SWCG Questions.

Feb 4, 2017
So Cal
So I am new to this whole pool thing. Our pool just got finished about a month and a half ago and we added salt to the water last weekend. Prior to adding salt I was able to get the levels of everything in good ranges. After adding the salt the PB turned on the SWCG and now my fc is at 21.5. I turned off the SWCG and hoping the fc will fall this week and get back to about 5. My cya level is about 80-90 and my salt level per the SWCG is at 4100. What I'm not understanding is how to get the SWCG right so that it keeps the chlorine at 5. The SWCG was at 75% which is what I believe the PB set it at. My pump was at 100% from 7:15-4:15 and then 50% from 7:15 to 10:15. I recently turned the second speed off. Any help with the SWCG would help me. I hope I explained myself ok. :D:confused:


LifeTime Supporter
TFP Guide
Jan 18, 2015
Bunbury, WA, Australia
With a SWG you can adjust the amount of FC that it makes by either adjusting the pump run time or the time the SWG is actually on (percentage time). You'll find that it will take some trial and error to get it to a point where it can more or less maintain the FC level you target. You would ideally test daily for FC to track how it is holding up but you will find that it will come down fairly fast from the higher level.

The changing seasons also impact on a higher FC demand as things warm up again- so it is good to ensure you stay above your targeted FC for your CYA. If you are running at 90 CYA then want to make sure you never go below 5 FC as a minimum see Chlorine/CYA chart.

You also seem to be running your SWG for a long time which would probably explain the high FC levels. You could wind your SWG back to 8 hours run time and work back from there.


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

Ok, so the SWCG produces chlorine based upon two things.. One is the % of output, and the other is pump run time. The way you control your FC is to adjust either or both of them.

One hour of pump time at 100% SWCG output, is the same as 10 hours of pump run time with only 10% SWCG output. Whatever works for you is ok...

In my case, I believe that it is better to produce a little chlorine over a longer period of time, so I run my pump a lot and keep the % of output low.

Each pool is a little different, but for sure 75% output with the pump running 24/7 is way too much for this time of year.

SWCG's do not know how much chlorine is in the water, they only do what you tell them to do, and YOU are the feedback that closes the loop. So, you still need to test and then make adjusts to move your FC up or down.

As the summer gets here you will have to keep increasing the output to keep up with the sunshine, and the opposite will be true in the winter.

Thanks for posting,

Jim R.