Pool Pilot low chlorine

In the last 5 yrs since installing our pool with the Pool Pilot SC-36 system we've had our share of issues, for example we're on our 3rd tri-sensor assembly and 3rd power cord to cell. The unit has had the check/clean cell on and off for years now, after repeatedly checking and cleaning the cell and replacing the cell when necessary and having it generally operate properly when the tri-sensor and power cords were working I eventually ignored the alarm. I replaced the cell about a year ago and the system operated well since then up until early July of this year (though alarm continued to come in and out). This spring (when the system was still working well) it could keep the pool's chlorine level at 5 ppm at the 85% setting on power level 2 with the water temp in the upper 70s. Since July the system has not been able to maintain any chlorine level, I've had to use liquid chlorine to keep the algae from taking over though we have had some minor blooms to deal with. Last weekend the "low amps" message began appearing on the screen. I removed the cell and cleaned it, there was a bit of scale on the inlet end of the plates but not so much that I would expect to have a noticeable impact on operation. There was also no detectable difference in the length of the plates so I don't suspect the cell is worn out. Afterward, I ran the system test several times with boost mode on and consistantly got readings of 12-14 volts and 3.2-3.5 amps. From reading other posts I'm aware that this is low amperage. Today I ran the test and was encouraged to see 18 volts and 6.5 amps, though when I ran the test a couple hours later I saw 17 volts and 3.4 amps. I like the benefits of the salt system when it is working, but I have to say this thing has been so difficult and expensive to keep working that I am tempted to go to a chlorine feeder. I want to give it one more try to get this thing working, can anybody provide any guidance?

Today my pool chemistry tested as follows:

Total Chlorine: 0.5ppm
Free Chlorine: 0.5ppm
pH: 7.4
Total Alkalinity 120 ppm
Calcium Hardness: 400 ppm
Stabilizer: 90 ppm
Total dissolved solids: 4800 ppm
salt: 3100 ppm
Water temp: 86 degrees

I can't answer your question, but I can alert the guy who should be able to help you. I'll shoot him an email now, and hopefully he'll pop in soon to help you out.

Welcome to the forum!

Have you added any other chemicals to your pool other than chlorine or acid?

The fluctuating amperage is suspect. I want you activate the BOOST mode, let it run 1 minute, then run the TEST POOL PILOT and record the displayed diagnostics. Then go to MAINTENANCE MENU and perform a FORCE REVERSE. After this, run another TEST and see if the amperage changes.

membership upgraded.

. . . in case you didn't notice, you are getting help directly from AutoPilot.

Sean, Thanks for the response, I've been out of town so could not respond to you until now.

Regarding chemicals, each week I add ~1/4 gallon of acid to keep the PH ~7.4 ot 7.6. The weekend prior to the chemistry I reported in my 8/18 post I added some stabilizer and I added a quart of a chemical used to keep the calcium from plating out in the cell and on the pool finish, I'm embarased to say that I don't know what the chemical was other than there were 2 products to choose from, 1 whose levels could be detected in a pool water test and the other that could not, I bought the one that could not be detected. That weekend I also added some salt as well. Please note that my issues with maintaining chlorine level goes back well prior to that point.

After reading your 8/20 post this evening I went out and ran the system test and got some data.

Chlorine level at 6:30 this evening: 1 ppm according to my home test kit (after running system at 100% all week since my 8/18 post, please also note that typically when my home chlorine test kit shows 1-2 ppm chlorine then I have my water tested at the local pool supply store the same day they tell me there is 0 ppm chlorine so my home test kit's accuracy is in question. Judging by the fact that the pool has some algae "shadows" on the pool walls I would say I believe the chlorine is currently 1 ppm or less. After taking this reading I turned on the boost to let the system run overnight and immediately ran a test of the pool pilot and it showed 18 volts and 6.5 amps.

3 hours later I read your post and then ran another pool pilot test and saw 18 volts and 6.5 amps. I did a force reverse and tested, it showed 18 volts and 6.4 amps. I waited about 1 minute increments to run more tests and got the following results 17 volts and 6.3 amps, 17 volts and 6.2 amps, 17 volts and 6.2 amps. I waited ~15 minutes and tested again getting 18 volts and 6.5 amps.

Any help you can provide would be greatly appreciated. I'm very concerned because the system failures we've had over the past few years have led to some small flecks of black algae in different areas of the pool, I can't afford to run with low chlorine for any period of time going forward.

Kevin Gobeil

8/26 update:
Had pool water tested today:
Total Chlorine: 2.0 ppm
Free Chlorine: 2.0 ppm
pH: 7.8
Total Alkalinity 105 ppm
Calcium Hardness: 360 ppm
Stabilizer: 50 ppm
Total dissolved solids: 4200 ppm
salt: 2800 ppm
Water temp: 83 degrees

I'm actually encouraged that the chlorine was not 0 as it had been the last couple weekends when I brought samples in. I ran the pool pilot test a few times, now getting a reading of ~14-16 volts and 3.4-4.0 amps while the "check/clean cell" light was on. Ran test after "check/clean cell" light went off and got 18 volts with 6.5 amps.

Based on the water test results I added ~1/4 gallon acid, this is typical I add this weekly, and I added 2 lbs of stabilizer and a 40 lb bag of salt. Then I brushed all of the pool surfaces and added 2 gallons of liquid cholorine because I had a light shadow of algae on some of the pool walls, this brought the free chlorine up to 5ppm+ (above scale on my home test kit).

Most home SWCG units will NOT keep up with chlorine demand, while you have active algae growing. With a CYA=50 ppm, you DEFINITELY need to read the Best Guess page, linked in my blue signature bar.

Use bleach to raise the pH -- to the DARK yellow - orangish-yellow OTO range. If you want help with doses, please complete the pool chart:

Pool Chart Entry Form

I agree with Ben. Let's treat the algae first, then we can deal with the FC levels.
The amps and volts are in the proper range, other than when the Check System light comes on and the voltage and amperage drops.

My best guest is that the cell is worn out on one side, moreso than the other side.

To confirm, when you get the Check System light, lift the cell cord off and move it over to the other holes in the cell cord.
The cell cord has three holes, two of which are used with the SC-36 cell.
(That is, if I number the holes on the cell cord as 1, 2, 3 and the prongs on the cell A, B. Assume 1 is on A and 2 is on B, lift it off and place 2 on A and 3 on B.)
Make sure when you do this, there is nothing in the third hole (there should be a red plastic insert cap). By doing this, you've reversed polarity on the cell.
IF the message goes away, then the cell is worn out on one side and not the other.
IF the message stays, then it's possible that the Power Module is damaged and not reversing properly.