found something out this weekend after finally getting to use my new ballast system, I added one way valves to all three vents. rear bag sucked down like a vacum bag--awesome results. IBS bag did the same.
this is where it gets interesting.
I got home and got the boat wiped down and stowed into the garage, all was nice and quite and I swear I could hear the boat burbing, locate source of burbs to the IBS bag that is piggybacked off the center tank, undid the quick disconects from the IBS and heard a long vacum of air entering the center tank, I then hit the center empty button, about 5 minuts later and the center tank was empty and the garage floor was getting a nice lake water rinse down. May have to remove the oneway vent or get creative allowing air to enter the tank as Im thinking a tank needs to vent to empty. Think I may add the directional valve and once the IBS is flat switch it so the tank can vent freely.
you should be able to "Wye" the center hard tank after the CV from the IBS and that may fix it . May not suck the IBS flat after it empties into the hard tank and the air lock will realease when the water gets low enough.
maybe it's an issue that arises with a hard tank vs bag?
I'm heading to the lake on Wed to see if I have any water in the tank.
This also depends on the type of material and thickness of the hard tank. It might be a thin soft plastic and your doing more harm with no vent on it.
I cant say for sure though, i have delt with the new hard center tanks Moomba is using, i will try to learn a little more about them to share but i would be leary on messing with the factory hard tank system unless you really understand everything they did for it.
You need to add a spring loaded check valve and a tee in the hose between the hard tank and the IBS. The flow direction of the check valve would have to face the tee. There is no need to attach a hose to the other side of the valve, it is only used to bring air into the hard tank. Once the IBS is sucked flat, the vacuum pressure will cause the check valve to open and allow air to enter the hard tank, and allow all the water to be drained out. Leave the oneway vent where it is, and don't bother adding a directional valve. This way it will be fully automatic.
Note: It must be a spring loaded check valve.
Drew and I have been unable to wrap our brains around this to make it fully automated. Neither of us wants to deal with valves or anything manuall. Perfect written discription, as im fully able to "See" this.
Just got a tee fitting from wakemakers 2 days ago and I think I have one of these spring loaded check valves at home from trying to mod the 08's system, now I cant wait to get home and rummage thru the ballast parts drawer.
Ballast mod session tonight--gotta be at least a 3 beer/3 pizza slices job.