I'm going to install an inwall see-through saltwater fish-only tank. The tank measures 60" long, 8" wide, and 24" tall (45 gallons). I am planning to install a 3/4" drain high on each side with bulk heads connected to pvc pipeing in the wall down through my subfloor downstairs into a sump(old 75 gallon scratched up and drilled 100 times into tank) that will hold refugium, skimmer, etc... I was thinking of drilling a hole center of the in wall tank at the bottom, with another bulk head for my return. I would then connect a tee above that with 1/2" or 3/4" pipe running horizontal to the tank floor with 1/8" or 1/4" holes drilled every 2" or so with a plug end cap at each end; or I could use the undergravel system screens by themselves. This all would be buried by sand or whatever substrate I decide to use. I would also of course use a one way check valve right after my pump so the tank wouldn't completly drain in an event of a power failure. My question is that, is this a good idea with filtered water entering through the substarte pushing the waste up towards my drains or will it screw up the biological sytem or release bad gases, and could this cause failure of the tank strentgh itself? Keep in mind my sump could hold live rock or whatever I may need to support further bio. Thanks, Revango