2 yrs this December we had a Simple Soft Plus , Water Softener installed.. Just ahead of the Softener is a UV Light as well... Reason being we were having Issues with Hard Water and lingering Rust Stains that can be very unsightly in the best of times.. Anyway after having the Softener installed the Rust Stains vanished... Now after coming home from being 10 days away the Wife had plans to soak in a Hot Bath ,once she was in and moving the Suds around she noticed the water looking kind of Blackish... Upon draining the tub the sides were stained a dark color.. The only recent addition was Replacing the Hot Water tank beginning of Summer.. But this is the 1st setback since installing the Water Softener.. Any ideas where the problem lies.. Thanks

If you have rust stains, you probably have iron bacteria in your well. This manifests itself as black "yuk" that sometimes comes with a musty or sulfur smell. Theoretically, the UV can disinfect it, but it takes longer than the time each molecule of water has going through the pipe. If it's not too plentiful, the softener can filter it out, but it will quickly clog up the filter medium in the tank... I'm talking about a year or two. The fact that you say your softener is two years old, combined with the water being stagnant for 10 days, plus the nice growing conditions in the hot water tank, could produce the black stains you're referring to.

The standard treatment for iron bacteria is a chlorine shock to the well. Unfortunately, it's usually a temporary solution and has to be done periodically, maybe every year or three. Instead of the UV, or in addition to it, you might want to check into a whole-house filter (either the cartridge-type requiring lots of attention, or the self-flushing type like Sears has). Otherwise, you may need to periodically replace the filter medium in your softener. It can be done by the homeowner if you're handy, by removing the top of the softener and using a wet vac to suck out the beads. Then just pour new in, usually a cubic foot of it.

I think the "black stuff" on the inside of your tub is related to not using water for 10 days. See if that happens one week after continuous use of the house.

Back to you. Milo