What does pool stabilizer do?

It holds on to chlorine loosely and protects it from sunlight, which otherwise breaks unprotected chlorine down within hours. That is why it is called stabilizer or conditioner. Without it, an uncovered pool in Florida would burn through chlorine nearly as fast as you could add it.

About 30 to 50 ppm for most chlorine pools, which is the range in our pool chemical levels guide. Salt systems often ask for more: Hayward's AquaRite manual lists 60 to 80 ppm for its salt cells. Whatever the level, the CDC says a pool using stabilizer needs free chlorine of at least 2 ppm rather than 1.

The chlorine gets slow. The more stabilizer in the water, the more of the chlorine it holds in reserve, and the less is free to kill algae at any given moment. The pool tests fine and turns cloudy or green anyway, and shocks seem to do less than they should. People call it chlorine lock. The chlorine is not gone, it is just held back.

Chlorine tablets and stabilized granular shocks (trichlor and dichlor) add cyanuric acid every time you use them, and nothing in the pool breaks it down. Only water leaving the pool takes it out, through rain overflow, backwashing or splash. In a pool that runs on tablets all season, the level keeps climbing. If you would rather not keep track of it, our weekly pool service checks and corrects the water every week, with every chemical in the price.

Replace some of the water. Draining part of the pool and refilling with fresh water lowers the level in proportion, so replacing a quarter of the water lowers it by about a quarter. Products sold to reduce it are hit and miss; draining and refilling is the method that works every time. Do not drain a Florida pool all the way without knowing the water table. Should I drain my pool explains why.

Add stabilizer, dosed for your gallons by its label. It dissolves slowly, so add it the way the label says and give it a few days before you test again, or you will add too much chasing a reading that has not caught up yet.

Yes. The salt cell makes chlorine, and that chlorine burns off in the sun like any other. Salt and stabilizer also drop together as water is replaced, which is why Hayward says to check stabilizer whenever you check salt. More on salt pools in salt water vs chlorine.