Hi. We got a brand new Hayward 1HP pump and filter last July. This year when we opened the pool it was a little green but clear to see to bottom. Pool is 21k gallons 16 X 32 rectangular inground with 3 ft and 8 ft ends. After 8 days of endless work and endless BAC products we gave up and started the conversion to chlorine using the bleach method. I have noticed that my filter since the beginning has been running at 20bpi and unless I vaccuum on waste and THEN backwash I can't ever get my pressure under 10. Once I finish backwashing and rinsing the pressure goes back up to 20 and I backwash it when it gets to 22. Do you think this is normal? Could the bacquacil have damaged the filter in any way? It is under warrantee until mid July 2011. Any thoughts on this subject are quite welcome. Conversion coming along nicely. Low end is clear and sparkly, algae is dying and am brushing away the brown dead stuff. No longer live green algae. Thanks!