I had PVC pipe installed from skimmer to pump last year, and there is no disconnect from the skimmer box side (so pipe is detatched from pump only). Water pooled in the box during the winter, and now the water that is still in there is a bit green, and it's dirty. Should I blow that water out with a shop vac, and scrub the box before connecting everything and opening? (I can't see inside pipe or clean it though). Or do i just leave it and pour lots of chlorine in?