CYA Level for Indoor SWG pool

Feb 11, 2018
Hi, So I know that it is recommended to have a 5-10ppm CYA level (or 20-30ppm for the ease of measurement) in an indoor pool for its ability to buffer chlorine. I also know you have to have a higher CYA level for a SWG system (close to 100ppm) than you would have for a liquid chlorine regiment so that you don't have to run the SWG for as long each day.

So what do we do for indoor SWG pools? Do we still only use a 20-30ppm level of CYA with a SWG and if so, what sort of FC ppm should I be aiming for?

Or if I should maintain the CYA level recommended for SWG of 100ppm, will there be any major consequences of having this high CYA level in an indoor pool?



Bronze Supporter
LifeTime Supporter
TFP Guide
Jun 3, 2015

Does the pool get any exposure to UV (the sun) at all? Skylights in the ceiling etc?

I would maintain a CYA of 30ppm (easy to measure & will buffer the chlorine), and maintain my FC at 8-12% of CYA (3-4ppm), never falling below 6% (2ppm).

Is this a residential or public pool?

The primary reason for higher CYA in outdoor SWG pools is to protect the FC from UV (the sun).
Feb 11, 2018
Hi, and thank you! :)

There are a few skylights but the pool is covered with a motorised pool cover that is completely opaque unless the pool is being used.

This is a residential pool and I would say it is maybe used for an hour a day by a maximum of three people.

But thank you for the recommendations on the CYA and FC levels. I will definitely aim to keep them there!