In general they work fine but are so small (1500 grains per gallon) that they require recharging much too often to suit us full timers. The ones many of us use are 8000 gpg or 10,000 gpg.
Where are parked now in AZ the water has 50 gpg of hardness (that is really hard) and our Mark 8000 has to be recharged every ten days. A Waterstik would have to be recharged every 3 days.
Clay WA5NMR - Ex Snowbird - 1 year, Ex Full timer for 11 years - 2004 Winnebago Sightseer 35N Workhorse chassis. Honda Accord toad.