The plumbing is 1in. As for changing the plumbing, I have no intention of doing so, Just wanted to make it known I knew about the 3 over flow methods to eliminate those suggestions. LOL Call it a preemptive strike if you will. As for the rigid tubing how would one put that in since the overflows go through the back of the tank? You suggesting a T on the back of the bulkhead and capping the top and then drilling a hole to insert tubing into?