JANDY Intermittent Code 121

George Whitzel

Well-known member
Jul 23, 2017
247
San jose, california
Pool Size
17000
Surface
Plaster
Chlorine
Salt Water Generator
Need some help and advice. I have a Jandy Aquapure 1400 SWG. I need some advice on a potential problem with the system. Initially after system turn on I get a no flow indicator displayed. The power light on display is lit but no cell lights are on. After a while I get either a cell reversing or cell on flow illumination and a flow display. Today after system turn-on both the Cell-On and Cell-Reversing lights are on. Intermittently I am seeing a error Code 121. A chemical test shows a FC reading of 3 and the pool is clear so I am assuming that the cell is producing chlorine as I have not added chlorine to the pool. I very recently replaced the flow sensor. Can someone advise to what might be going on?
 
You need to keep your threads together, it will help us to see the whole picture.

I'm 99% certain the cell needs to be replaced. Earlier you had error code 120 and now 121 which means the cell is very close to being 100% dead. Look very closely at the plates and you will most likely see some wear on the plates.
 
I remove the Cell for cleaning and inspection today. The plates did not look to bad but when I acid washed the Cell some small white piece come out of the Cell. Not sure what they are. I think you are right that the cell is probably going bad and needs replaced. This will be the third cell replacement in the 9 years I had the system as well as the replacement of 3 bad sensors. I need to find a more reliable replacement SWG Any recommendations?
 
Later today I reread the instructions that came with the new Sensor and noticed a section about calibration of it and performed the procedure. This resulted in the no-flow indication changing to flow and the Cell On light coming on and staying on for the entire 2 hours remaining in the programmed on time. Not sure if fixed the problem or not but I will keep a close eye on it the next few days and report back.
 
Today I had some symptoms return. After system turn-on and wait period the Cell on light lit as well as the Cell Revising, Flow and Service light. No codes were being displayed. Also the witten display said Chlorine Production and Flow. I played around by turning the chlorine production to 0 and all lights but the Cell Reversing went off. I Turned rate up to 100% and the Cell Reversing light remained plus the Cell On and Flow Light came on but service light was not on. Trying to make sense of this but not sure what is happening unless this is the Cell going bad and intermittently functioning. Cell does seem to producing as my FC reading is around 7. Trying to limp thru the season if possible. Need advice on what to try next.
 
So I removed the Cell today and thoroughly inspected it. There appeared to be a lot of deposits on the plates. I then performed a vigorous cleaning using a wooden spoon to scrape the deposits I could reach. I then acid washed the Cell for about 15 minutes. There was strong bubbling coming from the Cell and additional pieces of a white substances coming out of it. I reinstalled the cell in the SWG and everything returned to normal operations. I will cross my fingers that it remains that way for awhile.
 
You acid cleaned the cell twice and it started working again after each cleaning. Please post your pool test results. I'm guessing the CSI is very positive for the cell to have scaling that needed to be cleaned twice in a short amount of time.

To prevent scaling in SWG's the CSI needs to be negative.
 
Used pool math to calculate a CSI of 0.6 positive. What do I adjust to lower it.

I am not sure the Cell cleaning actually caused the system (cell) to start working. It may have just been the moving the cell around that caused it. I did notice pieces of white chalk like substance come out from the Cell during the second cell cleaning. Also i used a wooden pop sickle stick to clean off some of this material. Anyway I spent a lot of time today looking at the system with the following results. When the power, Flow and Cell-On lights are on the SWG seems to be working OK and producing chlorine. When the Cell goes in to the Reversing mode the service light comes on and a Code of 121 flashing on intermittently. Could it be possible that one half the cell is good and the other half bad?
 

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Post the test results and we can offer suggestions on what to do to balance the water. You can follow the Recommended Levels to prevent scaling. With the CSI that high your pool is subject to building up scale throughout it.

The cell is worn out on one side of the polarity and needs to be replaced. Your problem is it is an old two port cell and there isn't a replacement cell that will fit in with the plumbing as it is.
 
Ping: THANKS FOR ALL YOUR HELP!

Readings are as follows:
FC 3
TC 3
SALT 3200
CH 240
CYA 70
TA 110
PH 7.6
Pho 80

I am really not in position to purchase a new cell especially given that any replacement would require a re-plumb. Can I use the Cell as is until it totally dies on both sides or should I shut down now and just add liquid chlorine until I can buy a replacement cell or SWG.
 
Those numbers don't even come close to a CSI of +.6. Depending on the water temp using PoolMath I get the CSI around -.18 with a temp of 80 degrees. I'm not sure where you are getting +.6 from.

You can use the cell until it completely dies, I suggest turning it on to 100% output and keep a close eye on the FC. Once you are frustrated enough with the cell then switch over to liquid chlorine.
 
I got confused when doing the original calculations and just redid them and agree with your numbers. My pool tempeature in the day averages around 80 degrees +/- 2 degrees so we are in sync there.

I have cranked up the output of the cell to 100 and running for 8-9 hours a day. I measured again today and read a FC reading of 4 so it is producing some chlorine. I will closely monitor FC and supplement with liquid chlorine when necessary. The cell is over 7 years old so I guess I got the expected life out of it even if I turn it off today.
 
So now both sides of cell are breaking down as I am getting both error codes of 121&120. I saw a rebuilt exact replacement cell be offered for a affordable price from a company called Salt Solutions in Florida. The offer a one year waatnty on there rebuilt cell and it comes with a new cord. Has anyone heard of or purchased from them. I am trying to decide whether to order from them or wait until I can purchase a new SWG system later.
 
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