· by Michael Blair, Nashville's Water Filtration
A water softener only works as long as the brine tank makes strong brine. Each time the softener regenerates, it draws salty water from that tank and washes the resin with it, which strips off the calcium and magnesium the resin collected from the hard water. Weak brine means the resin is only partly cleaned, and hard water starts coming through. The two usual reasons are the wrong salt for the tank and a hard crust that forms inside it, and neither one is obvious from a glance at the lid.
Pellets, crystals, rock salt or potassium
Evaporated salt pellets are the purest and leave the least residue behind. Solar salt, sold as crystals, is made by evaporating seawater or brine in the sun and is nearly as clean. Rock salt is mined and cheaper, and it carries more insoluble material that settles as a muddy layer at the bottom of the tank and has to be cleaned out more often. The softener manufacturer’s manual usually names what the unit is designed for.
Potassium chloride is the sodium-free alternative, used by households watching sodium or sending softener discharge onto plants. It costs more per bag, and it regenerates the resin less efficiently than sodium chloride, so the softener’s settings are normally adjusted when switching. Nothing needs to be flushed; the tank is simply run low on one before the other goes in.
The bridge you cannot see
A salt bridge is a hard crust that forms across the tank some way above the water. The salt below dissolves, the salt above fuses into a shelf, and the tank looks full from the top while there is a gap of air underneath. The softener keeps regenerating on schedule, but it is pulling weak brine or plain water, and the resin never fully recharges.
Humidity and temperature swings drive bridging, which is why softeners in garages and utility rooms around Nashville bridge more than the ones inside a conditioned house. Overfilling the tank and using a salt that is prone to caking make it worse.
- Spots and film coming back on glasses and shower doors
- The salt level in the tank never seems to go down
- Soap and shampoo lathering less than they did
- A broom handle pushed down into the salt meets a hard layer
Breaking a bridge and cleaning the tank
A bridge can usually be broken by pushing a broom handle down through the crust in several places, gently, so the tank wall and the brine well inside it are not cracked. Once the pieces drop into the water, the tank makes brine again, and running a manual regeneration brings the resin back sooner than waiting for the next scheduled one.
Mushing is the related problem: salt that recrystallizes into a thick sludge in the bottom of the tank, which blocks the brine from being drawn up. It shows up as a tank with a lot of water sitting over a gray paste. The fix is to let the salt run down, scoop out the sludge, rinse the tank and start again with a cleaner salt. Keeping the tank well short of full, and topping it up more often in smaller amounts, prevents most of both problems.
Softeners in garages as the nights get cold
A lot of softeners in Williamson and Rutherford County subdivisions sit in the garage, next to where the water line enters the house. That space is not heated, and Middle Tennessee usually gets its first frost around late October or early November, with hard freezes to follow in December and January. The control valve, the resin tank and the brine line are all full of water and can crack if they freeze.
Before winter, check that the garage stays above freezing near the unit, insulate the supply and drain lines, and keep the garage door shut on cold nights. A unit that has frozen should not simply be turned back on, because a cracked valve body can leak slowly into the wall or floor for days before anyone notices.