An aquatec 8800 will easily self prime through a 5 micron filter. When it doesn't you'll know it needs to be changed.

The 125psi really isn't a problem on the filter. Unless it is entirely plugged the filter is actually seeing very little pressure differential (125 in and 125 out). They can handle a 80psi pressure differential, and if you had that you wouldn't have enough pressure to produce any permeate so you would have replaced it long ago.

The filters are wound to have inlet pressure, not suction. As they get plugged they squeeze tighter to decrease the probability of particles getting through. If you suck through them they probably wouldn't perform the same and you could lose your 5 micron absolute filtering capabilities. Plugged filters collapse under suction but hold their shape under pressure.