I had a recent issue with the Spider gasket, that's fixed now. I know it was blowing sand into the pool, and when I drained the pool there was quite a bit scooped out. SO, I think I need sand, and that is why my filter is not "filtering" as well as it should. The book says 225 lbs of sand, but I have no idea how many lbs are in there...so is there a level of sand I am trying to achieve? Like halfway, or 3/4 of the way up the filter? It is a top mount btw. Hayward s220. I figure while I am digging around in there I might as well check the laterals and change them also if needed.