well i started to do the pluming on the rear of the tank, and filled it with freshwater, and so far so good. the top pipe is 1'' 1/2 drain to the ampmaster 4700 for a closed loop, then below that is my chiller intake 1'' then below that is the return from the ampmaster , 4 1'' returns then you have the 2'' drain into the sump, you cant see them but for the sump return's i had 4 holes drilled in the top braceing of the tank 1'' each and ill have two iwaki 100 , one on each side for sump returns.