won't work well if the water was almost not moving.

Last edited by Bloodasp; 04-03-2010 at 12:38 PM.
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Old 04-03-2010, 12:45 PM
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The opening post asked about sump turnover,not tank turnover. whether you like it or not if you have an overflow box you do have a prefilter box they are technically doing the same thing, why are people saying as I said years ago that having no teeth in the oveflow box is more effective? why because it skims better.
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Old 04-03-2010, 03:24 PM
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There might be an ideal turnover rate if the skimmers were 100% efficient but doubt they're close. Even if they were, what's the big deal if one decides to have the return pump contribute to the overall turnover of the tank. Really, if one could accurately measure waste remove by our little hobby skimmers, would there be a significant difference between 1x, 2x, 5x flow through?
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Old 04-03-2010, 03:27 PM
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Ok this is totaly silly, a 1X turn over for tank volume will have absolutly nothing to do with skimmer preformance. you telling me if I have a 180 gal tank with a 1X turn over a berlin will do a 100% skim on it..

you not going to get a 100% skim unless you match the flow of the sump to the flow of the skimmer, that means your overflows go into your skimmer then to the sump and there is no way you could aford a skimme that will handle that flow.

so in the real world, shoot for between 3 to 10X turnover depending on what the sump can handle. this is the most important thing as depending on how you designed the sump will dictate the max amount of flow that is reasonable throug it. personaly I go for 10 to 20X through the sump as I have it set up like a setteling pond. with 160X turn over in a main tank not much settles out of the water colume so I take it to the sump where it goes high speed through a couple baffeles then just opens up to a very large area where it slows down and junk falls out. so that was about 1800 gal per hour through the sump, my skimmer was a becket fed by a mak4 so irt was probably doing about 800gph.

this 100% vs 10% thing is a waist of a good argument also as no one is going to do a 100% waterchang every month and it just doesn't matter after the say 10 hours of doing 80% and 10% you are gettting the same results from either method and no skimmer has a 100% efficiency, maybe 20% if you are lucky.

so don't worry about skimmer preformance vs sump flow. set it up so the flow is good and not to turbulant in the sump, get the best skimmer you can afford and enjoy the tank.

Steve
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Old 04-03-2010, 03:29 PM
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Quote:
Originally Posted by Mr OM View Post
The opening post asked about sump turnover,not tank turnover. whether you like it or not if you have an overflow box you do have a prefilter box they are technically doing the same thing, why are people saying as I said years ago that having no teeth in the oveflow box is more effective? why because it skims better.
no teath yes will take the surface water a bit better, not a lot, but the big advantage is it is quiet and less air in the overflow so you get better flow.

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Old 04-03-2010, 04:23 PM
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For what it's worth, the proper flow rate according to Pedro Ramon Escobal, the man who literally wrote the book on filtration devices http://www.amazon.co.uk/Aquatic-Syst.../dp/1888381051
... and wrote the book on rocket science. http://www.amazon.co.uk/Methods-Astr...tt_at_ep_dpt_1
... then another book after the rocket scientists finally understood the first one. http://www.amazon.co.uk/Methods-Orbi...tt_at_ep_dpt_2

According to Escobal, founder of Aquatronics (premier aquarium medication manufacturer) and Filtronics (innovative filtration device manufacturer), protein skimmers should have a 1.333333 throughput per hour for maximum efficiency. He uses the same flow through rate for sumps for obvious reasons. If you go on to read his recommendations for UV sterilizer throughput the math works out to 2 x per day, yes DAY turnover ratio.

Media filters such as fluidized beds operate with small powerheads so we're talking 300 GPH, at best. Refugia require slow flow for pod development and longer dwell time with algae.

As far as filter socks go, they work best with a slow flow so the detritus you collect isn't pulverized by water flow and converted from POC (particulate organic carbon) to a liquid form - DOC (dissolved organic carbon). keeping the detritus in the display tank suspended with dedicated water flow such as a closed loop or powerheads is the key to collecting more detritus. A flow rate of 1.33333 x the volume of the display tank is enough to collect the maximum amount of detritus without diminished returns.

Ozone is dosed into the protein skimmer so we can go with the magic skimmer number of 1.33333. Are you starting to see a pattern yet? All of these devices are operating concurrently, that is to say the water entering one, then goes into the next device until the water exits the sump.

There is absolutely no reason to deliver more water to filtration devices than they require to operate. It is a waste or resources and actually decreases performance. It skims a thicker water sample from the surface of the display which yields less surfactant proteins, pre-skimmed for the protein skimmer. The water travelling over the overflow box does not move faster (meaning more rapid surface skimming) when you increase the return pump output volume. The water simply climbs higher over the box drawing the excess water from below the surface "skin". This taxes your overflow drains causing more microbubbles, noise, turbulence, saltcreep and heat & energy from the pump.

The most efficient filtration system is a first in first out (FIFO) system. The water skimmed by the overflow box should be fed directly into the protein skimmer in the sump. That water should then be drained out of the skimmer and move on to the other devices you have selected in series/succession (one at a time). If your protein skimmer does not allow for direct feeding, you should locate the protein skimmer in a partitioned area at the beginning of the sump where water drains from the display tank at the same rate as the skimmer pump (likely 1.33333 x display tank volume per hr). The processed water that exits the protein skimmer should be directed over the partition so it enters the next stage of filtration, usually the refugium with media filters being last.

If you implement this simple system, you will process 100% of the water entering the sump, and do so only once. If you do not use a FIFO system your protein skimmer is filtering the same water over and over randomly, missing some display tank water entirely.

Now let's look at some scenarios if the return pump and skimmer pump are not matched exactly. If the skimmer pump is stronger than the return pump, more water will go through the skimmer than the amount entering the sump. This will result in the excess portion of water travelling "backwards" over the partition from the second stage back to the first to equal out the pumps. The disadvantage of this is that excess water will get processed a second time, but no water will go unskimmed. If the return pump is stronger than the skimmer pump, the excess flow will bypass the skimmer, but you will not process any water two times before it is returned to the display tank. If this is the case, it is a lot easier to restrict the return pump than mess with the skimmer pump. Some manufacturers allow you to adjust air flow which in turn lowers or increases water flow.

If we continue with this idea, the media filters could be housed in the second partition with a dedicated pump (powerhead). The effluent (exit/processed) water from the media filters would be directed over a second partition so it is processed only once. If you use a return pump bypass, the water will be reprocessed randomly.

In summary, the sump is not a filter, it's merely a vessel to old them. If we could live with the clutter hanging on the back of the display tank, we would not have to go though the expense, noise, flood hazard and bubbles that come with moving water to and from a sump. You don't have to be a rocket scientist to understand that less is more in the case of display tank flow through/throughput rates, but if you ask a rocket scientist he will agree that the flow rate is governed by the protein skimmer pump output which happens to be in the neighbourhood of 1.33333 x the volume of the tank.
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Old 04-04-2010, 02:36 PM
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Quote:
Originally Posted by mr.wilson View Post
For what it's worth, the proper flow rate according to Pedro Ramon Escobal, the man who literally wrote the book on filtration devices http://www.amazon.co.uk/Aquatic-Syst.../dp/1888381051
... and wrote the book on rocket science. http://www.amazon.co.uk/Methods-Astr...tt_at_ep_dpt_1
... then another book after the rocket scientists finally understood the first one. http://www.amazon.co.uk/Methods-Orbi...tt_at_ep_dpt_2

give me a break, there are tones of books out there that say you want over 20X flow rate. just because some one writs a book doesn't mean it is right, it may work for him, it ma be how he feels, but that is it. as for being a rocket scientest whopity doo.. I am an Marine Engineer, he my direct line of work deals with water flow and movment, but does it mean I know about turf scrubbers... hell no never even seen one, but I di know alot of people have to low of flow on them also (I have been reading about them) but I do know water flow and pumps, and heaters, and well anything else that is mechanical with out tanks. hmm maybe I should write a book now that I am retired.

Steve
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