Free Chlorine Issue : Water Chemistry


New member
Jul 3, 2020

I have a relatively new saltwater pool (11/1/2019) that I can't seem to get back into balance. As a result of allowing my CYA levels to drop to zero, my FC levels quickly followed (Florida sun). In an attempt to get my CYA/FC levels up rapidly, via stabilized chlorine tablets & Stabilizer pouches, I accidentally allowed my CYA levels to climb into the 130 ppm range. I then proceeded to partially drain the pool. My CYA level is now back down to 60; however, my salt water chlorine generator can't seem to keep up with my minimum FC requirement (60 - 7.5% = 4.5); thus, I've been adding about a gallon of liquid chlorine per week; it appears the FC would drop to zero if I didn't intervene. We do actively use our pool 6 times a week. We also have a toddler that most certainly introduces both #1 & #2 into the water regularly. Should my SWG (80% ) be able to keep up with this FC demand? Is it possible that I may need to SLAM? If so, what FC level would be desired?

Test Results:
  • Test Date: 7/3/2020
  • CYA: 55-60
  • FC: 2.5
  • CC: 0.5
  • PH: 7.6
  • TA: 80
  • CH: 330
  • SWG: 80% output
  • Cartridge: 250 SQFT
  • Cartridge Date: 6/27/2020

Salt levels are Good. The SWG cells were acid/water washed about a month ago (almost no build-up was identified). The pool has always looked clear with excellent visibility. Wondering if the SWG & Liquid Chlorine are producing just enough to mask a more serious underlying containment issue?

Your help would be greatly appreciated.
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Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
Franklin, NC
While you say you have a Pentair Intellichlor, you don't say what size. The size plus how long you run it and the % you run it at will determine the amount of chlorine being produced.

To determine if you have a hidden issue, conduct an OCLT



New member
Jul 3, 2020
Pentair Intellichlor Model: IC40
Run Time: 8 hours per day @ 80% output

Just remembered that due to the addition of the Pool Heat Pump, I had to cap the flow rate limits on the pump @ both the low and high end (Intelliflow VS).
Min GPM: 30
Max GPM: 80
Running Speed: 2300 RPM (749 Watts)

I will certainly conduct the OCLT tonight; however, if somebody could, in the mean-time, comment on my new proposed schedule (see my signature below).
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