I would check the calcium level in the water - if you are pouring in a lot of cal hypo, and your calcium is high you will get some calcium precipitating out of the water. Therefore I would use just plain laundry bleach. You must take it up to shock which will be 10 ppm without any cya in your water, which would be 4 1/2 gal of 6% bleach. You have to test often and add enough to get your level back to 10 - the more consistant you are, the faster your water will clear. You can also vacuum to waste - this will get out a bunch of the gook before it hits the filter - plus you will be adding back nice clean water. Brush the sides - skim off as much as you can of the gunk, and bleach, bleach, bleach!! Good luck, you will be very happy you did it!