What max and min free chlorine would you set on SmarterSpa SWG on Hot Tub???? CYA too???


Well-known member
Jan 26, 2021
I installed a SmarterSpa SWG on my 400 G. hot tub. The Smarter Spa lets you control the max free chorine by adjusting how long it runs AND the minimum free chlorine by adjusting the sensor for when it turns on. What max and min free chlorine would you shoot for as I adjust it?

My tub is most often used by 1 person for 15-30 minutes about 7-10 times per week. It is used by two people for 15-30 minutes one or two times a week. Occasionally it's used by more people. I have used liquid chlorine so I would be willing to supplement occasionally with liquid chlorine and/or add MPS occasionally.

Also, what CYA would you recommend for my hot tub? I use 50 PPM borate. I know for pools the CYA is higher. In the TFP Pool School I learned, "CYA to between 70 and 80. The biggest mistake that many Saltwater Chlorine Generator 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."
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Silver Supporter
Bronze Supporter
TFP Guide
Oct 20, 2017
Southern WI
Pool Size
Liquid Chlorine
FC depends on CYA level. We recommend 30 ppm CYA for covered hot tubs. The high amounts of CYA for pools is because they are exposed to sun.

I’d follow the FC/CUA chart on the liquid chlorine portion. So a minimum FC of 2, target of 4-6. At a minimum you want it to turn on at a FC level no lower than 2, perhaps ideally a bit higher, and run till around 6.

Keep us updated how well it works. I read the owners manual once and it said (or implied) that it would turn on when there was “no chlorine” so I’m specifically curious how well you can dial in the turn-on FC level so I’m giving users here appropriate advice. Thanks!
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