overflow box size?

I bought a 240 drilled tank off craigslist the other day. Questions I have
1. the holes are on the left and right side of the tank - however they are in the middle, not the front or back
what size boxes should I be looking for? I have a 1200 and 900 for return pumps
2. and is it ok if I 90 it so the boxes will be in the back corners?

 

The holes are in the middle? As in the bottom of the tank? It was probably set up as an island, or they could be returns that just ran HOB boxes, or both.

And yes, you can run piping to wherever you want. I would use a full corner overflow though to keep it from being too unsightly.

 

If you don't prefer the existing location you could plug them and drill the tank where you would like.

 

Prefer not to redrill, would it be okay to just use one of them for a corner and use the other one for a return??

 

Those holes are likely there for a closed loop, not for drains and returns.

 

Are the holes the same size? That might give you some direction. Generally speaking, if you have both drain and return holes, the drain holes are larger.

That being said, our 210 peninsula setup has four holes in the bottom centerline of the tank, which are closed-loop returns. The drain for the closed loop is a spa screen in side of the overflow box wall that runs out the bottom of the tank within the O/F box.

 

Picture would help.