SWCG Reduced Efficiency as it Ages?

PoolGate

Gold Supporter
TFP Guide
Jun 7, 2017
4,707
Damascus, MD
My SWCG seems to need to be on a higher percent this year to keep the pool at the same chlorine level as last year (7). I know the pool is clean it is not using any more chlorine, the SWG is just making less. Do SWCGs lose efficiency as they age? This is just the 3rd full year with it running. Beginning of this season the plates were clean. I have never cleaned them the CSI takes care of that. Should I be cleaning them anyway? The first 2 years it was keeping FC at 7 at about 53%. This year I am dialing it in and at 60% it is not keeping up (just checked it was at 5). I bumped it to 65% which I think will be ok. Also I think my CYA is a bit higher this year than usual. Last year I ran it around 60 and this year I got it up to 70 so thinking it should be using less chlorine.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
31,023
Laughlin, NV
I suspect there is a very slight lessening in chlorine generation over time. My SWCG is in its 6th year and I can tell I am needing maybe a touch more % over the same time period versus previous years. Of course environmental differences are also present.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,601
Pleasanton, CA
I have never cleaned them the CSI takes care of that. Should I be cleaning them anyway?
Have you inspected the cell for any scale? I keep my CSI well below 0 and still get scale but I also have pretty high CH levels. The chemical reactions lower the PH near the plates so it is still possible to get scale.
 

PoolGate

Gold Supporter
TFP Guide
Jun 7, 2017
4,707
Damascus, MD
Have you inspected the cell for any scale? I keep my CSI well below 0 and still get scale but I also have pretty high CH levels. The chemical reactions lower the PH near the plates so it is still possible to get scale.
I did just before I opened a couple months ago and it looked great. My CH is always in range or low and CSI is also always in range. I am always adding acid to the pool at least 2 times per week but that is normal.
 

PoolGate

Gold Supporter
TFP Guide
Jun 7, 2017
4,707
Damascus, MD
I shut off the SWG yesterday and added 80lbs of salt. Left it off for close to 24 hours. It lost around 2-3FC during that time. The SWG now shows 3400 salt. I set it at 60% so I'll see tomorrow this time how much it added to the pool. Hopefully it is back where it was. No one swam yesterday and probably won't swim today either.
 

PoolGate

Gold Supporter
TFP Guide
Jun 7, 2017
4,707
Damascus, MD
Cautiously optimistic about the salt addition fixing the "issue". This morning's test showed not only did it maintain proper chlorine levels, it gained around 2 FC in 24 hours at just 60%. It has been colder with less sun lately though. We'll see when summer returns.
 

conphil

Member
Jul 6, 2020
16
The Villages, FL
SWCG Reduced Efficiency as it Ages?
Yes, I've watched my T-15 cell performance degrade over the last 5 years. "Performance percentage" of the cell has been defined as the ratio of instant cell salt reading divided by actual salt concentration. My new cell reported greater than 100% first year (limited data). Then the next 4 years the cell "instant" salinity was always within 100 ppm of externally measured salinity (using salt strips from varying suppliers).... that is about 100% performance most of the time. But during that time I gradually had to bump up the duty cycle from about 25% first year to over 60% fourth year. Then, this year I saw rapid falloff and at 100% run-time the unit did not generate enough chlorine... and I declared end-of-life. (My "performance percentage" was about 80%. Others declare failure at 75%.)
 

JamesW

TFP Expert
Mar 2, 2011
19,768
Note that the performance percentage applies mostly to Aquarite due to the way that the AquaRite determines salinity.

For other SWGs, the performance does degrade the same way, but it's not as easy to determine since they usually use a conductivity test to determine salinity independent of performance.