Ballast not draining all the way

[idaman]

I know I have seen this before, but can't find it in search, so sorry for duplicating it.  Plumbed in my bags to the rear lockers and having some issues.  First, I know others would say trash it and go with reversible pumps, but the budget doesn't allow that right now and I already had the pumps.  Pumps setup as wakemakers pic, except I did put a check valve on the drain lines since they go into a Y connector with the vent line.  I originally had the drain pumps mounted up high and realized that gravity didn't work that way so now they are just laying on the floor at the rear of the bag.  All the water is not getting out of the bag and seems to be filling with air.  I believe I need to move the check valve to the vent lines so it doesn't let air in, but want to save myself the time and $$ of cutting hose if that is not what is needed.  Any suggestions?  Thanks

[malibu2004]

Call wakemakers.