hi everyone. i have made the pvc pipeoverflow. it is 3/4" pvc. i tested this and it works well the only issue i have is this overflow can not handle my pump a eheim 1000 (240 gph with headlose). i researched and many have said that the 3/4" pvc should handle arround 300. i would like to stick with 3/4 since i all ready have it made. im am hoping that there is some adjustment i can make to the design with out having to go to a larger pipe size. i would realy appracite it if i didnt have to increase the pipe size since there is limited space in my 28 gallon aqua euro in the back compartments.

here is a piturce of the overflow i built on a 10gallon soon to be sump

Lowering the T joint *could* increase your flow, but it's already low enough that you probably would not get much. If you have it hooked up to flexible tubing, go with a rigid to-sump line with as few elbows as possible. If you're using a 3/4" union - use two 3/4" to 1" adapters and go with a 1" union. I've noticed that the hole in the center of a standard 3/4" union (and probably any other size) is considerably smaller than the 3/4" PVC size (as a ball valve would be for example) and this could be the limiting factor in your drain line.

And you can't see it from here, so make sure there's a air hole drilled in that cap. at 3/4" I wouldn't go smaller than a single 5/16" hole, I think I have a pair of them on my current one.