I followed the advice to clean up a REALLY green pool, although I had to use the dilution method of checking my chlorine level. I also had to drain the pool around 2/3s to get the CYA level low enough to make the chlorine work. It still took a huge amount of chlorine and several weeks, but the chl level finallly stabilized and the algae is gone. However, even after running the filter 24/7 the pool is still cloudy, as in can't see the bottom in at the shallow end. I have cleaned the Hayward cartridge filter maybe 4-5 times since begining the great algae kill off. I recently tried shutting the filter off entirely and letting the dead algae settle to the bottoom and vacuuming it up. As I was vacuuming, I could see a fine whitish powder blowing out the return. The filter is picking up some of the stuff- I took a close look at it and cleaned it yet again yesterday. The white stuff is evident in the folds of the filter material, but obviuosly it is not picking up all of it. I have also examined the filter carefully for tears in the fabric of the cartridges- none evident. I have also on 3 occasions tried Pooltime Water Clarifier, with no success. I there any product that will clump the dead algae so my filter will pick it up? Thanks again to Chemgeek for his advice and directing me to this site!