One more thing to check.Test the water comming out of your RO/DI,my town adds so much damn phosphates I had to add another DI canister to the system.I think people assume just because they have a RO/DI the water is good.I test for phosphates,nitrates,silicates.I have 2 RO/DI's in my house one for the tank and one for drinking water.I added spectrapure DI's to both systems..HTH too