Suspect Issue with SWG - Thoughts?

[FattyLumpkin]

Hey all - having trouble keeping my FC up despite continuing to ramp up both my pump run time and SWG %. I'm presently running 11 hours a day at 100%, and noticed a 3ppm FC loss since yesterday (not an OCLT result, and we swam yesterday).

Anyway, my current results:

FC 3.5
CC 0
CYA 80
pH 7.6
CH 250
TA 100
Salt 4000

The pool is covered all night and any time during the day when it is not in use (which is most weekdays), yet I continue to struggle. I shocked to 25ppm (no, not to SLAM level for my CYA, so that also could be a problem, I guess).

At this point, should I suspect an issue with the cell? I have not cleaned it this year...

Any input would be appreciated. Thanks!

 

[pooldv]

You can inspect the cell but don't clean it if scale isn't present. Cleaning will shorten the life of the cell, especially if cleaned when scale is not present.

Doing an Overnight Chlorine Loss Test is the best way to check for organics in the water consuming chlorine.

 

[FattyLumpkin]

OK, I will do an OCLT tonight.

Assuming that clears, though, if no scale and no lights are on the IC-40, then it's unlikely there's an issue with the SWG? Are there any other signs I can look for that might point to a faulty cell?

 

[Rossterman]

You can measure the clorine level from a pool return amd compare to the pool water to verify working and how much is being produced. You should also see small bubbles the the return water that are created when chlorine is produced.

 

[pooldv]

How old is the cell?

11 times out of 10 when a SWG cannot "keep up" it is because of algae and organics in the pool water. For an IC40 to have all lights green and not produce chlorine is unlikely. It would give a check cell error or a salt error or the cell light wouldn't light or something.

 

[FattyLumpkin]

@Rossterman: Thanks! I'll try that...

@pooldv: I like your ratio of 11 out of 10. The pool was installed in 2012 by the previous homeowner, so it's 4 years old at a maximum. I've read 4-5 years as the average life of a cell -- is that accurate to you? Anyway, I'll do an OCLT and see what's going on...

 

[mgmoore7]

As suggested above, do the OCLT. At 3.5, you are below the minimum for CYA of 80 and that would increase the chance that something is growing already.

Take a look at the chart below to help you determine run time assuming it is working optimally and there are no organics growing. This was a eye opener for me. 11 hours at 100% may not be far off depending on the FC demand you normally have. 2 to 4 is common.



If you pass the OCLT, I would suggest that you bring your FC up to about 9 using bleach and then dial in the pump run time and SWG %. That way, if you are little low, it will stay above the minimum even if you make a mistake and set it to 0 rather than 100%. After you "dial it in", you can let it fall to your Target of 6. Right now, for me I feel more comfortable a little higher.

 

[FattyLumpkin]

Matt, thanks a ton! Where did you grab those run times from?

 

[mgmoore7]

It is from a calculator that I did in Excel. Link is in my signature.

 

[pooldv]

The cells are rated for 10,000 hours of production time. There is a way to check cell life but I can't remember the secret code. Something like hold down the more button with your left eye closed and do a cartwheel. Check the manual.

8 hours x 7 days x 16 weeks = 896 hours
Hmmm, never actually tried to do that math before. 10 years seems higher than what we usually hear.

 

[FattyLumpkin]

It is from a calculator that I did in Excel. Link is in my signature.

Very cool! Thanks.

 

[FattyLumpkin]

Performed an OCLT last night... recorded 4 FC last evening, and 3.5 this morning. So it seems I passed that test. Think I'll take all the advice here and add some bleach to bring it up to ~9FC, and also up the run time. Just hard to imagine I'm going through 8+ FC a day -- does that not seem high for a pool covered all day that passed the OCLT? So if it is indeed too high, then I think I may not be getting the ~7 FC from my SWG and that may be the culprit. Thanks again for everyone's input.

---------

Actually, I misread the calculated results. Looks like @ 11 hours run time and 100% SWG, I'd get roughly 3 FC, which seems more reasonable to burn through in a day.

 

[zea3]

By keeping the pool covered all day when not in use you are not allowing the sun to help burn off the CC. I imagine your FC is trying to burn off the CC that accumulates after you swim. Try letting your pool "breathe" for a few hours and see if it makes a difference.

 

[FattyLumpkin]

Interesting, zea. Thanks for this. Would my CC be elevated if this were occurring? It's steadily 0 (or very rarely 1) drop to bring it clear again on the chlorine test.

 

[FattyLumpkin]

Also, I was always under the impression that the UV consumes FC, not CC (or at least both)? Time for a refresher at Pool School for me...

 

[pooldv]

Yes, both consume FC. CC can be a fleeting thing. You don't always catch it in measurable amount to but it is always going on in the pool. The main reason CC can build up is in the presence of low FC where it can't burn off quickly.

Yes, you are correct that your FC consumption will be lower with a cover than without.

 

[FattyLumpkin]

Thanks, pooldv. I worded my question wrong: I was always under the impression that the UV consumes FC, and that the UV does *not* consume CC. Is this a true statement? Just trying to confirm if leaving the cover off during the day might improve things (it's especially hot for MA right now - low 90s).

 

[pooldv]

UV consumes FC and CC.

 

[isriam]

hold down both buttons on the ic40 for the life meter.

 

[Hoster]

I ran into a similar issue and in short, my T-CELL-9 (up to 25K) is not sufficient for my 25K pool. I ordered a generic T-CELL-15 (up to 40K) based on TFP members' recommendation (2.5 - 3 times). I even ran my cell 100% 24 hours but can't keep up in this sun (CYA of 100, too). Not sure what your CL generating capacity is (this like does not have PENTAIR - Discount Salt Pool - Compare Chlorine Generators and Chlorinators) but you may want to check.