plumbing overflow box with two outputs

would it restrict the flow if i plumb the outputs both to one pipe into the sump? i have 1 1/2" bulkheads on both the overflow box is rated at 6000pgh. i have a mag 12 return pump. for my 135gallon tank and 50 gallon sump.

It will limit the flow a little. It's much better to have 2 drains but if your only able to do 1 it should do.

Is this a drilled tank or are you using a hang over the back overflow box?

Depends how large the one pipe is.

hang on overflow box

Are you planning on running any other type of filteration in that tank?

for now just my overflow box to the sump with my internal skimmer.

I honestly don't think that's going to be enough filteration on a 6 foot tank. I doubt it's going to drain fast enough to equal the pump your running on it. As well as pull enough from the tank as far as debris goes within the 6 foot area to that 1 box.

Are you able to locate another overflow box? That would help out a ton

what ??? why not?

that box is rated for a 250gallon if i remember right.

It's not enough water flow.

Eack overflow box is rated at a certain gallon per hour and your is at 600. Your pump is much more powerful than that and it will drain the sump faster than your 1 overflow box can drain water into it. With too much water going into the tank and not enough going out you know what the outcome is.

6000ghp

I've never seen an overflow box that's rated at 6000 gallon an hour. Do you have a link to it?

im sorry 1600gph

i got the biggest one they make
eshopps hang-on overflow boxes

If you have the PF-1800 that is their largest one they carry. Although they don't show it on their website. Flow wise it will work for your tank but only if it's being used as it's designed for. If your only using 1 drain tube your limiting the flow into the sump, basically cutting it down in half.

What I think the best thing for you to do is to use both drains into the sump. Worst case would be to at least hand the 2nd drain in the sump if your filter stack won't accept a 2nd one. I'd also add a power head or 2 inside the tank to direct anything in the water towards the overflow box sine it's draining from only 1 area in the tank.