Who rates skimmers

[mr.wilson]

Originally Posted by sphelps

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.

I stated there was no head loss, not that there was no friction loss. I was responding to your comment about head loss with closed loop pumps being significant. If you use the RC flow calculator you will see that an elbow, two ball valves and 15' of pipe will drop a Blueline 70 from 1710 GPH to 1620 GPH. This is an example of a closed loop pump located in a basement below the tank, you would have less friction if it were located directly below the tank and of course you could add friction with other plumbing. I simply don't see this as a significant issue, and you never mentioned it in your comparison for likely the same reason.

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.

What are you trying to accomplish with variable speed on the Vortechs or Streams? An intermittent reduction in output only reduces the volume of water you are moving (and electrical consumption). An Oceansmotions 4 Way maintains the same flow rate within the tank while offering a passive surge and allows detritus to momentarily settle for coral feeding, then pick up again before it reaches the substrate. If you time the ports properly, detritus can be passed from one end of the tank to the other using 50% less flow than four static effluents. A powerhead system is limited to side to side flow, and while one side is off, your flow is now at 50% capacity. A closed loop pump with a 4 way is always delivering the right amount of water to right location at all times. You would need twice as many powerheads to make up for the time they are not running for side to side motion.

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.

What are the solutions that they offer. The Dana Riddle article confirmed some of the flow claims so they got some points with me for that, and I would be happy to hear about more hidden benefits.

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.

Shaft driven pumps like Sequence are not suitable for marine aquariums so I'm not surprised you had problems, but that is like me directly comparing a maxijet to a Vortech, which I have not. The main problem hobbyists experience with external pumps is sumps running dry (which would also happen with a submersible pump), and saltwater dripping on the motor (which is negligence). To a lesser extent sand in the impeller or dust in the fan also occur, but once again these same people would be negligent with powerheads. I have experienced a 1% return or repair issue with external pumps, and although I don't use powerheads, I always see a mountain of them at local aquarium stores return bins and replacement parts are well stocked, while replacement parts for external pumps is a non-issue.

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.

Sequence makes a DC Dart. The only application I could see is a series of deep charge marine batteries for a backup system but personally I prefer air lifts.

Head Loss Info, FYI

Excel Sheet

http://www.advancedaquarist.com/issu.../featurejp.htm[/quote]

[mr.wilson]

Originally Posted by sphelps

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.

It also results in detritus being pushed down into the substrate rather than up to the surface for suspension, surface skimming and gas exchange.

If you like the outward flow of a Vortech, it can be easily replicated on a closed loop with a penductor, or a series of them if you split your closed loop into several ports.

[sphelps]

Vortecs have the advantage of the external motor which of course presents limitations however hobbyists have the choice to use them when appropriate and could also use Tunzes which solve many of these limitations.

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.

They can be located virtually anywhere, including within the reef structure. Maybe not as desirable in some locations but they also have the advantage of relocation if aquascaping or flow demands change, not as easy with closed loops. These pumps also have the advantage to pulse at critical frequencies to produce a natural wave type movement. Corals do not benefit from direct flow so I don't even see the advantage of pointing flow directly at the reef structure.

2) They are not directional, meaning they are limited to pointing forward (not up or down or at any other angle).

Tunzes are certainly directional, the new models have movement in almost all directions.
"they offer a lot of flexibility with respect to positioning and orientation of the water stream, which can be adjusted in such a way that an effective flow is produced over a long distance in the aquarium at lower power consumption."

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.

Cables can be tied back to one location like the back of the tank, or if all sides are viewable through the overflow.

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.

The further remote the more friction loss and most don't like to run large PVC pipe through their house. Vortecs are virtually silent if balanced correctly, and you can't even hear a Tunze running. CL pumps like a Dart are very noisy in comparison.

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.

Splitting hairs, heat will transfer from the motor to the water moving through an external pump in a similar fashion. The housings on the dart pumps I owned were warm to the touch and I've seen similar pumps fail when flow valves were shut and forgotten about. The pump is air cooled but still relies on the flowing water to remove part of the heat produced.

7) They cause vibration within the tank which can disturb livestock.

Interesting theory but I asked my fish this morning, they don't mind it. Pumps can also be turned down over night with controllers and create a more calming environment.

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.

Turbulent flow could be a good thing as it would create a more random flow pattern adding to the snow globe effect. However you may have it backwards, a Tunze or Vortec spreads flow out over a larger area creating lower velocity which would promote a more laminar environment, closed loops often use jets which create high velocity patterns which disturb the water around it creating a turbulent boundary layer.

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.

Completely false, external pumps, shaft driven, or magnetically driven, require frequent maintenance. Magnetically driven pumps require impeller and shaft cleaning as often as any power head. Shaft driven pumps also require frequent cleaning to prevent seal failure and build up which creates both resistance and noise. When I had issues with my reeflo dart the manufacturer stated the the impeller housing must be flushed and cleaned every three months to prevent seal failure. The seal also should be constantly checked for salt creep for the same reason.

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.

So a closed loop is easy to access with limited cabinetry access? I can't see how in most aquariums a closed loop offers easier access than power heads like tunze and vortec.


In my mind quality power heads like Tunze and Vortec offer the following advantages over CLs.

1) Easier setup and maintenance
2) Better resale and easier to incorporate in new tanks. Plumbing for a closed loop is expensive, I did a 4W OM on a clients tank and it cost around $400, very rarely can plumbing parts transfer to a new tank.
3) Can be relocated at anytime with minimal effort
4) Can be upgraded or down graded without major modifications to the tank
5) Use less power, greater efficiency a dart runs 22.5 GPH/W while a Tunze Stream 6000 runs 123.2 GPH/W
6) Create less noise, sorry but a tunze is quieter than a dart
7) Much better flow control and have better capability to produce more natural wave flow. The vast selection of electronic controllers is far superior to the OM and SCWD devices which are only ones I'm aware of.
8) Simplicity, closed loop systems require more experience in plumbing. You also can't really contain both a closed loop system and a sump system in one stand, it would have to oversized or very tight making maintenance a nightmare.
9) No tank modifications needed, Closed loops require a swiss cheese tank to hide the plumbing
10) Better reliability all the way round. The external plumbing required for a closed loop can be a dangerous game, bulkheads can leak down the road and replacement would be a tremendous headache requiring the complete dismantle of an established aquarium. People worry enough about the actual tank seams leaking, why add more potential for leaks?

I could go on but 10 seems to be the magic number.

[sphelps]

Originally Posted by mr.wilson

I stated there was no head loss, not that there was no friction loss. I was responding to your comment about head loss with closed loop pumps being significant. If you use the RC flow calculator you will see that an elbow, two ball valves and 15' of pipe will drop a Blueline 70 from 1710 GPH to 1620 GPH. This is an example of a closed loop pump located in a basement below the tank, you would have less friction if it were located directly below the tank and of course you could add friction with other plumbing. I simply don't see this as a significant issue, and you never mentioned it in your comparison for likely the same reason.

Yes very good but that's over 8 feet of head pressure, it's significant but its a pressure rated pump so flow losses are minimal with added pressure. How much power is that using? Around 300W, ouch! not something I would want to run. And exactly who can plumb a closed loop with such little fittings? Take the same case but more realistic and add 3 more elbows, 4 more ball valves, 6 unions, over 4 exists and you'll see that jump up to 13 feet. Then compare that to a more common pump like a dart and you'll get just over 10 feet which drops the flow from 3600 to 1200. You did state that friction exists but it was small, this simply isn't true and there would be a huge difference in plumbing to the basement, add 20 more feet of pipe and pressure jumps to 16.5 feet on the blueline. And none of that even considers what that OM does for head loss, I wouldn't even want to know.

What are you trying to accomplish with variable speed on the Vortechs or Streams? An intermittent reduction in output only reduces the volume of water you are moving (and electrical consumption). An Oceansmotions 4 Way maintains the same flow rate within the tank while offering a passive surge and allows detritus to momentarily settle for coral feeding, then pick up again before it reaches the substrate. If you time the ports properly, detritus can be passed from one end of the tank to the other using 50% less flow than four static effluents. A powerhead system is limited to side to side flow, and while one side is off, your flow is now at 50% capacity. A closed loop pump with a 4 way is always delivering the right amount of water to right location at all times. You would need twice as many powerheads to make up for the time they are not running for side to side motion.

You're obviously not too familiar with what my profilux controller can do with my Tunzes, way beyond side to side movement and simple pulses. From sine waves to right angle shorts and random % additions plus storm simulations natural wave movements and night modes I'm sorry but it does way more good than a OM. You could do the exact same as an OM with such power heads at that would be the simplest program, but nobody would because the other options are better.

What are the solutions that they offer. The Dana Riddle article confirmed some of the flow claims so they got some points with me for that, and I would be happy to hear about more hidden benefits.

Check out that nice picture I already posted, rock covers can hide such power heads just like a closed loop.

Shaft driven pumps like Sequence are not suitable for marine aquariums so I'm not surprised you had problems, but that is like me directly comparing a maxijet to a Vortech, which I have not. The main problem hobbyists experience with external pumps is sumps running dry (which would also happen with a submersible pump), and saltwater dripping on the motor (which is negligence). To a lesser extent sand in the impeller or dust in the fan also occur, but once again these same people would be negligent with powerheads. I have experienced a 1% return or repair issue with external pumps, and although I don't use powerheads, I always see a mountain of them at local aquarium stores return bins and replacement parts are well stocked, while replacement parts for external pumps is a non-issue.

All the external pumps who have recommended are shaft drive, aren't they? I used darts as an example because you mentioned them in a previous post.

Sequence makes a DC Dart. The only application I could see is a series of deep charge marine batteries for a backup system but personally I prefer air lifts.

Good stuff, so no comebacks for CLs

[mr.wilson]

I was responding to the comments that Canadian had made about Vortechs. Vortechs are easily the best powerhead on the market, if you can still call them a powerhead, more of a magnet spinner. They address most of the problems that submersible pumps cause. If I was talking about Tunze pumps I would have address different issues.

The only reference I have of sound was from the Dana Riddle article where he claimed they have a whine which increase in frequency as they power up and down. I've seen them is use on tanks, but only in fish rooms or noisy hobbyist tanks.

Tunze powerheads can be located anywhere, but they need to be removed for periodic servicing and they have moving parts in the reef. I don't agree that magnet coupled chemical pumps with sealed bearings such as Iwaki require preventative maintenance or volute cleaning. It appears that you experience is limited to non-chemical pool pumps like the Sequence line, so I understand why you don't like closed loop systems. This line of thought is equally as unfair as me comparing a Vertech pump to a maxijet, which I have not done.

I'll admit some of the issues I have listed are not significant drawbacks, like extra power cords, but it was a simple comparison of pros and cons just as I would accept that Dart pump is too loud for a home aquarium and it isn't suitable for marine applications.

I agree heat transfer comparisons are splitting hairs. I was just using Dana Riddles comments about heat in comparison to Canadian's claims of added air conditioning costs to counter the heat thrown from a closed loop pump. They both have external temperatures of 130F, it's just closed loop pumps use heat sinks and fans to mask the heat. You could easily put a fan on a Vortech if it was ever an issue, and I doubt it would.

I don't have the time or desire to look up articles about vibration or moving parts in reef aquariums. They may or may not affect the physiology of fish and invertebrates, but it remains as something to consider when weighing options. Your claim that you can tell it doesn't effect your fish is silly.

Turbulent flow doers not create random flow patterns. They may be more intricate, but they are not random unless you have programmed sporadic sequences into your powerhead controller.

You have to make up your mind about the flow you are endorsing. One minute you are talking about prop powerheads offering lower velocity and fanned out, diffused flow as being beneficial, and in the next paragraph you are saying a closed loop pump has too much velocity so it moves too much water as it passes through the tank. If it moves more water than the amount measured leaving the effluent port, then let's add that to the total flow rate as we should.

My point about pump access with a closed loop was you unplug the pump and shut off two union valves and you can remove it to service, upsize or downsize. With Powerheads you may have to move corals if you have them within the rock work. Vortechs are easy to access because they don't work in these locations and don't utilize suction cups or plastic clips.

In my mind quality power heads like Tunze and Vortec offer the following advantages over CLs.

1) Easier setup and maintenance

Easier set-up, harder maintenance. Closed loop owners forget they are even there, while powerheads are part of routine servicing.

2) Better resale and easier to incorporate in new tanks. Plumbing for a closed loop is expensive, I did a 4W OM on a clients tank and it cost around $400, very rarely can plumbing parts transfer to a new tank.

I don't know which would have a better residual value, but it's a strange benefit to consider. For that reason, I'll give you the point.

3) Can be relocated at anytime with minimal effort

Absolutely, but you will never get it where it works best.

4) Can be upgraded or down graded without major modifications to the tank

Just as a closed loop pump can. A 1" in and out port will fit hundreds of pump possibilities. Once again, planning for re-engineering is a poor selling point.

5) Use less power, greater efficiency a dart runs 22.5 GPH/W while a Tunze Stream 6000 runs 123.2 GPH/W

This is only true if you are measuring strictly the water exiting the effluent port and not the overall effect. The trade off with high volume low energy consumption pumps is velocity. There are arguments for both high and low velocity systems. Closed loop systems can simultaneously offer both with a wave making device, while powerheads are limited to low velocity, lower velocity, and no velocity. Energy savings are nominal. While they may be 50% in the best of scenarios, the hard number is $5-10 a month. In a society where we drive cars that get 20MPG while 60MPG cars are readily available, it's a hard sale. How often do you fill up your BMW gas tank? Whatever you are spending, it's three times higher than what it could be.

6) Create less noise, sorry but a tunze is quieter than a dart

Once again if you are going to compare to a Dart then I will use an oil cooled cast iron sump pump as a basis for powerhead comparisons An Iwaki or Panworld 70 located in a remote location away from the cabinet will not be audible at all. Alternatively a Red Dragon, Deltec or Poseidon pump is also inaudible.

7) Much better flow control and have better capability to produce more natural wave flow. The vast selection of electronic controllers is far superior to the OM and SCWD devices which are only ones I'm aware of.

Then you have proven once again that your knowledge is limited.

8) Simplicity, closed loop systems require more experience in plumbing.

Absolutely, just as proper Tunze Stream placement requires more experience than putting them in the corner where they look good.

9) No tank modifications needed, Closed loops require a swiss cheese tank to hide the plumbing

There is no reason why a closed loop system with an external pump requires and holes in the tank. If you can live with powerheads in the tank and hanging off of the side, then a few pipes running over the trim at the back should not be a problem.

10) Better reliability all the way round. The external plumbing required for a closed loop can be a dangerous game, bulkheads can leak down the road and replacement would be a tremendous headache requiring the complete dismantle of an established aquarium. People worry enough about the actual tank seams leaking, why add more potential for leaks?

First of all, I was right, there is always a #10. You are absolutely correct, a tank full of extra valves, fittings and bulkheads is a liability, especially if it is not done properly. It's a very small liability, but it still exists. A closed loop system with external plumbing running over the trim saves the cost of extra holes, bulkheads and valves. I see a need for only two drain holes with anything else being a luxury. Doesn't your tank have four holes in the bottom? This adds the extra cost of tempering and or a thicker bottom panel. The bottom is the easiest panel to get a leak with as there is more hydrostatic pressure on it and long pipes can bend and cause water to leak past the bulkhead flange.

I could go on but 10 seems to be the magic number.

At least we agree on something

[mr.wilson]

Originally Posted by sphelps

Yes very good but that's over 8 feet of head pressure, it's significant but its a pressure rated pump so flow losses are minimal with added pressure. How much power is that using? Around 300W, ouch! not something I would want to run. And exactly who can plumb a closed loop with such little fittings? Take the same case but more realistic and add 3 more elbows, 4 more ball valves, 6 unions, over 4 exists and you'll see that jump up to 13 feet. Then compare that to a more common pump like a dart and you'll get just over 10 feet which drops the flow from 3600 to 1200. You did state that friction exists but it was small, this simply isn't true and there would be a huge difference in plumbing to the basement, add 20 more feet of pipe and pressure jumps to 16.5 feet on the blueline. And none of that even considers what that OM does for head loss, I wouldn't even want to know.

This is why your use of a Dart was foolish, but you know that now. The total flow loss with a pressure pump is far less than a Red Dragon return pump with only 5' of head.

You're obviously not too familiar with what my profilux controller can do with my Tunzes, way beyond side to side movement and simple pulses. From sine waves to right angle shorts and random % additions plus storm simulations natural wave movements and night modes I'm sorry but it does way more good than a OM. You could do the exact same as an OM with such power heads at that would be the simplest program, but nobody would because the other options are better.

You need to stop comparing my Vortech comments to your Tunze pumps. I know you have more options than a Vortech with regard to positioning but you are still limited, and as such you cannot do what a closed loop can. If I were to choose an alternative method, I would go with the Vortech, not the Tunze. Yes I am familiar with the Profilux controller coupled with the Tunze pumps. I service two tanks that have that combination.

Check out that nice picture I already posted, rock covers can hide such power heads just like a closed loop.

Yes, but they are transient. You still have an electrical cord in salt water and moving parts in your reef. Once you put that faux rock on the powerhead you are losing whatever intake flow dynamics you were hoping for with your Tunze.

All the external pumps who have recommended are shaft drive, aren't they? I used darts as an example because you mentioned them in a previous post.

I think you have me confused with the other guy. If I mentioned Sequence pumps it was only because they are commonly used in the hobby, just as I would refer to a maxijet or Magdrive pump even though I don't use them.

Vortech has taken powerheads to a new level. It isn't a new idea by any means. Aquarium pump manufacturers should be ashamed that it took so long to adapt a simple magnet spinner to the tank. They have been around for over 50 years in the scientific community and they were used in Dynaflow filters in the 70's and Marineland filters in the 80's.

It's too bad there have been no major advances in pressure rated chemical pumps in the past 30 years.

[sphelps]

Well we could go on forever, I still obviously don't agree with all your points and you obviously don't agree on mine. We can always find something pick at and spin against one another so before this gets out of hand again I'm agreeing that closed loops are a good option if done correctly and the space is available. However I personally prefer the use of certain power heads for the reasons stated and not because of my lack of experience or knowledge of closed loops.

I would have been better to have this discussion with a broader audience, I find threads like this quickly die on this site and you end up in this exact position

Not that this would particularly prove anything but I think it would be interesting to setup a poll or two to see what other hobbyists find and believe works before for water flow.

[mr.wilson]

I find that these threads get a good audience. There are over 1200 views thus far, which isn't bad for a new thread with no answers, pictures or swearing.

I fully agree that powerheads are a sound choice for some people. It was never a matter of one being wrong and one being right, but one of which one is right for whom.

Unfortunately we don't have much science to help the situation. We have a Dana Riddle article that gives ratings for Vortech pumps but without flow ratings for external closed loop pumps we are still comparing apples to oranges.

I'm sure a poll would determine that powerheads are more popular, but as you mentioned it doesn't prove anything. I guess I have to go back to work then

[sphelps]

Yes lots of viewers but few writers. What I meant to say was these threads often die because it comes down to a couple people saying the same thing over and over again and it would be better if more people would pipe in with their opinions and experience. Group thinking and discussions are always better in my mind and the more people in the group the better. It's like classic statistics, if you have a jar of gum balls and have to guess how many is in the jar stats proves that the average number of a large group of people will be always be closer than one individual guess. Of course luck isn't considered in stats

[mr.wilson]

Okay. I guess 710 gumballs.