@ Jeff... Yeah, I thought about the same thing as far as having my vent through the drain line since I'm using aerator pumps. From reading some of the other threads, by doing it this way (venting through drain line) you may be putting undue stress on the sacs before any water comes out the drain through hull for venting purposes. Not saying it can't be done. So, I pretty much went with what Wakemakers suggested. That is running separate vents and drain lines. Only thing I overlooked is the through hull location for both the drain / vent. Mine are too far back toward the stern and sit really close to the water line when fully loaded.
My boat only came with the center ballast, no rear tanks so I had to add the drains/vents for these. In order to keep everything symetrical, I spaced them evenly next to my bilge thru hull. Bad idea since the bilge thru hull sits way in the back. Never really took notice until I dropped the boat in the water and started filling... So in order to avoid taking on water I'm going to add check valves throughout. It may not even be an issues since the sacs will be taking on the water, but I just don't want to take on any water when not purposely filling the sacs.
@ Dave...your thread was a huge help man and your wake looks unreal!!.. lol .. Probably the main reason I didn't go with the 750s is I would've had to upgrade my prop which will be next years project. As it is right now: 540# in the walkway, 300# stock, 200# lead, and the 400#s in engine compartments it is a bit slugish getting on plane. I think for now I'm good and really just like the luxury
of being able to drain / fill with the touch of a button. BTW, did you ever figure out how to entirely drain the sacs? Originally I was going to locate my drain pumps toward the stern, but decided not to since they'd be crushed when the sacs are full.
Overall I'm pretty happy with the way it turned out.