Considering a second SWG


Gold Supporter
Aug 3, 2018
Leesburg, VA
Hi, TFP Family!

It looks like my current SWG isn’t sufficient to keep our pool at the right chlorine levels during the sunniest days of summer. After adding bleach to hit 5ppm last night, we’ve ended the day with 1ppm of free chlorine. (This is with my poor Jandy AquaPure 1400 SWG working overtime, running 18 hours per day at 90%.)

I’m pretty sure this is because the original owner didn’t follow the TFP rule of thumb: install SWG capacity sufficient for 2x your pool volume. Our pool is 30k gallons and it looks like we need more capacity.

Could the resident experts please confirm that I’m thinking through this the right way? And is there anything I should request when I talk to my builder about installing a second SWG?

Here are my numbers just now (using my Taylor test kit and K-1766 salt test):
  • FC: 1.0
  • CC: 0
  • pH: 7.6
  • TA: 70
  • CH: 480
  • CYA: 90 (just added a bunch this week)
  • Salt: 3800
  • Temperature: 81 degrees
  • Note: we have a southern exposure—all sun, all day
Thanks, as always, for your advice!


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

Your cell should generate .233 ppm of chlorine per hour, when run at 100% and 24/7.. or 5.6 ppm per day

At 18 hours and 90% that should be 3.78 ppm per day..

Running your current cell harder and longer until it dies should work.

Then replacing it with a 60K SWCG makes sense.

Your CYA level makes a lot of difference in the amount of FC loss.

With an FC of 1, it would not "shock" me to find that you already have an algae bloom..


Jim R.
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Gold Supporter
TFP Guide
Jun 7, 2017
Damascus, MD
Pool Size
Salt Water Generator
SWG Type
Jandy Aquapure 1400
I have the same size pool as you and basically the same SWG and running mine at 53% gets me about what I need to maintain FC of 7. How old is the cell and has it always struggled to keep up?
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