How fast does water drain?
 

Hi everyone, just in the process of matching pumps to new tank, I have a 125 galllon tank with a external overflow box built, it has an 1" hole, I was just wondering if anyone knew how fast that drains, it will most likely have a few inchs of water built up in the overflow box, the overflow box is about 4"(depth)x8"(long)x10"(high).

Thanks everyone.

There is only one hole in the overflow box? Usually there are two. Most medium-sized tanks are drilled 1" for return, and 1 1/2" for drain. That's how my 90 is drilled. I wouldn't want a 1" drain on 125 gallon tank...that's too small. 1" will only handle 600 gph, and it won't take much to clog up. You should have room in the overflow to drill a second hole no?

This chart may help, but as Myka said I wouldn't try to push more than 600GPH through a 1" line so don't take those numbers as gospel.

http://flexpvc.com/WaterFlowBasedOnPipeSize.shtml

sorry guys, yeah there is a second hole, but I don't plan on using that hole, I am just gonna plug it up with a bulkhead cover till I need it. But yeah you guys might be right about the 1.5" hole for drain, can't remember exactly, but i think there is only a 1" clearance in the pipe right?

If you have two drains, why not use them both and do a Herbie style silent drain? That's what I have going on my 90. The 1 1/2" bulkhead is my main drain with the 1" as my backup drain. :)

+1 on this suggestion!

Also...there aren't easy answers as to how much water will drain through a particular pipe size. How much goes through depends a LOT on how much water is above the hole, and how much vertical drop there is to the sump below.

hehe I am just too lazy to do all that plumbing work, and the tank is in a place where noise isn't a factor.

so yeah is there a chart that can tell me what kind of flow overflow boxes have with different size holes?

If you have 2 holes i would use them both. Your going to have to buy 10' of PVC, glue and primer anyway so why not use it?