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Overflow box won't fill!


Daisy82

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Can anyone tell me why my overflow box won't fill? I have a box inside the tank with a drain that comes out the bottom, and my return pump in the sump that runs water to the top. The box will only hold about 2 in before it drains faster than the pump returns the water. Is my pump just too weak? It's a Quiet One, rated at 500 GPH.

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Sounds like the pump is too small, as you surmised. You have to take head loss into account when getting a pump. You don't have any valves closed off do you? Do you have a valve on the drain line you can close down a bit? What size are the drain and return lines?

Go here, and figure out how much head loss you have, then match a pump to your drain flow.

http://www.reefcentral.com/calc/hlc2.php

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Arg! That plumbing was a bear to rig up. I don't have any valves. The return pump has 3/4" tubing, and the drain looks like a little over 1". I measured and it's a little over 5 feet of tubing the water has to go through. I have about 10 in of slack - would cutting that off help anything?

Thanks for the link. I checked it out, but I'm not sure what to do with the info on head loss - any suggestions on what kind of pump to get, and how powerful it should be? (GPH)

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Let's assume you are capable of running 600gph through the overflow.

Two options really. Get a valve on the drain line to slow it down, or get a bigger pump. Assuming you don't want to redo your plumbing(understandable), a Mag 7/9 would be cheap and easy to pick up today and probably do the trick. An Ehiem 1260 would work too, but is more expensive and may not be available locally. I would call RCA/Tek/Fishy/Epic and see what they have in stock.

After looking at Danner's website(they make the Mag drive pumps) a 9 would be better I think. It'll do ~800gph at 5 ft of head loss. You'd have to add a valve to it to balance the flow and it will add heat to the system but will be cheaper.

A Ehiem 1262 will do ~500gph at 5 ft, will last longer, and be more reliable.

All things being equal the Ehiem is the way to go.

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Uh do you have a standpipe within the overflow box IE: Durso? It sounds like you have only the bulkhead down there from your description and that might be the problem. If you do have a standpipe is it a durso style? If so is it properly vented?

Would it be possible to post a picture of the overflow and another of the piping? I've heard several people say they use quiet one pumps and I would think all should be well even if it ran slow unless the durso was not properly vented and was instead "flushing". In that case it would allow the overflow to fill up and then suddenly suck everything out of the overflow box in one big "woosh".

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Yup, the water is basically falling out the bottom of the tank. I was talking with someone at a lfs and he told me to fit a PVC pipe to raise the level of the drain. Problem should be solved!

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Yeah I was going to say it doesn't matter what size pump you have as long as it is getting water into the tank the over flow will work if properly plumbed. The only issue would be if the pump was pumping more water than the overflow could drain. Sounds like you are on the right track. Research a Durso and you will be happy.

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