I have a triton II sand filter, and a T10004R system. The pool is roughly 18000 gallons, pebble walled and kidney shaped. I was given no instructions upon given the new house. I do believe the filter is dirty and needs a good cleaning, but i have already seen the pool go from crystal clear to green. I need a bit of help and just think its going to be a shock of chlorine i have to do but would like some pointers on where to start.