Does it list the KH. If KH is about equal your water is saturated with calcium and magnesium carbonate. And it might also have a lot of CO2 dissolved water. Try taking a sample of your water in a glass and measure everything you can (GH, KH, PH, TDS if you can ) . And then leave it clown and let it outgas for several day.. Does the same white material develop? If it does you probably calcium and magnesium carbonate rock depositing on your tank walls and other places in the aquarium.
If so you might only be able to resolve this by reducing the hardness of the water by mixing it with RO water to get a reasonable GH. I would also suggest getting a GH and KH test kit.so you can monitor your tank GH.