Plumbing head pressure

[Sebulba]

To eliminate the number of pvc pipes visible in my next tank, I want to run my return line through the bottom of the tank via a bulkhead. Once inside the tank, I would run about 6 inches of pvc straight up. This would allow sand to gather near the return line withour being disrupted. I would strategically place rock around, but not against, the pipe to cosmetically cover it up. The question is this, how much head pressure am I putting on the return pump considering that the return line is no longer dropping water in the tank from above, but actually pushing water against the 265 gallons of water in the tank. Tank is approximately 6 feet long, 2 feet wide and 3 feet tall.

Also, has anyone encountered a problem with this sort of setup. It seems to make sense to add filtered water to the bottom of the tank and push the waste water up into the overflows. Obivously I need a check valve in case of a power outage (probably use two check valves to be extra safe).
Thanks Troy

 

[Scooter12ga]

To simplify it, water pressure is only proportional to height and surface area. Since the surface area of your return pipe outlet is unchanged (i.e. a 1" circle) then you only have to consider height. Pretend that your return pipe ends right at the top water surface of your tank and you're set.

Example, if your tank is 20" deep, and your return pipe exits 6" above the bottom of the tank, then add an additional 14" of vertical head to your calculations.