Rigos right.If your tanks not drilled,just get yourself a HOB overflow.A lot of pre-built sumps come with the HOB overflow.
Pro-Clear makes one thats rated for like a 125.It comes with the overflow box and supply hose.It also comes with 5 or 6 feet of clear vinyl tubing to use on the return.All you'd need is a good pump and some stainless hose clamps.
BTW,that is what im running on my 55.