overflow v return

say, for example i already have a return hole size of 1/2 inch drilled in a tank. if i want an overflow hole put in, would i want the drain hole the same size as the return or bigger? and this 1/2 inch return is on a 40 gallon tank and i figured although it isnt a lot of water going through the sump per hour, it is better/good for it to go slow so the skimmer can process more. any comments?

the tank is exactly like a cadlight, just 40 gallons, a cube, and a different filter process in the back. If you are looking at the front of the tank, on the right side of the tank behind the divider i am drilling the overflow hole and the return is already drilled in the divider. if you follow this, please share your input. i had shoulder surgery yesterday on my right, dominant arm so its hard to type and describe well while on pain meds

if you look at the picture below, its the same tank idea but opposite, the overflow on the right and return on the left. it would drain on the right side of the tank, leaving the dividing acrylic piece in and letting that be the overflow device, going to the sump and pumping the water back in by connecting the return pump from the sump to the return pre drilled in the dividing acrylic piece.

again, the drain hole wont be cut in the bottom but on the side of the tank, right near the bottom. do you follow? could this work and how big should the drain hole be?

 

The size of the overflow doesn't matter and only sets a max limit to the gph that can flow through the sump. The return pump is what will dictate the actual overflow rate. I would use a much larger hole than .5". I would 1.25" or at least 1" drain. I like to use a 3/4" return, but that depends on the pump and head level you have.

 

thank you for your response, i know it was confusing but you answered what i needed. i would like a bigger return hole as well but its already drilled in the flimsy acrylic separator and i cant make it any bigger than it is. again, thanks for your help and now i know to make the drain hole bigger. what is the maximum size pump/gph you would send through a 1/2 inch pvc pipe?