Translating SWG% to ppm?

Steve-D

Bronze Supporter
Jul 10, 2020
161
SW Boston Suburbs
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Could someone please check my math/assumptions estimating the daily addition of FC in ppm based on the % setting on my IC40 SWG ? It is a new pool (plaster) running since May and I haven't yet worked out the optimal SWG setting where I can (mostly) just set it and forget it. We have a heat wave coming this week and I don't want to get behind what will likely be an increase in daily FC lost.

What I've calculated for a 20,000 gallon pool using info I've gleaned across various posts here is that our IC40 Chlorine output is rated at 1.4 lbs @ when running 24x7 @ 100% which roughly translates to 4.0 ppm at 50% with each 5% increment representing about 0.4 ppm. Am I doing this right?

I have about 1.5 gallons of liquid Chlorine (12.5%) on hand dated late April 2022 I can use for a quick FC boost if needed but I'd like to try and get away from daily tinkering with the SWG % to the extent that I can. For my CYA level my "ideal" FC target is 5.0 so I'd like to aim for a steady FC level closer to 6.
 
Last edited:
Thank you for the quick reply, Marty.
I also just edited my post to correct some cut and paste errors plus some grammar changes for clarity.
You folks are the best!
 
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