Vic, I have a Sea Era head, and a Purasan treatment system. I know I have to flush out the Purasan, and suck the water out of the tank. The question is: How do I then winterize the head? Before I installed the Purasan, I would just put the raw water intake hose into the pink stuff and flush it through the head. The manual says not to put any AF into the treatment tank, just suck the water out. Please enlighten me!!