Plumbing Dual overflow, single 2" hole...


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Dec 20, 2020
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Just picked up a used 220 gallon tank, it is set up with dual corner overflows, one single hole in each overflow that is 2". Drilling any more holes is not an option, I will be going with a Durso style stand pipe. Finding 2" PVC pipe & fittings is looking a bit difficult (wanting to go with colored PVC, 1.5" is the biggest I can find in Canada). What I am hoping to do is run a reducer to 1.5" on both sides of the bulk head, so both the Durso and pipe down to the tank will be 1.5". I know this will reduce some flow, but should still be well over what I am looking to run. Just wondering if there are any other issues that may come from this or if there is a better solution.

Return pump is a Jebao 18000, I will have it dialed down until I start using a manifold for reactors, UV and possible Frag Tank. Second question, pump has the main return of 1 1/4" pipe, my plan it to run a single 1 1/4" pipe up to the tank, then make a short manifold of of 3/4" loc line fittings. From some rough calculations, I think with the 5' or so of head height, dialed all the way down, it will be running around 2000 gph. How many loc line returns should I use? 2? 3? 4?



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Apr 17, 2020
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2 1.5” drains will give way more flow than you could ever need. I also bought a used tank and it came as you describe. I ran one side an an emergency drain with a stand pipe slightly higher than the other side and then run the other side completely flooded with a gate valve on the return. The flow into the second one is a very small trickle but will act as an emergency should something clog the other one. It kind of defeats the purpose of dual overflows but I find being able to dial in the flow with the gate valve and having a silent overflow is much more beneficial. Just my 2 cents! Also my 2” is reduced down to 1.5” and with this set up my 3150gph pump with 2-3/4” lock line returns from a 1” manifold and that 1 side with the gate wide open is way more flow than my pump can supply it.

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