Im having trouble trying to figure this out. Im in the process of ordering a standpipe from the guy that mkaes them. We are having trouble deciding where to put the hole. He seems to think that with my 1.5in bulkhead it wont fit in the internal overflow unless the hole is ion the exact right spot. can anyone help me out on this issue. Where does the hole exactly need to be so that the standpipe fits perfectly. BTW, the internal overflow im using is the two sided one from wetdryfilter.com. i think its dimensions are 6x6 or 6x7. thanks