Drilling holes for overflow and return questions

[tbone68]

I am planning on drilling some holes in my acrylic tank for 2 overflows. I plan on putting the overflows in each corner of the tank but I'm unclear where I should drill the holes-on the bottom or the back of the tank? Also, what is the general rule of thumb for the proper size of the holes? My tank currently has one hole drilled into the back of the tank about 2 inches down from the top which I plan on using for the return. Is one hole sufficient for the return?

-Tony

 

[Devilish]

Probably gonna need a little more info. What size is the tank? What size is the hole that is already drilled in the tank. What do you plan to do with the tank (FOWLR or Reef) If you have 2 overflows, I would think that you would need 2 returns to handle the flow. As far as the back or bottom, I don't have much experience drilling tanks but I've seen them either way, drilling the bottom would probably lead to easier plumbing though.

 

[tbone68]

The tank is 100 G. I believe the hole drilled is 1.5 inches. I plan on starting off w/ FOWLR and transitioning to a reef tank later. Do you know if there is any other advantage to drilling the bottom other than making the plumbing easier?