Kessil

Closed loop for flow?

kinetic

kinetic

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I've been thinking about the next tank build, and I've thought about doing a closed loop for flow. I know we're all about the small powerheads and gyres these days, but I can't get over how clean a closed loop would be.

I'm thinking of two DC pumps with one input and one output each. I'll use one of those varying outlets to give it some randomness, and I'll put the pumps into probably some kind of ramping pulse. The pumps I'll tuck under in the cabinet so they're totally out of the way.

I get that you can't really adjust the height, and maybe it's hard to clean around it vs. a pump you can just remove the magnet, but that doesn't really bother me too much. Plus, less noise since I can hide some nice quiet DC pumps in a cabinet.

Any suggestions? I'm thinking of possibly drilling a Waterbox Peninsula for it.
 
kinetic said:
Any suggestions? I'm thinking of possibly drilling a Waterbox Peninsula for it.
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My main thought is it might be better with a new tank to do that. So I'll take your waterbox peninsula off your hands and you can try from scratch :).

Following since I've been thinking about this too. Back in the day before I dropped out they were popular. Now on my return they seem unpopular. I don't know the details on why.

I've been thinking for the peninsula I eventually get it'd be nice to have the far side have a closed loop adding water movement without powerheads. I was thinking with the ability to 3d print tubing in PET-G, you could do some interesting stuff having the loop output come through the bottom of the tank, then use custom shaped tubing adapters to point the line on various different ways, hidden inside live rock structures.

It could look pretty natural/hidden if done right, since the tubing wouldn't need to be straight runs due to the printed pieces.
 
This recent build I did employ closed loop. I used 4x 1.5” SCH80 bulkheads. The two inner holes are intakes. The outer ones are returns. The returns are split into 8x 3/4” Loc-Line nozzles hidden within the rock work. I used Abyzz A400 on Random mode.

DBD6FDF6-F002-47BB-9B6D-C6C59B9B5116.jpeg
 
My only concern would be long term bulkhead issues. Probably fine as long as you make sure the nut is nice and tight every 6 months or year or so. Also a little scared of bumping the intake/return nozzles and putting pressure on the bulkhead/holes. I do like the hidden flow and no cords tho!
 
Having holes in the bottom of the sealed box of water makes me very nervous. I like to have the worse-case scenario of a failed joint, backflow down a pipe, failed one-way valve, etc not be complete catastrophe.

Also tanks get progressively harder to maintain as everything grows in. The thought of having something hidden in the coral/rockwork that I have to get access to to clean or replace makes my skin crawl.

I think closed loops are relics of a time long passed when we didn’t have small efficient power heads. Unless you are a public aquarium or have @robert4025 on call to maintain your system…
 
JVU said:
Having holes in the bottom of the sealed box of water makes me very nervous. I like to have the worse-case scenario of a failed joint, backflow down a pipe, failed one-way valve, etc not be complete catastrophe.
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Agree here. My only regret on my big tank design was putting the hole in the bottom for large water changes, that I don't do. Bulkheads have for me been the weakest link in leaks multiple times.

Modern powerheads are adjustable and can be hidden on back walls, in rock piles, and more importantly to me, can be taken out of the tank and debugged without shutting the system down.
 
I would employ CL only on very large system. Anything less than 8ft, you can get away with it using off the shelf circulation pumps. However, if your tank has super large footage to cover, using a bunch of those pumps just doesn’t make sense, even if you can hide them. I’ve done this before and doesn’t work out well in the long run. Hiding a bunch of cables in the rock work are always easier says than done. Beside not many modern pumps have THAT long enough of cord to allow you to snake them through long stretches of rocks.

Take for example the tank I just posted. I needed to have 8 different directions of flow for maximum flow efficiency. Imagine burying 8 power heads in the rocks and hiding the cables in a 10ft tank and then having to take them out every 3-6 months to clean them and putting them back. Yeah, that’s not gonna happen. You can’t pay me enough to do that sorta stuff….lol
 
Thanks everyone, that's really great info!

Interestingly, I was just thinking of doing a closed loop on one "wall" of the tank, no bulkheads/etc on the bottom. But maybe that defeats the purpose of a CL, and I might as well just go with some powerheads.
 
I had a 240 with a closed loop for 8+ years, never a problem except electrical. Used Schedule 80 and Quality bulkheads with 2 input lines capable of full flow just in case one got clogged or a LBTA decided to cover one. I did have them on the back panel vs the bottom panel so even if they failed, more than 1/2 the water would still be in the tank. Didn't want them inside the rock-work so I could clean and replace the strainers. Inside the rock work while clean looking seams like a place to catch fish adn other critters. Used an unglued slip extra large strainer for each bulkhead. The return plumbed into an over the rim manifold with a bunch of PVC Ts with threaded ends. I could install loc-line fitting in (I still have most of the loc-line fittings if you need some 3/4) an almost unlimited orientation with no visible impact to the tank. Tank had a single big Tunze on either end to make the manifold outlets act more random and the manifold returns could be pointed to any coral in need of flow. Was awesome and I miss it. Will 100% do again on a large tank with a canopy.

If installed correctly, you should not have leaks. The pipes in your walls are are at higher pressures then what you can get from your tank. Put a tray under the pump as it will more likely leak a little then the bulkheads and it catches the water when you service the pump, which is like never. I had a Dolphin Reflow pump is I remember correctly - or something similar, but would use an Abyzz if I did it today of course.

Was really nice having super random flow with almost no plumbing visible. The big Tunzes at the ends were really the only thing visible and disappeared in such a big tank. Was also Silent which is very important to me. I never serviced the CL pump (maybe in 2 years as the seals would start leaking a tad on those pumps making a salt crust on them)


old article

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not my photo - from article. Shows example manifold.

I would 100% do this with a peninsula. Close Loop intakes on the same back wall as overflow with a return manifold going up and over the top the tank with outlets where ever you need them. Variable DC pump. Add a small strip around the top of the tank to cover pipe yet keep the tank open - like a molding. Add a few other power heads where you can hide them. If you went 2 pumps, you could pipe the second "underground" inside the tank / under the rocks/sand on the bottom and use the PVC to hold the rock work up. No holes in the bottom to deal with, everything coming through the rear wall.
 
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The idea of sticking a powerhead inside a rock never entered my mind before. That's really interesting, though has the issue of needing to sneakily get the cord in, as noted. This is probably an awful idea, but running a couple DC lines into the tank, through the bottom, seems like it could be pretty interesting.

Use waterproof fittings, put in a waterproof box. All you'd need to hide in the rocks would be a cord instead of a pipe. Grommet + silicone the cord at where it enters the tank.

Alternatively drill a 1in bulkhead low in the tank. Attach it to a flexible pipe with an exit point above the water line. You could then run cables through and hide them.

That might be what @robert4025 is talking about, but I never considered something like that, and I find the idea very interesting.
 
richiev said:
The idea of sticking a powerhead inside a rock never entered my mind before. That's really interesting, though has the issue of needing to sneakily get the cord in, as noted. This is probably an awful idea, but running a couple DC lines into the tank, through the bottom, seems like it could be pretty interesting.

Use waterproof fittings, put in a waterproof box. All you'd need to hide in the rocks would be a cord instead of a pipe. Grommet + silicone the cord at where it enters the tank.

Alternatively drill a 1in bulkhead low in the tank. Attach it to a flexible pipe with an exit point above the water line. You could then run cables through and hide them.

That might be what @robert4025 is talking about, but I never considered something like that, and I find the idea very interesting.
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www.marineandreef.com

Tunze Stream Rock 6200.250

The Tunze Stream Rock 6200.250 is one of the accessories that make Tunze pumps so easy to work with. The Stream Rock is primarily used to hide Tunze Nanostream powerheads, but it can also be used to position a pump on the bottom of a tank.
www.marineandreef.com

I still have one of these, but for the bigger tuze, not Nano. Old School Makes a good garden rock.
1652142808462.png
 
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