I could use a little help! Im pretty sure my filter is needn to be cleaned in the worse way. So I bought some Filter Renu and not real sure how much of this I should add. From reading directions it says to add. 1lb per 5 gallons of water that the filter holds. My dilema is Im not sure how much water the filter holds. I do know that it holds 250lbs of sand. I did the calculations like they explained and Im not sure if I did them quite right.What I came up with was that the filter probably holds 120 gallons of water.Does that sound about right? That would mean app. 20lbs or so of the filter Renu is needed. That just sounds like an awful lot to me.Perhaps just adding new sand would be better solution??? Reason for doing this is cloudy water with proper readings that will not clear up. It was very green and nasty at beginning.Pool sat without using last year. We were able to clear up the green to see to start some vacuuming thats when it turned cloudy and unable to see to vacuum at all now. Please Help!