By the way ....Sorry I forgot to add to my post no CYA s of yet. We have very hard well water....900-940ppm and a ton of Iron...water will turm rust for about 3 weeks untill the filter gets it cleared out. I need to rinse the filter a number of times to get the rust out of the water and then planned to add CYA with a sock - I figured I couldn't add it before we got it relativly filtered due to the need to rinse the filters. So for a while we will go through lots of bleach. Thanks again for the help!