aluminum chloride exists in a stable form when dry. if contacted by water it burns. the deposits in your tank are probably some sort of solid white hard aluminum oxide crystals.
removing chlorine from your water will have no effect on the formation of these crystals. take the chlorine out if you don't like the taste of it.
with a 10 year old IP that has a spectra watermaker and having never taken on municipal water(chlorine destroys the membrane and is totaly avoided and never introduced) - there are still crystals.
the advice to add a pre-pump filter solves the problem. the few drops of chlorine (4 drops of chlorine for every million drops of water) in your local water will not harm your tanks.
The EPA regulates chlorine in the drinking water of all communities, adding a nationwide level of oversight. Chlorine and chloramine levels are capped at 4 parts per million. By the time the water gets from the treatment plant to your faucet, levels are probably down to 2 ppm.
Last edited by phaiakian; 11-02-2008 at 10:02 AM.