I want to make this overflow for my 110g tank. I am wondering...do I need one on each side or just one? The middle of my tank has glass which will not let me put the over flow in the center of my tank, so, I would have to put in one either side. I want to use the 1' like you did. What size tank are you putting these two over flows on? If I decide to use two, what size pump and if I use only one, what size pump? Thanks for any help in advance!