Keeping Free Chlorine stable


New member
Apr 23, 2021
Hello everyone,

I got a Atlas Spas Balance 8 back in December and I'm still not 100% confident in keeping my Free Chlorine correct. I was told originally that my Free Chlorine and Total Chlorine don't matter as long as I use my chemicals regularly. I know now that I was told incorrect. Our TDS were high so we just emptied and refilled our hot tub (450 gallons). I got a floater to use chlorine tabs. I'm using 1 inch tabs in there right now. I've put in three tabs and my free chlorine has been staying about 3-4 ppm with the floater opened about 1/2 way. Here is my challenge.....can I just keep using the tabs to keep the chlorine at a good level or should I still use my chlorine powder once a week with my shock?

I hope I'm making sense.


Active member
Jan 9, 2021
Pool Size
Liquid Chlorine
The problem with dichlor and trichlor tabs and powder is that they quickly add to your CYA (cyanuric acid) level. The higher the CYA, the less effective free chlorine is. The general consensus for residential spas is to have your CYA between 20 and 40ppm. You will quickly exceed that 40ppm when using dichlor or trichlor, whether in tablet or granular aka powder form. The more dichlor or trichlor you use, the more you need next time to achieve the same sanitizing effect due to ever-increasing amounts of CYA blunting the effect of chlorine. Also, the manual for Bullfrog spas says warranty is void if you use trichlor (due to being very acidic aka very low pH).

For those reasons, the dichlor/bleach method advocated on pool/spa forums means to use just enough dichlor to reach 20-40ppm CYA, and then switch to straight pool chlorine aka bleach, which does not contain any CYA. Any CYA you've added from the dichlor effectively stays there until you drain the spa, so you need just enough CYA to mildly blunt the effects of chlorine so that it doesnt bleach your swimwear and your skin, but not so much blunting that it decreases sanitization ability.
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