I don't know what size sump pump to get

[funkngroovy]

I am setting up a 20 Gal cube and using an old 20 gal tank as a sump. I have no clue as to what size pump i will need. Do you think I can get away without any other powerheads if I can bring the inlet up through the bottom of the tank and tee it off in 2 directions???

 

[TimSchmidt]

You want to make sure that your pumpt does NOT exceed the overflow capacity of your tank. Other than that a lot of people aim for 3-5 times turn over. (90 gallon tank = 270 - 450 gph pump after head pressure calculated in). Do a google search for head calculator or pump calculator (unless we have one here).