Top drilled holes and specs

[JeffInKentucky]

I searched previous rap threads & couldn’t find an answer, but feel free to redirect me if I just missed it. I’m going to setup a 180 gallon (72” long) display tank with a sump. I want to hide all pipes, filters, etc. I will also be installing an Aquadecor 3D background, which can be customized for the intake and return pipes. My question is with regard to pre-drilled holes for intake and return. I’m assuming that holes on the top are better than bottom with regard to preventing back flow and flooding of the sump because you can set them so that only a max amount of water can drain. Correct? If so, what would be the ideal placement with regard to distance from top and sides? Thanks in advance.

[captainandy]

An inch below the waterline, Also investigate a true union one way valve. Can be a major flood protector when using a sump

[JeffInKentucky]

An inch below the waterline, Also investigate a true union one way valve. Can be a major flood protector when using a sump

Thank you very much! I did not know about true union valves.

[FischAutoTechGarten]

I did slightly closer to the top edge for both, but I rigged up jigs so that I wouldn't crack the glass while I was drilling.

You can go much lower, if you utilize an elbow pointed upwards to set the height. However, you don't ever want those elbows popping loose, as you will then drain wayyyyy down, so make sure that they are secure.

The advice captainandy gave you is very, very sound!

[JeffInKentucky]

I did slightly closer to the top edge for both, but I rigged up jigs so that I wouldn't crack the glass while I was drilling.

You can go much lower, if you utilize an elbow pointed upwards to set the height. However, you don't ever want those elbows popping loose, as you will then drain wayyyyy down, so make sure that they are secure.

The advice captainandy gave you is very, very sound!

Thanks!