Who rates skimmers

[sphelps]

Originally Posted by mr.wilson

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.

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

[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]

[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]

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.