APURE35 Ei Check Salt Error


New member
Mar 31, 2017
Cedar Park, TX
I have a Jandy APURE35 Ei manufactured FEB 2010. It appears that Jandy (Zodiac) has another type, PLG model with separate sense line pod. I have the single, integrated unit. I just replaced the cell with Zodiac R0511400 35 Electrode for $197. I have confirmed the wiring is connected and correct on the electrode posts and I have confirmed the red, black, and blue cables are securely connected to the power supply terminal on the far end. The controller PCB ribbon cable is also connected to the power supply base correctly.

I completely cleaned my DE filter blades with new DE, and have correct starting pressure of 22 psi. I have proper water flow in the cell compartment. I had 3600 ppm of salt and raised that to about 4100 ppm, per Jandy's owner manual. As of yesterday, my TC/FC was 5 ppm due to recent shocking and pH was 7.6. Other readings measured two weeks ago at pool shop: TA 80 ppm, CH 250 ppm, CYA 40 ppm (should be 60-99 ppm). Also, Cu and Fe are zero, Pho is 100 ppb . Have not increased my CYA due to recent shocking as TC/FC was zero before I found this issue.

When I turn on the primary pump, the Jandy will turn on with red flow light, then turn it off once the water flow is detected. The unit sets the first of the six strength LEDs to yellow and the Salt LED is yellow. The LCD displays:


Pressing Output does nothing. Note that weeks ago, pressing Output would get me up to two green strength LEDs, then the 3rd (or 4th) press would drop it down to one yellow LED and yellow Salt LED came on. This had me thinking my salt was getting low.

During my unit disassembly review, I saw the outer soft shell membrane has additional secret button overlays which are clearly visible in Google images on the rear view of the cover and on the front view of the control PCB. Pressing the far right hidden button PB1 (about an inch after the "y" in "Jandy" directly below the Salt LED, will reset the unit and display the following during initial boot up:

EI Series
V2.0 DEC 2009

Then, it returns back to the check salt condition listed above. Note that a visible review of the PCB shows the main IC has a Ei USA V2.0 JAN 2010 white sticker. I did notice that the Sunon 40 mm cooling fan is not working, but it has no RPM sense line to detect it. I question its effectiveness here in the Texas heat. :) The Zodiac R0512300 TS Control PCB Assembly Replacement is $160, so I wanted to understand more about what the hidden buttons can reveal about the state of the controller PCB. If you review Google images, there are a few that show the metal layer labels in the PCB under the green coat. Here is a rough layout of the LEDs (Dx) and push button switches (PBx) as seen from the front:

[FONT=courier new]
         D12 D11 D10 D9 D8

  Flow D19                 D7 Salt
     On/Off PB6     PB7 Output

      PB2      PB5        PB1[/FONT]
So only PB6 and PB7 are presented to the user as On/Off and Output, respectively. This differs from the PCB labeling at the trace layer (visible under the green coat) which may be remapped in actual firmware? Here is a summary:

PB1 Reset
PB5 Timer
PB2 On/Off
PB4 Output
PB3 Clock
PB6 (can't decipher from photo)
PB7 (can't decipher from photo)

Only PB1 responds to single press with reset. I did not get too adventurous. Want to learn more first.

  1. Based on my chemistry listed above, the cell should be able to generate, correct?
  2. Does anyone know the command operation for the hidden buttons on the control board? I read these manuals are locked down on the corporate site. Unless I was to open a pool business? ;) I want to perform a full diagnostic, view/re-calibrate the salinity reading, and reset the cell operating hours.
  3. Does anyone know the blue flow/salinity sense line details? Looking at the simplicity of this double-sided PCB, maybe only a buffer IC or resistor is bad? I could easily replace these components and save $160 dollars.
  4. I saw in another thread that this APURE35 Ei model does not provide a salinity ppm reading on the LCD? Is that true? If not available via secret button command sequence, is it available via the Aqua Link RS control interface on the RS-485 port?
  5. Is there a wide range of PCB control versions released, where you want to avoid version X or seek version Y?

And that should about do it for this first request. :D


New member
Mar 31, 2017
Cedar Park, TX
I forgot to add that my water temp has ranged from 70-76 ° F during my daytime debugging. I took out the PCB and cleaned it. I was able to read the remaining button text.

PB1 Reset
PB5 Timer
PB2 On/Off
PB4 Output
PB3 Clock
PB6 Hours
PB7 Mins

A deep Google search with new set of keywords uncovered the Zodiac Academy Technical Training Maintenance Manual - AQUAPURE(R) Ei Workbook (circa May 2015). The manual explains using PB5 to manually reverse polarity for cell cleaning and set duration. And how to patch wire between blue and black from the cell to trip active low signal to debug cell even if flow sensor is bad. And several other things.

Here are some excerpts for the TL;DR crowd, and to capture information if the URL changes:

Check Salt
The ideal salt level is 4000 ppm and the ideal water temperature is 80º F. The CHECK SALT light will illuminate & the LCD will read “Check Salt”
• If the water temp is below 65º F
• The salt level is below 3000 ppm or
• There is a combination of lower than ideal salt & lower than ideal water temperature.
Note: A cell which is damaged or dying out can also activate the CHECK SALT light.
• If the salt level is down 10% you lose approximately 8% output
• If the pool water cools down to 20 degrees F you lose approximately 20% output
• If voltage to cell is down 10% due to wear then approximately 18% of the output will be lost.

Skimmer Box Test
In cold weather if the “Add Salt” LED activates it could be caused by the temperature of the water. Test by doing the following:
• Turn the Ei to 100% output.
• Add a large handful of salt in the skimmer box.
• Wait 30 seconds.
If the “Add Salt” LED goes off it confirms the cell is good and the loss of current is due to the cold water or lack of salinity in the water.

Display Shows Clean Cell or Test Cell
• Has the cell been cleaned?
• Are the wires connected and in good shape on both the cell and Power Pack?
• How old is the cell?
• Is the cell still producing? You can see the effervescence in the cell when producing.

To access the Chlorinator/Cell hours:
• Turn the Ei OFF.
• Press and hold the secret ‘REVERSE’ button behind the Jandy logo.
• Wait approximately 6 seconds, then the hours will appear.
• Press the ON/OFF button to return to the normal operating screen, OR
• Press the OUTPUT button to clear the CELL HRS (this should be done when the cell has been replaced)

Hard Reset
The Ei has a ‘hidden’ HARD RESET button located to the right of the Jandy logo, that can be used to reset the microcontroller.
This button is located as shown in the picture. Press to RESET. (Far right of the bottom Jandy text, see photo in PDF)

Additional Information
• All settings are saved using the backup battery as well as EEPROM memory in case the battery runs flat. The battery life is 500 hours. They are NiMH batteries and are not replaceable
• When connected to a controller and SPA mode is selected at the controller the output of the Ei will drop to 20% (minimum)
• When connected to a controller and BOOST is selected at the controller, the output of the Ei will go to 100%.
• The correct output current is 5 Amps +/- 5%. The output voltage depends on the cell condition, salt level and water temperature. When running @ 4000ppm Salt & 80° F with a new cell the Ei output voltage will be around 21-22VDC.
• If either or both fuses on the PCB are blown, replace the PCB.

Based on the last paragraph, you can measure current and voltages with a meter. Note that the power pack area has 120V input, so be very careful. If you are not experienced with electricity, then KEEP OUT folks! Call a trained professional!

The main microcontroller is a Microchip PIC18LF4620. There is a manufacturer debug/test port on the bottom of the PCB that might be RS-232? It could open up more diagnostics if it's not locked. :D

I'll keep at it and update as I learn more.


New member
Mar 31, 2017
Cedar Park, TX
Here is some additional data from the PDF that I am missing above:

• Ocean water – 35,000 to 36,000 ppm.
• Tear drop – 7,200 ppm.
• Ei – 3,500 to 4,000 ppm.
The purer the salt the better. Calcium & Magnesium are enemies of the cell.
Pure NaCl
• Minimum 98% pure food grade NaCl
• No added anti-caking agents.
• No sodium ferrocyanides (aka yellow prussiate of soda)
• Non-iodized

When power is first applied to the Ei, it will display the software revision, then default to Off.

Polarity Reversal
• The Ei reverses polarity every 5 hours of operating time.
• When reversing polarity, “CLEANING” is displayed.
• The Ei powers down for 5 minutes and the output lights drop to 1 amber light. After reversing polarity, it powers up to the previous output setting.

Manual Polarity Reversal
• The polarity of the Ei can be manually reversed by pressing the ‘hidden’ REVERSE button under the Jandy logo for ~4 seconds.
• The output at the cell will turn off momentarily, the polarity will reverse and the output will turn back on.

Change Polarity Reversal Time
The Ei is set to reverse polarity every 5 hours.
This can be changed to every 2.5 hours.
Press the ON/OFF button and the hidden button (under the Jandy label) simultaneously.

My water temp was 72° F this morning. I ran through the manual polarity reversal and the unit switches over to ON ** NO FLOW! **, instead of listing the ON CLEANING text and dropping to a single amber LED per the manual. At this point, I try to cycle the polarity again and I just see a single amber LED on the strength row turn on and off of a second with display stuck on ** NO FLOW! ** and Flow LED on. I have to do a hard reset to get it back to the usual ON CHECK SALT condition. I can repeat this sequence, same results.

I measured the voltage on the red/black pair while running and in polarity reversal. The bare wire is a little exposed at the end of the electrode plugs, so I did not have to take the whole cover off.

Normal Polarity: 0.58VDC
Reverse Polarity: 0.67VDC

Note that I can cycle the reversal interval as shown above. I think this control board is working correctly and I am starting to think the power unit is bad? It may not be able to generate the power for normal and reverse polarities.

I ran the commands to display the unit operational time and get the following:

CELL HRS: 8584
CHLOR HRS: 18630

I cleared the cell operating hours per the manual and cycled the power. It did not change anything. Assuming previous owner kept the current operating schedule, this unit runs maybe 8 hr/day x 365 = 2,920 hrs/yr, so a little of six years of service? Might be time to replace power PCB. Does anyone have experience with this unit and expected operating hours?

The cost to replace the Zodiac R0512100 Power PCB Assembly is $260. Would be nice to patch into RS-485 comms port to try and learn more about the state of the board. This thread looks promising, but it will take me further down the rabbit hole. :)


New member
Mar 1, 2018

I am having a similar problem. I replaced the Salt cell and now the LED lights turn on and then turn off immediately after like 10-15 seconds. I am not sure what the issue is.

Could you please assist or point me in the right direction.