SC-60 Cell failure in progress?

[YesRushGen]

Hi all,

Our pool was built in Spring 2006, and includes the Autopilot Digital Pool Pilot, and an SC-60 SWG cell.

The cell and unit has worked beautifully, reliably putting out chlorine for 06, 07 and 08 pool seasons. I have cleaned the cell plates, per instructions, at each spring opening. Until now, I have not paid enough attention to it's operation. One huge mistake I have made each year is to NOT shock with an additional source of chlorine. Each year, I would rely on the Super Boost mode to provide the initial shock. Although doing so APPEARED to work at the time, I think that ommission is a contributing factor to problems below.

1. The first sign that I may be having trouble is the "Warning! Check/Clean Cell" message that displays anytime the cell is "ON." When I first saw this I was baffled, because I did clean the cell as instructed with an acid bath.

2. The next warning sign was an FC reading of zero.

Pool size is 33,000 gal, and here's my most recent COMPLETE water test results, taken 4/14

FC = 0
CC = 0.5
TC = 0.5
pH = 7.2
TA = 60
CH = 280
CYA = 50
Temp = 55F
Salt = 3300

After obtaining those results, I added 10 lbs stabilizer to increase CYA, and 2 lbs baking soda to increase TA.

On 4/15, I retested Chlorine only as:
FC = CC = TC = 0... Yep, all zero.

So based on these results, and my bit of reading here at TFP, there's one of two things happening:

1. Chlorine is being used up as fast as it is generated by remaining organics in the pool. In fact, that may explain the change from 4/14 to 4/15, as in the last bit was used up. If so though, shouldn't I be seeing FC now?

or, 2. The cell is simply not generating an chlorine at all, which I can think of two reasons why:

2a. Perhaps the water is simply too cold?

2b. The cell is failing.

To test whether the cell is completely failed, I followed previous advice here and engaged boost mode, and took a sample of water from the partially opened bottom union right past the cell. A quick test showed 2ppm of Total Chlorine.

So, based on that test, I can infer that presently the cell is still CAPABLE of generating chlorine. However, when it is not in boost mode, it is generating none. Zero.

Further, selecting Test Pool Pilot from the Autopilot menu produces:

Power Level 2, 17V, 2.9A (or 3.3A if it is actively generating), and 3300ppm salt.

So... Taking all of this into account, is it possible to tell what's going on?


Thanks!

Kelly

 

[frustratedpoolmom]

I'm by no means an expert in SWG, so hopefully one will chime in. If no one else does with better advice.... I would suggest you shock your pool with liquid chlorine, and with the SWG "OFF" do an overnight test of the FC. If you lose more than 1ppm of FC overnight, it is very likely you have a nacsent algae bloom that is consuming the chlorine as the cell produces it. Perhaps this is causing it not to register chlorine in any mode other than boost. By shocking maybe this will allow the cell to work properly...Hopefully someone with more experience in SWGs will chime in...

 

[Poolsean]

it's a possibility that the cell may be starting to fail, however, I would first check and verify the salt level, and calibrate is necessary.
There are three reasons that the voltage and amperage operate at lower than normal conditions:
1) power to the DIGITAL unit is 110 volts while the unit is internally wired for 220 volts
2) salt is lower than displayed
3) Damage to the display circuit board.

The normal reaction to low salt, cold water temperatures, and scaled or failing cell conditions are 29 volts and low amps.

I would recommend to continuing to increase stabilizer to 70- 80 ppm, especially with spring and summer coming upon us.

Your test of boosting the system and testing the water is smart, thanks for reading and learning. You can run a test by adding chlorine or boosting the system to affect a significant increase in chlorine levels. Turn the Pool Pilot OFF.
Test the chlorine level after allowing the pool to circulate fully, thereby spreading the chlorine level evenly throughout the pool.
Test every 4 hrs (if possible) and record the rate at which your chlorine level drops. Most pools will not drop the chlorine level in a day, so if it does, you've got a high chlorine demand that continual high levels of chlorine will most likely rectify.

Hope this helps,

 

[YesRushGen]

it's a possibility that the cell may be starting to fail, however, I would first check and verify the salt level, and calibrate is necessary.

Hi Sean, thanks for your reply. Copy that regarding salt check. I have manually tested using the optional test strips which I ordered with the TFP-100 test kit. The test indicated 3300, for which I then calibrated the unit. I did that 5 days ago, and the sensed salt level remains at 3300.

There are three reasons that the voltage and amperage operate at lower than normal conditions:
1) power to the DIGITAL unit is 110 volts while the unit is internally wired for 220 volts

If this were the case, would the cell have continued properly the past three seasons? Additionally, (showing my ignorance here) how would I know it was wired for 220? For that matter, how do I know if power to the unit is 110 or 220? If it were incorrect, is that correctable by the pool owner?

2) salt is lower than displayed

Hopefully the notes above regarding calibration will rule this out!

3) Damage to the display circuit board.

God, I hope not! Is there any way to diagnose that?

The normal reaction to low salt, cold water temperatures, and scaled or failing cell conditions are 29 volts and low amps.

That sounds like MAYBE a ray of hope, given that my volts are not at 29, and that the amps are greater than the power level. (I read something here about amps being lower than power level can indicate a failing cell)

I would recommend to continuing to increase stabilizer to 70- 80 ppm, especially with spring and summer coming upon us.

Copy that, I am aiming to hit 80ppm. Side note here: This is the first year I am watching over CYA myself. Upon pool opening this year, my CYA was ZERO. No kidding, zero. Based on the amount of stabilizer I have added this year, I think the local pool shop had been setting me up for a non-SWG pool. Yikes. Could 3 years of lower CYA contribute to early cell failure?

Your test of boosting the system and testing the water is smart, thanks for reading and learning. You can run a test by adding chlorine or boosting the system to affect a significant increase in chlorine levels. Turn the Pool Pilot OFF.
Test the chlorine level after allowing the pool to circulate fully, thereby spreading the chlorine level evenly throughout the pool.
Test every 4 hrs (if possible) and record the rate at which your chlorine level drops. Most pools will not drop the chlorine level in a day, so if it does, you've got a high chlorine demand that continual high levels of chlorine will most likely rectify.

Copy that, so, I can use Chlorine Bleach, per the BBB method. By turning the SWG off, that means setting purifier to 0% correct? I will try this experiment and report the results. Is the hope that shocking will kill the suspected chlorine demand, thereby enabling the cell to take over afterwards?

Hope this helps,

It is incredibly helpful! Even if I have to replace the cell, at least I will know I have tried everything to salvage it, and in addition it was a learning experience. I will know how to PROPERLY treat my next cell and get max life out of it.

Thanks Sean,

Kelly

 

[YesRushGen]

I'm by no means an expert in SWG, so hopefully one will chime in. If no one else does with better advice.... I would suggest you shock your pool with liquid chlorine, and with the SWG "OFF" do an overnight test of the FC....

Thanks, no-longer-frustrated-pool-mom!

This is exactly what Sean suggests, and I will be doing this shock test when I return home this coming Sunday, and will post results.

thanks,

Kelly

 

[Poolsean]

If this were the case, would the cell have continued properly the past three seasons? Additionally, (showing my ignorance here) how would I know it was wired for 220? For that matter, how do I know if power to the unit is 110 or 220? If it were incorrect, is that correctable by the pool owner?
It MAY operate the first year without problems...but probably not likely to be wired 110 volts. However, you may check your circuit breakers it is connected to. If one leg has tripped, it may cause these problems. Trip the breakers and reset them.
The wiring change from 220 to 110 can be done, directly on the power circuit board and is located in the owners manual. You will need the original jumper provided in the installation kit. Let me know if this is the case.


Quote:
3) Damage to the display circuit board.

God, I hope not! Is there any way to diagnose that?
Correction - it may be the Power Module board. To verify, it's basically confirming all the other possibilities first. You may be able to visually inspect the board for damage, burn outs, insect/rodent damage, or loose wires.

Quote:
The normal reaction to low salt, cold water temperatures, and scaled or failing cell conditions are 29 volts and low amps.

That sounds like MAYBE a ray of hope, given that my volts are not at 29, and that the amps are greater than the power level. (I read something here about amps being lower than power level can indicate a failing cell)
Yes, lower amps is one of the conditions of a failed cell. The other is to visually inspect the blades within the cell. For the SC-60 cell, inspect the center and two outer blades for wear on the ends of the blades. It will appear as though the ends are degrading and shorter than the other blades.

Quote:
I would recommend to continuing to increase stabilizer to 70- 80 ppm, especially with spring and summer coming upon us.

Copy that, I am aiming to hit 80ppm. Side note here: This is the first year I am watching over CYA myself. Upon pool opening this year, my CYA was ZERO. No kidding, zero. Based on the amount of stabilizer I have added this year, I think the local pool shop had been setting me up for a non-SWG pool. Yikes. Could 3 years of lower CYA contribute to early cell failure?
YES

Quote:
Your test of boosting the system and testing the water is smart, thanks for reading and learning. You can run a test by adding chlorine or boosting the system to affect a significant increase in chlorine levels. Turn the Pool Pilot OFF.
Test the chlorine level after allowing the pool to circulate fully, thereby spreading the chlorine level evenly throughout the pool.
Test every 4 hrs (if possible) and record the rate at which your chlorine level drops. Most pools will not drop the chlorine level in a day, so if it does, you've got a high chlorine demand that continual high levels of chlorine will most likely rectify.

Copy that, so, I can use Chlorine Bleach, per the BBB method. By turning the SWG off, that means setting purifier to 0% correct? I will try this experiment and report the results. Is the hope that shocking will kill the suspected chlorine demand, thereby enabling the cell to take over afterwards?
Yes and Yes

 

[YesRushGen]

Thanks Sean, I loathe letting this continue until Sunday, but that's the soonest I can do the shock test.

...Side note here: This is the first year I am watching over CYA myself. Upon pool opening this year, my CYA was ZERO. No kidding, zero. Based on the amount of stabilizer I have added this year, I think the local pool shop had been setting me up for a non-SWG pool. Yikes. Could 3 years of lower CYA contribute to early cell failure?

I have been reading in the Deep End forum today... I wonder if the findings of the following thread explain how I ended up with 0 CYA?

degradation-of-cyanuric-acid-cya-t8880.html

 

[chem geek]

As described in this thread it doesn't take long for the CYA in a pool to presumably get consumed by bacteria if the pool is "let go". If upon opening your pool you had a lot of chlorine demand before the FC started measuring, then that's likely what happened. Maintaining a chlorine level over the winter should prevent this.

 

[budster]

As an added thought: If you were not using an external shock, and your CYA was low, you were "burning" that cell at a much higher rate than it could have been run, so your cell life would undoubtedly be shortened. 3 years with those conditions would not be unusual.

 

[YesRushGen]

As an added thought: If you were not using an external shock, and your CYA was low, you were "burning" that cell at a much higher rate than it could have been run, so your cell life would undoubtedly be shortened. 3 years with those conditions would not be unusual.

Thanks, that has been my worst fear suspicions! Hopefully with a shock, I will get 1 more year out of it. We'll see on Sunday!

thanks again,

Kelly

 

[YesRushGen]

Ok everyone, I have now shocked my pool! Below are the details of this, and my initial test results.

Last night at 8pm, I turned my SWG off (0% purifier) and dumped 8 gallons of 6% Bleach in my pool. According to pool calculator, that should've raised my FC (was zero, as previously discussed) to about 15. With the pump still running, I allowed the water to circulate for about 2 hours.

At 10pm, I did the DPD test and obtained FC = 12, CC = 1.5

(edit: forgot to post full test results)
CYA = 75 (up from previous - added more stabilizer several days back)
TA = 80 (up from previous - added Baking Soda several days back)
CH = 250 (down from previous 280 result - probably from not mixing vial thouroughly)
pH = 7.2 (same as previous)

According to info I've read elsewhere here at TFP, This indicates that there is something being destroyed by the chlorine, correct?

At 7am this morning (9 hours later), I did the DPD test again and obtained FC = 10, CC = 1.0

This should indicate that organics are still being destroyed, yes?

I will be able to run the tests again this evening at about 6pm. I am guessing there should be a significant drop in FC, because of the daylight, right?

So, what is my next step in this test? Is my goal to have FC remain relatively constant overnight? (ie, from evening to next morning) And then once I have that, to attempt to run my SWG again once FC has dropped to the normal 2-4 range?

Thanks again, and will post my 6pm results this evening,

Kelly

 

[JasonLion]

Yes, you are losing FC at night, so there is something organic that the chlorine is consuming. You want to continue raising to shock level until the FC level remains the same, or really close, overnight.

If I remember, your CYA level is around 50. With CYA at 50, you should be shocking to a FC of 16. The higher FC level will speed things up a little.

After the FC level holds overnight, you should raise the CYA level up to the 70 to 80 range.

 

[YesRushGen]

Hi Jason,

Sorry, I forgot to include the full complement of tests I ran last night. I have edited my post above to include those. As you can see, CYA is now at 75. According to the CYA/Chlorine chart, I need a shock FC of 28-31. Whew! Assuming my FC stays at 10 until this evening, which I know it wont, I will need to add 11 gallons of 6% bleach!!! Yikes!

Thanks,

Kelly

PS.... A funny side note... Using elements of BBB (I haven't played with Borax yet) has been a lot of fun at my house. One of my housemates submits that he no longer trusts me. lol. He said that in his 15 years (as a kid) of having a pool that he never once saw his dad put Baking Soda or BLEACH into their pool. So I rather enjoy annoying him by putting these household items into the pool. He now runs around the house saying, "why don't you just add some PEANUT BUTTER, or some JELLY to to the pool too?!?!" Haha... All good fun! :lol: I can only imagine his reaction if I ever need to add some borax.

 

[frustratedpoolmom]

Hey Kelly, see if you can find some 10 or 12% from a Pool Store or home improvement warehouse....you'll need less jugs that way, of course do a cost comparison first.

Hope this is resolved quickly for you!

 

[YesRushGen]

Hope this is resolved quickly for you!

Thanks, I hope so too!

You know, it's dissapointing (but enlightening as well) to find out how our PB did NOT tell us. He never told us anything about using external sources of chlorine when opening. He said to just fire everything up, get your water checked, add any chemicals the pool store says you need, put the SWG on Super Boost, and enjoy!

Following that advice SEEMED to work, but apparently at the cost of replacing a cell earlier than otherwise taking proper care of it. At least I know now, and will treat the replacement with the appropriate care. But I'm not totally giving up that this cell MAY last me one more year!

Kelly

 

[YesRushGen]

Ok, everyone, time for reporting of test results!

Last night (about 8pm) I tested BEFORE adding more bleach. FC = 7, CC = 0.5 (this represents a FC of 3 throughout the daytime which sounds consistant with information here at TFP)

I then added 13 gallons of 6% bleach. According to Pool Calculator, that should have raised my FC by 24.4... Adding the 7 from the test result should've landed me at about 31.4 - which is what I was aiming for to obtain shock FC level.

However! AFTER adding this batch of bleach, and allowing circulation for about 2 hours I tested and obtained a whopping FC = 44.0, CC = 1.0. Yikes! Where did all this extra chlorine come from??? :?:

This morning at 7am, I tested and get FC = 39.0, CC = 0.5. (this represents a drop of 5, overnight!)

So, I'm still waiting for that magical night where FC stays close to the same from night to morning.

cheers,

Kelly

PS... I took advantage of the high chlorine level and brushed my liner.

PPS... At walmart, I had lots of strange looks at my basket of 13 jugs of bleach. I got asked by both the cashier & the door guard what it was for. They looked skeptical at my explanation. I also remembered someone here joking about saying, "it's to clean up all the blood," and how much fun it would be to see the reaction to THAT! :lol: But I didn't have the guts to do it.

 

[frustratedpoolmom]

Yikes!

Did you add the jumbo wal-mart jugs? Those are more than a gallon... 174 oz like a gallon and a half.

If I ever have to buy that much, I'm totally gonna say that.

 

[YesRushGen]

Yikes!

Did you add the jumbo wal-mart jugs? Those are more than a gallon... 174 oz like a gallon and a half.

If I ever have to buy that much, I'm totally gonna say that.

Wow, nice spot. That is EXACTLY what happened. :grrrr: I just had roommate check the empty jugs and lo and behold... 174 oz. 13 of those is 2262oz, and pool calc says that will raise FC by 33.2. When I add my original 7, there's the levels of 40 I am seeing.

At my CYA of 75, it looks like I unintentionally broke the Mustard Algae threshold!

If you ever DO say that, you have got to share the tale with us!

Kelly

 

[YesRushGen]

Ok everyone, test results are in from last night and this morning!

I will recap all the results here for convenience: CYA during this time is/was 75. In addition, pool has been crystal clear during all this. Further, filter pressure has remained at 14lbs during all this.

4/19 8pm: Added 1392 oz of 6% Bleach
4/19 10pm: FC = 12.0, CC = 1.5
4/20 7am: FC = 10.0, CC = 1.0
4/20 8pm: FC = 7.0, CC = 0.5
4/20 8pm: Added 2262 oz of 6% Bleach
4/20 10pm: FC = 44.0, CC = 1.0
4/21 7am: FC = 39.5, CC = 0.5
4/21 8pm: FC = 33.5, CC = 0.5
4/22 7am: FC = 30.5, CC = 0.5

So, at this point FC is continuing to fall at night. Given this continued nightly loss over several days nows, and that filter pressure is not increasing, and that the pool is crystal clear, can we say this is a bacterial infection that's being knocked out?

At any rate, I will not be home again until Saturday evening to re-bleach, if necessary. I'm hoping the overnight loss will stop by the time I return home. I have assigned a roommate as proxy tester, in my absence. haha. If the RATE of decrease I am seeing is constant, I should be lucky enough to have some FC left when I return.

On a side note, I have tried to explain to everyone at home that this is a drawn out process that could take several days, and that patience is to be excercised. In spite of that, however, everytime I run a water test, everyone hovers around my inquiring, "SO IS THE CELL DEAD???"

Thanks,

Kelly

 

[YesRushGen]

Although not home yet, I have just learned from my proxy tester that the FC has stopped falling overnight, and that there are no CC's presnt. I will post details of the test results by tomorrow.

Encouraging, I think, that at least the shock has worked. Now, let's hope the SWG outputs some chlorine once the FC falls back to normal range.

That's a good question there, at what FC reading should I begin trying to use the SWG?