I have several dozen trumpet and ramshorn snails in my 30 gallon tank. When I started this tank they were a mixture of beautiful golden browns. Now they are white, like calcium white. I have very hard water, more so than what my test kit could measure. I also have driftwood in the tank. No algae whatsoever, they only eat whatever the fish don't get. Anyway, do you think there is any hope of getting my snails' shells brown again? Any recommendations?