in my opinion, i would just drill the thing. if you're handy and have some tools laying around, just buy the bit and remember to drill it very, very slowly. wait, is the is a glass tank or a acrylic? acrylic will be much easier to do, just attach the right bit to a drill and drill it out. if it's glass, you will probably need to have it done, unless like i said earlier, you're handy. the way to do it, is to buy, the bit, this metallic sand stuff (don't remember the name) but it is used for the bit to drill out glass, and you will need to use a kind of tape that you can pile up in a cirular form to make a little pool where you will fill with water and that metallic stuff. and then drill as slowly as you can and hold it steady until you punch through the glass. you can also probably have it drilled out at a glass shop for like 30 or 40 bucks, maybe less. then just buy your corner overflow and the pipe fittings. all in all, you an get this part of it done for under a 100 bucks. then it's just a matter of getting the sump and running the pipes. but after it's all said and done, your it will look cleaner and it will be much quieter since everything will be under the stand.