So, I had to buy a new membrane for this season because my old membrane was flowing at 64%. Now I have an extra membrane.

I use well water for pre-season rinse. Never known there to be mineral/sediment issue with it (the whole house filter on the well doesn't plug up). Is there any merit to putting my old membrane in first, concentrating say 400 gal of well water to generate 300 gal of permeate. Put the new membrane in and do a pre-season rinse with the newly generated permeate water. It probably takes me about 30 min to swap the membrane out. Wasn't sure if I gained anything by it.

Thanks for the input.