Ok, I have been reading and reading and reading threads about Ballast systems.   I am working on my second version. First version was a "factory" style install with the sprinkler valves with our 1100lb fat sacs (in the lockers), vented to opposite sides, aerator pumps "y'ed" into the vent to pump out. We don't use the Port side hardly at all so not worried about the speed over there, but starboard needs to be faster.   Second version: Dedicated Johnson reversible pump on the Starboard side to fill and empty. Keep the sprinkler valve and Having it supplement the fill of the starboard sac. Have a couple of manual shutoff valves to shut off the 1100 and direct water to and from an aux fill for extra sacs So now to my questions.   How important is it to vent to the opposite side? I have check valves so do I still need to vent to the opposite side? With check valves is there still a chance of siphoning water out the ballast? Does it create that much suction? Does the Johnson pump need to be stood upright or can I lay it down on its side? As I come up with more questions I will add them to my list.   Thanks in advance for your help and thoughts.