Two or more closed loops - counterproductive?

[dkeller_nc]

don't forget to use unions at the inlet and outlet sides of the pump so you can disconnect the pump in the future if it fails or for cleaning!

Yeah, I second this. I've personally made this mistake, though on an Iwaki return pump setup rather than a closed loop. My error required plumbing my reef with flex tubing and a submersible pump while I spent a Saturday crawling under my 90 gallon reef to saw apart the PVC, reconfigure it with true unions, and wait for the PVC glue to completely cure. Not fun.

By the way - perhaps the best way to do this on a closed loop given the inherent space restrictions is to use "true unions" that are ball valves and unions all in one piece. BRS sells them, as well as professional plumbing stores.

 

[acesq]

pump

pump

I've got my design figured out for my peninsula build:

I'll have an external oveflow on the wall end and 2 DC closed loop pumps. Each pumps will draw from a separate 2" bulkhead on that same panel. One pump will have 4 - 6 1" or 3/4" outlets drilled into the bottom panel (I will be cavitation conscious but believe I will have sufficient head pressure on the intake side to overcome it) all pointing toward the wall opposite the overflow panel and angled toward the surface. (Padrino's build has this and it was very well thought out). The second pump will discharge from above the panel opposite the overflow through a 1.5" Mocean oscillating return a few inches below water level pointing back toward the overflow. Both pumps will be controlled to produce a pulsing effect. Hopefully this arrangement will generate a decent grye effect picking up the detritus and sending it across to the overflow. What do you think?

The next step is finding high flow DC pumps. I want at least 3000 gallons per hour. The 12000 lph waveline and DSS pumps look to be another few months away from release, I can't find a source for the Blue-eco pond pumps that a few here are using successfully and I don't want to (but wish I could) spend $2k on an Abyzz. Any ideas?

 

[Gandolfe]

I installed a shut off valve between the union and the tank on both my closed loops so I could shut the flow of water to the pumps and minimalize water when disconnecting pumps for maintenance or whatever. closer valve is to union less water when you disconnect at union. if you want to get really fancy they make y's and you can install it between the pump and the union with a valve to drain system there if you like! but you'd be using 4 valves instead of two, but will make it easy to drain water out before disconnecting pumps. All depends on how much space you have and how much $$$ you want to spend to make it easier

 

[dkeller_nc]

(I will be cavitation conscious but believe I will have sufficient head pressure on the intake side to overcome it).

While the absolute pressure (i.e., how "deep" the pump is operating at) does affect cavitation, putting head pressure on the intake side doesn't usually solve a cavitation problem - you have to put back pressure on the outlet side. Presuming that you're going to install a true union ball valve on the pump discharge side so that you can take apart the system for cleaning, if you encounter cavitation all you have to do is valve down the outlet a bit.

The next step is finding high flow DC pumps. I want at least 3000 gallons per hour. The 12000 lph waveline and DSS pumps look to be another few months away from release, I can't find a source for the Blue-eco pond pumps that a few here are using successfully and I don't want to (but wish I could) spend $2k on an Abyzz. Any ideas?

One possible solution would be to use AC motor pumps on a VFD. Variable frequency drives used to be harshly expensive and were only available for 3-phase motors. But advances in IGBTs (insulated gate bipolar transistor - a type of power transistor) have made them much cheaper, to the point where they are at least in reach for a hobbyist.

The link is too long to post here (RC's software will truncate it), but google wolfautomation hitachi compact micro AC drive. The price for a 1/2 horsepower single-phase VFD is $135.

Many of these VFDs are externally controllable - you use a 0-10V signal to set the speed on the VFD, so you can have something like an Apex provide you with surge flow.

 

[acesq]

While the absolute pressure (i.e., how "deep" the pump is operating at) does affect cavitation, putting head pressure on the intake side doesn't usually solve a cavitation problem - you have to put back pressure on the outlet side. Presuming that you're going to install a true union ball valve on the pump discharge side so that you can take apart the system for cleaning, if you encounter cavitation all you have to do is valve down the outlet a bit.

One possible solution would be to use AC motor pumps on a VFD. Variable frequency drives used to be harshly expensive and were only available for 3-phase motors. But advances in IGBTs (insulated gate bipolar transistor - a type of power transistor) have made them much cheaper, to the point where they are at least in reach for a hobbyist.

The link is too long to post here (RC's software will truncate it), but google wolfautomation hitachi compact micro AC drive. The price for a 1/2 horsepower single-phase VFD is $135.

Many of these VFDs are externally controllable - you use a 0-10V signal to set the speed on the VFD, so you can have something like an Apex provide you with surge flow.

Correct, I'll have a true union ball valve between the pump and each outlet.

That VFD look great. However, I'm still going to try to find a suitable DC pump in order to keep the noise to a minimum. If I can't find one, I'll consider one of the larger RD pumps which are fairly quiet and try to hook up one of those controllable VFDs.

 

[dkeller_nc]

Technically, a DC pump doesn't make any less noise than an AC pump. The noise level typically comes from the motor, and the larger pumps generally have TEFC motors (Totally Enclosed Fan Cooled). The fans on these motors are generally what generates the noise, assuming the pump is a magnetically driven one. Non magnetically driven pumps tend to be quite noisy because of the shaft seal.

 

[acesq]

Technically, a DC pump doesn't make any less noise than an AC pump. The noise level typically comes from the motor, and the larger pumps generally have TEFC motors (Totally Enclosed Fan Cooled). The fans on these motors are generally what generates the noise, assuming the pump is a magnetically driven one. Non magnetically driven pumps tend to be quite noisy because of the shaft seal.

True enough, but the quality of the manufacture seems to have alot to do with noise. I wish the manufacturers for the aquarium industry would publish noise levels along with the other performance data -- we're putting these things in our living rooms! Have they not considered the spouse factor?

 

[ca1ore]

For a set-up that will be this $$$ heavy on the equipment investment side, you might consider using the FlowWolf digital flow diverter from DerKroon mechanics. They're not exactly cheap, but not horrendous either. One aspect of using drum-type flow diverters - make sure that you install them on the underside of the tank over the sump so that if the drum seal leaks (all diverter valves will leak at some point), the water goes back to the tank.

Saw these recently. They look nice but man, $$$$! Totally agree with your point about them leaking though - one of the reasons I never bought the OM since my sump is remotely located in the basement and I am not going to run the CL pump down there.

 

[dkeller_nc]

True enough, but the quality of the manufacture seems to have alot to do with noise. I wish the manufacturers for the aquarium industry would publish noise levels along with the other performance data -- we're putting these things in our living rooms! Have they not considered the spouse factor?

Oh, absolutely no doubt about quality of manufacture. Cheap pumps may start out fairly quiet, but always seem to get pretty loud on the "hum" scale after a few months of operation.

But - I mentioned this specifically because of Iwaki's/Pan-Worlds/Reeflo designs - they all use TEFC motors, and the air being moved by the cooling fan on the other end of the shaft can be quite loud.

 

[dkeller_nc]

Saw these recently. They look nice but man, $$$$! Totally agree with your point about them leaking though - one of the reasons I never bought the OM since my sump is remotely located in the basement and I am not going to run the CL pump down there.

Well, if someone were to really want a closed-loop system because of the size of their tank, the aesthetics, or just an interest in alternative systems, modern aquarium controllers do offer a work-around for not being able to locate the diverter valve over the sump. One simply installs the CL pump and diverter valve in a plastic tray that will catch and hold the water from a leak. A capacitive leak detector plugged into a aquarium controller can then shut the pump off if a leak occurs.

To be really safe about it, one could include a drain hole in that plastic tray, plumb that hole to a drain tube going down to the sump, and pretty much ensure that any reasonable leak won't drain the system of water.

 

[rlpardue]

To me (a simple caveman lawyer), it sounds like penductors/eductors convert high pressure pumps into high flow pumps in terms of their impact on water movement inside the aquarium. Does that sound about right?

 

[dkeller_nc]

Yep, that's a good summary. Some of the newer "hot rod" pumps include penductors/eductors in the body of the pump (search for "hydrowizard" on Reef Builders).

 

[Crusty Old Shellback]

Sorry but I didn't take the time to read all of the replys. But I'll give you my .02 cents from past experience with 2 C/L on my 400G tank.

On my 400, I too wanted to keep the powerheads out of the tank and so I plumbed it with 2 C/L's using a Reeflo hammerhead and barracuda.

The hammerhead was also plumbed into a large swimming pool filter and the return came back in from the bottom of the tank, hidden by my rock work.

The barracuda return was plumbed thru a Ocean Motions with 4 returns, two at the upper edge on one end of the tank and the other 2 near the bottom on the other end. The 2 lower returns had 45 degree PVC elbows on them to divert the flow up and away from the sand. The other 2 returns were just below the water level enough not to cause a lot of splashing.

The flow seems well enough with a nice "wave" acros the top when the flow was coming out of the upper returns. I could watch my LPS and anenomies sway back and forth.

Now to the down side. The electric bill was horendious. And after about 4 years of running the Ocean Motions, it wore a hole thru the "motion" drum and started leaking.

After about 4 years of running the setup, I replaced the whoel thing with 10 Korilla evolution 1400's and a red sea wave maker. The power consumption dropped from about 700 watts to 70 watts. The flow is more random with the wave maker. And I don't have to worry about leaks in the plumbing or OM 4 way. Basicaly dropping my electric bill by 100 bucks a month.

Also the C/L plumbing will begin to clog as stuff starts to grow inside of it. After about 3 years, a 2" pipe will become a 1" pipe which will drastically decrease your flow. There's no way to prevent it.

Hope this helps some in making a informed decission.