Thanks Turf! I have a system drain at the exterior shower, but I'm going to think about the drain a the suction port now. Hmm... Two drains better than one?? I thought the bypass for the filters would be good to keep the system running while I change/clean the filters, but that's possibly unnecessary because filter swaps should take an hour tops I'm thinking. The bypass around the pump was a way to direct water sucked up at the suction port and direct it into the fresh tank if need be. Im not sure just yet how I'm going to make this system more refined/simpler, but thanks for giving me a push.
P.S. I have the same setup! 5.9 and AT 545. Thanks again Turf!