Pool Equipment

Water Balance for SWGs

These water balance tips for SWGs will help you maintain your salt pool with the fewest problems. If you follow them you will probably never need to SLAM (or shock) your pool and you will maintain a more stable pH then if you go outside of these limits. They might not agree exactly with the manufacturer’s recommended levels but they WORK and will help you have a Trouble Free Salt Pool!

First step is to adjust salt to the manufacturer’s recommended range (usually around 3000-3200 ppm but some models do need a higher level. Check your manual.) Starting out slightly higher (200-400 ppm) than the ideal level is recommended, since the salt level will tend to fall over time.

Second adjust CYA to between 70 and 80. The biggest mistake that many SWG owners make is NOT having enough CYA in the water! This can create a lot of problems like high acid demand, algae outbreaks, cloudy water, or early cell failure.

Adjust the SWG percentage setting or run time so your FC level stays between 4-6 ppm. Early evening is the best time to measure the FC level when adjusting the SWG percentage. If the SWG is running at 100% and it still does not maintain a high enough FC level, you need to increase the pump run time.

There are some advantages to running the SWG during the day while the sun is shining on the pool. Unless there is some other reason not to run the pump during the day, like time of day electric rates that are higher during the day, program the pump to run while the sun is shining on the pool.

Adjust your Total Alkalinity to 60-80 ppm. (This is IMPORTANT!)

Adjust your pH to 7.2-7.8 and not any lower. Monitor your pH and when it climbs to 7.8 add acid to lower it back to 7.2 – 7.5 (This is also IMPORTANT!)

Adjust Calcium Hardness to 350 ppm for plaster and fiberglass. Vinyl pools are OK if the CH is at 50 ppm or higher. In any case it should not be much above 400 ppm or you are going to have to keep close watch on your pH to prevent scale buildup. Sometimes your fill water will have high calcium levels so your numbers are higher than recommended. Not really that big an issue if you maintain your pH as recommended above. pH rise is the ONE FACTOR that will predict scaling condition. High pH leads to scaling, period! Keep pH below 8.0!

Finally, optionally adding borates to your water in a 30-50 ppm concentration will help with pH stability with a SWG, particularly when the TA is run in the 60-80 ppm range and pH is kept between 7.6-7.8 but can be useful even if you go out of this range somewhat. There are several borate products on the market–Supreme Plus, Optimizer, Maximizer, Endure, and 20 Mule Team Borax. You can buy the last one at the grocery store in the Laundry Aisle. If you don’t know how to use borates read this article on adding borates or just start a thread asking for info on how to do it. 

To summarize:
FC 4-6 ppm
PH 7.2-8.0
TA 50-90

  • 50-300 for vinyl (Do Not Add)
  • 220-320 for fiberglass
  • 350-450 for plaster

CYA 60-90
Salt 200-400 ppm ABOVE recommended optimum level
Borates 30-50 ppm (optional)