A use for your old SWG Cell

smallpooldad

Well-known member
Aug 6, 2008
429
Honolulu
Most of us do not have the luxury of bypassing our SWG cell when shocking the pool with chlorine, especially at high levels.

I believe most manufacturers recommend that one does not operate the SWG cell with high levels of chlorine as it can damage the cell, or shorten its life. If then when you replace your cell you keep the old one it can be used when doing any kind of shock treatment with liquid chlorine, saving your new or current cell.

If someone already wrote on this please excuse me, but I thought it might be useful.
 

smallpooldad

Well-known member
Aug 6, 2008
429
Honolulu
bk406,

"Excessively high chlorine levels can cause premature cell failure and corrosion
damage to pool fixtures and equipment"

Pool Pilot Digital Manual, page 24

Aloha.
 

smallpooldad

Well-known member
Aug 6, 2008
429
Honolulu
bk406,

Recently, shocked for nearly a week recently but that was due to unusual demand.

Do not shock very often otherwise, but for those that have an excess algae problem it could be useful if they shock for more than a few days.

I would imagine that Pool Pilot and maybe others have their reasons for making this statement.

Anyway it cannot hurt, and as they say better safe than sorry, and it costs nothing, unless you get a credit on your old unit.

Aloha
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
It makes absolutely no sense that high chlorine levels would shorten cell life. Saltwater chlorine generators GENERATE extremely high levels of chlorine that then dissolves in water to drop the pH significantly so the active chlorine level near the chlorine generation plate is extremely high. The plates have to have coatings that resist corrosion from such very high chlorine levels. Manufacturers have stated that between the plates the chlorine level has been measured at 80 ppm FC so would be even higher very close to the chlorine generation plate.

Also remember that even the shock level recommended on this forum where the FC is around 40% of the CYA level is equivalent to only around 0.6 ppm FC with no CYA. Because of CYA in the water, the active chlorine level never gets very high. Even at high shock levels, it is almost always lower than typical indoor pools at 1-2 ppm FC that have no CYA. At yellow/mustard algae shock levels with an FC that is 60% of the CYA level, this is equivalent to around 1.4 ppm FC with no CYA.

(I edited this post and added the following as Jason wrote his post -- we're saying the same thing)

As for the Pool Pilot manual quote, they are referring to the fact that getting to very high chlorine levels means your SWG on-time is too high and of course that reduces its life. They are also referring to the fact that if the active chlorine levels gets very high that this can accelerate metal corrosion, but that is much more likely in a pool with no CYA such as many indoor pools where a runaway SWG could raise the FC to well above 5 or 10 ppm FC with no CYA which would be more harmful to pool equipment in the long-run -- some pools that aren't monitored get to 20 ppm FC or more. Again, with CYA in the pools we have far less likelihood of having problems, plus pool owners test their chlorine levels to make sure that the SWG doesn't run without adult supervision, so to speak.
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
I can imagine a situation in an indoor pool, should the FC level got into the 30s and CYA was zero, that could cause various kinds of damage. In an outdoor pool with CYA in the water, it doesn't seem plausible that there could ever be a problem.
 

smallpooldad

Well-known member
Aug 6, 2008
429
Honolulu
Maybe the representative from Pool Pilot, Poosean - Sean Assam is his name I believe, could illuminate us on what parameters Pool Pilot are using to issue this warning.

Although everything you both wrote makes sense, especially the part about 80 ppm.

Thank you.
 
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