I have an older (2002) FG in ground pool that is surface coated with a white coating of some sort. The pool constantly clouds up after a robotic vacuum or brushing and the white matter generated is not filtered out by the filters. It stays that way for days and I can not see the pool drain which is at about 6' in depth. When I rub my hand along the side of the pool surface coating I release a white cloud of material and it is too small to be filtered out. Apparently the coating is "chalking". Is there anything that can be done to prevent this problem short of resurfacing the 10,000 gallon pool. ? Someone mentioned low calcium as a possible cause.