SWG showing 3000 but tests showing 6000 - 4 yr old T-15 cell

philipaby

Bronze Supporter
Feb 5, 2020
13
Katy TX
Folks,
This problem has been ongoing for a couple of months now. Salt levels for the pool started dropping to 2400 and as expected had put in 3 salt bags. The reading barely crept upto 2700 and then I noticed that the reading would drop 100 ppm by the day. At that point we had heavy rain and so I figured would add more salt on account of overflow etc. Now added 3 more bags. And the salt reading went upto 2500. This seemed kind of odd. And then added 3 more bags after and the level went upto 2600. At this point the pool tech did his own test and showed 6000 ppm. Water also tasted a lot more salty. He cleaned the salt cell which seemed to be dirty and after that the ppm on the display went to 3000. I checked the voltage, amps on the aquarite at that point and it was 24.8 and amps was 2.7. Today morning I did a re-calibrate and the reading settled at 3200. Did a run through the readings and got 89 as temp, 26 as voltage, 6.7 as amps and cycled through the rest until the t-15 and so on.
The cell was replaced in May 2016. Has anyone seen or been through similar situations? Does this smell like a cell gone bad? I also did salt testing myself with aquacheck strips and they still show 6000.

Thanks in advance.
 

philipaby

Bronze Supporter
Feb 5, 2020
13
Katy TX
@JamesW, bad cell seemed to be the approach because two different kinds of tests are giving up the same number while the only thing showing a drastic difference was the aquarite display. I'm not sure I understood your response on aquarite showing the temperature on the display. That came out as 89 which matches what it was at the time.
 

JamesW

TFP Expert
Mar 2, 2011
22,029
Check the diagnostic readings and then switch the cell off for a minute and then back on and recheck the readings. The amps and instant salinity should be the same.
 

conphil

Member
Jul 6, 2020
16
The Villages, FL
My recent experience with a failing T-cell-15 sounds somewhat similar to yours. When the display reading for salt level started going down (similar numbers like yours), my service tech (a manager, no less) simply added salt. FYI, the Hayward manual says says that given a low salt display... initially NEVER add salt .... first you should do a cell cleaning, and then a "actual" (external) salinity test. When I pointed this out, they finally did the acid wash of the cell (there was calcium in it). Then they measured salinity and determined that they had added too much salt. But the T-cell now read a slightly higher level (still much lower than actual)... but artificially high enough that the unit would run and produce some chlorine. We limped along for a couple weeks running the cell at 100% (more than double where it ran for 5 years) until it could no longer produce enough chlorine and we declared the cell was end-of-life.

In your case of a 4-year-old cell... it might be failing depending on how hard it has been run. I don't understand what drove your amps from 2.7 to 6.7. Was that before and after you added salt? Typically the amps go up as salinity increases. I my case I was always running above 7 amps... even when the unit displayed low salt (but it wasn't really low).

Lesson learned (for me, at least).... do not depend on the display level if you want to know the real salinity. As others have pointed out... measure it externally before adding salt.
 

mguzzy

Gold Supporter
Jul 8, 2015
2,533
OV, CA
That sounds like a typical story of a failing SWG. At some point you wont be able to add enough salt to keep it happy and the high salinity will start causing issues with the controller. They lifespan of an SWG is also dictated by its environment. I see you are in TX. How warm is your water? what % do you typically run it at. Do you have a long swim season.. all factor into it.
Follow JamesW he knows the diags you can do on your cell to check it while its still insitu.
 

philipaby

Bronze Supporter
Feb 5, 2020
13
Katy TX
Thank you all for your responses. @conphil, that is interesting you had a similar situation as mine. I could be headed down that same path. @mguzzy, water temp is at 92 right now and I run the SWG at 70% typically. And yes, swim season in TX can be for a while since our summers in Houston are long. But there is not a lot of water heading down the drain since the level of the pool is not that close to overflow.

@JamesW, thanks once again for your input which has been very valuable. Pool tech literally came by an hour ago and I relayed all the feedback here. He did a test again and sure enough was 6000 ppm. So we tried to look at the diagnostics again and lo and behold, the amp was at 0.0. Which also as I've read, is a sign of a bad cell. At this point, the tech has not added any chlorine or anything to modify the chemistry since he wants to make sure there's no other variable and if it looks the same next week when he comes (I think it will remain the same), then will replace the cell. I guess, when that happens, then the new cell might likely say High salt because of the 6000, at which point, will have to dump in a bunch of fresh water to the pool. If I'm assuming wrong, please let me know. Appreciate all the help!
 

JamesW

TFP Expert
Mar 2, 2011
22,029
The amps go to zero periodically based on the percentage.

For example, at 50%, the amps will be good for 90 minutes and then 0 for 90 minutes. The cycle time is 180 minutes. The generating light stays on the entire time even when not actually generating.

Move the switch to off and then back to auto to start a new cycle and check the amps and instant salinity.

Then, move the switch to off again and back to auto, which reverses polarity and then recheck the readings.
 
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philipaby

Bronze Supporter
Feb 5, 2020
13
Katy TX
@JamesW, so glad you suggested to check with those steps cause I do see some weird readings that might make total sense to you :) Wow, even your points on amps being 0 for 90 mins and otherwise for the other 90 mins, am not sure I would get that information in any manual, thank you :)

In any case, I did the switch off and back to auto and the readings were as follows (voltage, amps, instant salinity) - 27.2, 2.92 and 700
When I switched off and then back to auto again the readings were as follows (voltage, amps, instant salinity) - 25.4, 6.44 and 2900

The average reading was at 3000 ppm as usual.

Really scratching my head at this point, as not sure what to make of this.
 

Scott3721

New member
Jul 16, 2020
2
Pembroke Ma
i'm sure by now you have figured everything out. but if not consider this, something i've learned because of my own salt level reading problems. my salt level would crash overnight by 1000 points or more but climb back during the day. figured it was circuit board. but a hayward tech just got back to me and said it could be a flow switch problem. if flow switch gets stuck in the on position when the pump is off it continues to energize the cell, but because there is no water flow there is no salt to read. so salt level goes down. pump comes on in AM and starts to read salt level accurately recovering to real number eventually. hard not to throw some salt in when its reading low. i'm hoping that's all it is, but the answer he gave makes perfect sense.
 
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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
34,629
Laughlin, NV
if flow switch gets stuck in the on position when the pump is off it continues to energize the cell, but because there is no water flow
Welcome to the forum!
The SWCG should have power removed from it when the pump is not running. The condition you state above can lead to the SWCG exploding. Please change this condition immediately.
I suggest you read ABC's of Pool Water Chemistry.
 
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philipaby

Bronze Supporter
Feb 5, 2020
13
Katy TX
@JamesW, figured I'd just report back to the group on something interesting. Per your instructions, I'm adding fresh water to the pool to reduce the salinity level to the mid-3000s. Last I posted, the actual ppm per the Taylor kit was 6000 ppm. And the aquarite display showed 3000. Over the past 2-3 days I added in approx 6000 gallons of water and the kit read the ppm at 5000, which is fair. Interestingly, the aquarite display is now at 2400, so it's like it is showing decrease as well even though it's not the right decrease :). Just out of curiousity, the voltage was 28 and the amps was 2.14 and then I reversed polarity as before and now the voltage went to to 26.7 and amps at 5.17. Assuming that even though the cell is faulty, it still is able to sense the decline in salt, right?
 

conphil

Member
Jul 6, 2020
16
The Villages, FL
Assuming that even though the cell is faulty, it still is able to sense the decline in salt, right?
Yes, I observed a similar decline (high salinity subsequently diluted to desired salinity) when my T-cell-15 was failing.... but smaller numbers than yours. The display always read about 500ppm lower than actual. When my salt was too high, the cell seemed to function... that is I could tell chlorine gas (bubbles, I guess, of chlorine and hydrogen) was entering the pool.


I'm curious... do you see evidence of chlorine production?


BTW, as I've written in another blog, my NEW T-cell-940 continues to read about 300ppm HIGHER than actual. I suspect this ratio just goes down as a cell ages. When you get a new cell, will you please report this ratio of display value to actual salinity? Again, I'm curious.... to see if others report display values higher than actual when a cell is new.
 

mguzzy

Gold Supporter
Jul 8, 2015
2,533
OV, CA
The T-Cell's do not have a separate salinity sensor. They calculate the Salinity from the voltage and current that is applied to the cell. So if the electrical characteristics of the cell change due to the age or a malfunction, then you will see it in erratic Salinity readings. ... just sayin'