# Call for Advice: 125 gallon DT/55 gallon ST Freshwater Setup



## Tekton (Mar 28, 2014)

Trying to make some more room for our freshwater angels, we decided to dive into deeper water with a 125 gallon display tank and 55 gallon sump (purchased tank, sump, and stand on Craigslist). Previously, our only experience was with a 30 gallon and 55 gallon tanks with cannister filters, but I wanted to move to a sump with this size class of tank.










Here is an illustration, removing all the cabinetry and giving dimensions, etc.










Figuring that multi-receptacle outlet looked like an electrical fire waiting to happen, I ripped it out, along with the shelf and all the outer woodwork. I have since replaced it with oak plank and oak-veneered plywood, and am building oak doors for the cabinets as well.










Realizing the weight is going to be an issue, and not having an ideal location to place the tank along a load-bearing wall, I am taking proper steps to reinforce the floor from underneath, so no need to warn me about that aspect. It will be done before the tanks are filled with water.

My main questions involve the plumbing itself. I've been poring over all the details online that I could find regarding sump plumbing, and have slowly but steadily been acquiring accessories and drawing up plans for the plumbing. I've simply never had a sump tank before and hope that some learned, experienced aquarists here can lend me some suggestions or advice regarding my design.

Here it is in its current form. All of the illustrated plumbing is 1" PVC (Schedule 40) except for the return lines in the overflow (above the bulkheads) which are 3/4". Additionally, the plumbing for the UV Sterilizer is 3/4" (didn't figure it would need 1" since it isn't pushing the kind of volume the return lines are). The pipes filled with green are the return pipes. The red pipes are drain pipes. The neon green pipe is dedicated to the UV sterilizer.










A few system notes regarding accessories I've acquired so far:

-The media cabinet/biowheel is a Tidepool 2 that I cut the front section off of. I just wanted it for the biowheel and the media cabinet, so I didn't have to build those things from scratch (also got a good deal on the thing at a local fish store)

-The pump is a Fluval SP4, which nominally pushes 1823 GPH at 0', 1672 GPH at 1'6", 1548 GPH at 3', 1347 GPH at 4'6", 1281 GPH at 5'9", 1135 GPH at 7'2", 805 GPH at 9'5", 499 GPH at 10'8".

-Standpipes are Hofer Gargle Buster design.

-Coralife Turbotwist 6x 18W UV Sterilizer

A few specific questions that I have yet to find good answers to online.

-As illustrated, basically every joint in this system is going to be solvent welded with PVC cement (except the ones connected to pumps and accessories). I'm curious about the 1" threaded x1 slip" adapters threaded to the bulkheads though. Since I can't fit Union Joints beneath all the bulkheads I figure I'm going to have to saw everything off if I ever have to remove the plumbing anyway, so I didn't know if it was worth it to use nylon tape on these particular joints.

-There seem to be a lot of opinions on how much water should be channeled through a UV Sterilizer in an hour. I was thinking about getting something like a 500 GPH pump to run this. Does that seem reasonable?

-I haven't done any kind of volume studies on the plumbing or overflow yet, as I figure modifications will be made to the plan based on suggestions from forum contributors. I realize the baffles will probably have to be adjusted to make the compartments different sizes, and possibly the heights adjusted, to account for backflow in the event of a power outage, etc. I could certainly use some advice on that process if anybody has expertise there.

-For purposes of power-outage situations, do I assume that ALL the water in the overflows is going to end up in the sump, or only the water that will drain in before the water drops below the stand pipe drain holes? I simply wonder because I'm under the impression that the standpipe mated into the bulkhead isn't sealed or glued in any way, so I wonder if leakage just above the bulkhead is a possibility that has to be accounted for.


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## Thalas_shaya (Mar 10, 2014)

I highly recommend having a read at Wet Web Media in their sump plumbing FAQ: http://www.wetwebmedia.com/pbmarpipefaqs.htm I know it says it's for Marine systems, but the principles of plumbing are the same for Marine and Fresh, and since sumps are near ubiquitous in Marine setups, that's how WWM files them.
They also have a great section on Sump Design: http://www.wetwebmedia.com/sumpdesfaq.htm

As for the nylon tape question, a recommendation that I picked up along the line somewhere is to use a thin layer of silicone on the male threads of sump connections, and on the underside of bulkhead gaskets. That is easier to work with than the tape in these tight under-cabinet setups, seals equally well, and is more removable than PVC welded connections. I have some in my tank that I'll have to saw off if I ever have to remove them, too, for space limiting reasons.

I have no personal experience with power outage, but my drainpipe (a Durso design) is set up like yours - just slipped with no seal into the bulkhead - and it nominally only allows the water above the drain holes out. When I was leak-testing my tank, the water in the overflow box did NOT continue draining (at a meaningful rate) once the water got below the drain hole.

Also, 1" lines are insufficient for a system this size. In practice, they can only drain about 300 gph (safely) via gravity, which would give you a total of 600 gph, which would just barely be sufficient for your tank's circulation needs and won't be able to keep up with your pump without forming a siphon. 1.5" would be a better fit (as they can do about 750 gph via gravity) and with two of them you should be able to keep pace with your pump. Also, if your drains are too small, they'll get really noisy (shoving lots of water through a too-small hole leads to gurgling off/on siphoning, etc). 2" lines will give you more drainage capacity (1300 gph each, meaning if one got blocked, the other would prolly be able to do the job solo, a nice redundancy consideration) and will run quieter, but that might be overkill.


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## Tekton (Mar 28, 2014)

Thank you for the thoughtful reply. I'll check out the articles you recommended.

Regarding the 1.5" plumbing. Are you referring specifically to the drain plumbing, or the drain and return plumbing? The tank came pre-drilled with 1 7/16" and 1 3/4" holes, meaning I can only use 3/4" and 1" bulkheads. That creates a natural choke-point in the system, and I'm wondering if it does any good to have wider plumbing anywhere in the circuit with those choke-points in place. I could easily use 1.5" plumbing beneath the bulkheads, but does it gain me anything if the water is choked down to 3/4" in the supply lines and 1" in the drain lines at the bulkheads?


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## Thalas_shaya (Mar 10, 2014)

Ah... I missed the detail of the already-drilled holes. I think with those choke points in place you're stuck with the sizes you have for drains. 

I have to tell you, when I first saw the photo I fell in love with the built-in electric sockets and the shelf on the left. But I see your point about taking them out as fire hazards.

Look forward to hearing/seeing what comes of this setup!


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