cya levels

[aussieta]

just curious why a salt pool has a different recommended fc/cya level to a non salt pool
i cant see the difference between adding bleach at night or SWG
both pools would add the same fc ppm, both same sunlight, bather load etc
is there some chemical relationship i dont understand
please keep it in laymans terms, i haven't studied chemistry since high school 35 years ago

 

[JohnT]

SWCG manufacturers usually recommend those levels to maximize cell life.

Group experience tells us that SWCG users don't experience CYA related problems the way others do. It is probable that the reason is that as the water passes through the cell, it is exposed to very high chlorine levels. In effect, you are shocking the pool every day a little at a time.

 

[jblizzle]

The SWG generates the FC very slowly, unlike bleach where you can add 2-3ppm in a matter of minutes. The higher CYA is meant to protect the FC a little more from the sun so the SWG can keep up. Also, because the FC is better protected, the SWG does not have to generate as much FC each day.

The risk of the higher CYA level is if you have the SLAM, the required FC levels are much higher than at lower CYA levels.

The recommended FC levels are lower than bleach for the same CYA level for a few reasons, the SWG does not have a human in the loop to forget to add bleach, and the environment in the SWG cell is harsh which helps prevent algae. The recommended minimum levels for SWG are the real deal, do not go below this number while the minimum for the non-SWG may have a little wiggle room.