basic overflow questions

[clax66]

Hi guys, been reading a lot but need some clarification of a few things. hope you can help out.

I recently bought a 210 gallon aquarium that has a 2 3/8 inch hole in the back corner and a 1 3/4 inch hole back middle. Both holes are on the bottom of the tank. I have been assured that the bottom is not tempered. I am trying to decide between two scenarios.

1) cover the holes and drill new holes in the back of the tank for internal overflows in the back right and left upper corners of the tank. This would cost more due to having to buy overflow boxes glass-holes style.

2) buy some acrylic from Lowe's and enclose the hole with an internal overflow that covers the back corner of the tank from bottom to top. I would use a durso style standpipe and maybe drill another hole in the overflow area for the return.

My questions are:

1) if I build the overflows in the corners will silicone adhere to the acrylic well enough to make the overflow water tight? The acrylic will be 1/4 inch and 5 inches x 10 inches x 24 inches high.
2) do I glue the standpipe in the overflow or just gently force it into a slip bulkhead with some plumbers glue/tape
3) once the overflows are in how difficult is it to remove a standpipe space wise. Maybe I would never have to do this? It seems very confined with a 1 1/2 inch pipe and possibly a 1 inch return.
4) Is it more desirable to have holes drilled in the back or bottom? what is the general consensus?

Lots of questions I know.

[Entropy]

[welcome]

I would make the overflow out of glass panes. The silicone will hold better IMO. Glass Cages does this so you might want to look at their site for ideas. You can paint the overflow wall or cover it with black acrylic (with teeth cut out). The standpipe does not have to be glued since it is the overflow wall itself that holds back all the water. The standpipe in this case just holds back the water in the overflow itself, so if it is leaking you are just talking the small amount of water in the overflow (a gallon or so I am guessing). Hopefully your sump has more overflow capacity than what is in the overflow. :)

IMO the hole in the bottom of the tank is going to flow more than a hole in the back, but both will work. Another option you might want to think about is using the existing holes as a closed loop, and then just add whatever you want since the bottom is not tempered.