do you have to count headloss on a closed loop? i've got a QO 2200 i'm thinking of running as a closed loop for circulation but want more than 400gph(4' head) because it's a syphon doesn't the pressure equalize on both the input and output and negating headloss. basically, i'm asking if i put it on a closed loop, would i be getting 580gph or 400gph?