I would just purchase a hob like the cpr model. The reason I say that by the time you get the tank drilled and get a custom overflow and then put baffles in get the pipes and then the return pump you could have just bought a 12in cpr hang on. That is just my opinion. I feel that if you want to try one go for it, but I cant begin to tell you how to do one since I have never done it myself. Good luck. If you do decide to do it post pictures..