SWG reading vs Taylor salt water test an tips on how to dial it in


Bronze Supporter
Oct 14, 2017
Richmond, TX
Ladies & Gents,

Would appreciate your guidance or affirmation that I'm on the right path.

Brief history, PB added salt a day earlier than originally planned and I was not there to witness, but was told that 7 bags of salt were added to our 15k gallon pool. SWG is a Hayward T-15 cell. They immediately turned brought the cell online after adding salt, vs waiting 24 hours or so to let salt dissolve.

Pool temp is in the 70s and the SWG reads salt levels in the 3200 to 3300 ppm range, which is in it's perfectly happy zone. Meanwhile, using the Taylor kit I get a reading of 4000 ppm. I certainly didn't expect the cell reading to be as accurate as the reagent test, but the 800 ppm difference surprised me. The water feels perfectly fine, so no concerns from a pool enjoyment perspective, but not sure if the big discrepancy is something I need to worry about for the health of the cell sake.

In addition, PB originally put cell output to close to 90%, resulting in a fairly drastic spike in FC (from 5 to 12) in the two days before I had an opportunity to test everything. Since then I have dialed the SWG down to 10% (didn't want to fully turn off after just coming online) and FC level yesterday was down to 5.5. My CYA level is currently at 40 and I know I need to raise now that the SWG is online, but did not want to do so while the FC levels were high, as I assume it would have slowed FC coming down.

So my plan is to let FC come down to 4 and then increase SWG output incrementally until I have a good sense of daily FC creation, and at the same time increase CYA to about 70. Does that sound like the right approach?

For full transparency, below are the complete results from last nights testing:

FC 5.5
pH 7.8
TA 70
CH 225
CYA 40
Salt 4000



TFP Expert
Mar 2, 2011
(7) 40 lb bags in 15,000 gallons increases the salinity by about 2230 ppm. So, something is off.

Try brushing the pool really well and redo both tests.