I have been using a copper/silver ionizer for 10 years and have the cleanest most chemical free pool here in France! However, I recently changed from sand filtration to a clean and clear hayward cartridge filter of a size suitable for my 25,000 gallon pool in order to save water from backwashing, and it is gunked up every three to four weeks. I am wondering whether the copper/silver ions are doing this and whether I should go back to sand? The pool gets heavy usage in season as it is at a holiday rental property so do I need a larger cartridge unit? My pump is a hayward 1cv energy efficient model. Labour maintenance here is costly. I would rather cut my losses and get the right system as it will be more cost effective in the long run. Any help would be much appreciated.