So on my Mobius V 2000 i have two hard tanks either side of the engine in the rear, and one ski locker fatsac which i added myself last summer.
I have also added 6 x bags of sand to the bow under the seats, which makes the wake just right.

I am thinking of replacing the fatsac and bags of sand with one or two fatsacs to take up the whole ski locker.

Problem is, the fatsac never really empties, i guess because the fatsac is lower than the pump at the rear of the boat.
I plumbed in to the existing pipework when i set it up, it fills great, but hardly empties.

Is there a standard pump available which actually sucks rather than just pumps water once it makes contact with the impeller? I would like to add the fatsacs in the front, but don't really want lots of weight hanging around all the time in the front.

Any ideas?