Drilling a 75

[gogregerson]

I want to drill a 75 and have a few questions. I plan on drilling one hole in the middle for an overflow and two holes for returns, one on each side of the tank. Question is, what size to make the holes? Where is the best location for the holes?

[storrisch]

do you already have all of the equipment for the returns? the main thing is going to be GPH so as long as you can return the water as fast as it is coming down..... I think bigger is better works when it comes to drilling for bulkheads

[David Grigor]

I'd reconsider drilling the holes for the returns and just go over the top. Gives more flexablity for future configs etc and really the head less is pretty minimal on a tank that size. Also even as high up as you can drill the tank, it will drain more water in a power outage than necessary. I did that on the 320g tank and really regretted it later.

But if you go through with drilling the returns, I'd personally go with 3/4" for the returns and 1.5" for the overflow. On a 75g there shouldn't be any need for larger then 3/4" returns and going larger will mean the tank will drain even further in a power outage.

[spsick]

I'd reconsider drilling the holes for the returns and just go over the top. Gives more flexablity for future configs etc and really the head less is pretty minimal on a tank that size. Also even as high up as you can drill the tank, it will drain more water in a power outage than necessary. I did that on the 320g tank and really regretted it later.

But if you go through with drilling the returns, I'd personally go with 3/4" for the returns and 1.5" for the overflow. On a 75g there shouldn't be any need for larger then 3/4" returns and going larger will mean the tank will drain even further in a power outage.
I was going to say the same thing, returns over the top really work better, use 2 street elbows, then a regular, that will make minimal drainage when you turn off the pump, just a gallon or 2.

[gogregerson]

Thanks for the advise.

[rihanssu]

yeah i drilled my return on my 40 gal and i hate it now!