Larry,

Both Sandy (dawndenise) and KurtV are right about efflorescence (which is why it's so great to have a forum with multiple answers). Your water chemistry is still on the scaling side, but since you don't have cloudy water this isn't something to worry about, though as I said, lowering your TA should help lower your pH rise and acid demand. At any rate, if you make a dilute acid solution using Muriatic acid to clean up the deposits, be sure to remember the rule I learned in chemistry class, "if you're doin' what you oughta, add the acid to the water." The reason is that dilution of acid generates heat so doing it wrong by pouring water into acid can generate enough heat to cause water droplets (with some acid now in it) to boil and splatter (into your face).

Richard