Hayward T-15 Cell struggling to maintain proper FC Level

[mzollars]

Hi All, first time poster here. I have done my best to study up on pool school, thanks so much for all of the valuable information.

I have an issue I am struggling to figure out as it relates to my FC Levels. Starting a few weeks ago, when testing FC levels, it was always low around 1ppm, so I have started to add a gallon of bleach every 2-3 days.. I have learned I need to start testing this daily and start noting overnight FC loss. There are no obvious signs of Algae that I can tell, water seems clear, maybe a hair cloudy.

After troubleshooting I focused on a possible faulty cell that is only 10 months old. I inspected the cell and there is no calcium buildup, no lights are on, At 65% output, plenty of pump run time. 7am-11am 2000 rpm, 11am -3pm @3000 rpm, 3pm - 9pm (2000rpm), but yet I have low FC levels if not adding supplemental bleach.

We have had a lot of rain lately, so not sure if that is big factor or not.. I do have an Auto-fill (city water) and Drain.

I submitted a warranty service request.. tech came out and tested the cell and said it is working fine. He said all test results look good except for CYA over 100!?

I am now questioning if I am doing the CYA testing correctly, and if I have the Chlorine Lock myth going on that is cancelling out salt cell production.. Seems regardless some condition is eating up my FC levels. I have ordered more of the CYA reagent (big bottle) for future testing, should arrive tomorrow as I am about out..

Trying to figure out if I challenge the Tech's assessment of Salt Cell working ok, or proceed with some course of action for my pool chemistry that will allow my salt cell to maintain FC on its own

Current Test Results as of 11:30 am today (after adding 3/4 gallon of bleach last night, and another 1/4 gallon this AM):

FC - 4
CC -.5
Ph - 7.6
TA - 90
CH - 370
CYA - 40
Salt - 3200

I went to pool store just to see their results of same time of day sample, here are those results:

FC - 3
CC - N/A they don't test, TC -3
Ph - 7.7
TA - 100
CH - 350
CYA - 50
Salt - 2900

I have all details in my signature.

Any thoughts or suggestions are greatly appreciated!

 

[JohnT]

Welcome to TFP!

A quick check for cell function is to take a sample of water from in front of the return. If the SWCG is producing chlorine, that sample should test higher than the rest of the pool.

If your water is a hair cloudy, it's possible you are just barely containing algae. If you follow the SLAM Process process for a few days you might see an improvement.

 

[mzollars]

Thanks John!

Appreciate the prompt response.

Forgot to mention that I am struggling to decide if I follow SLAM for a bit as you suggest, or first quadruple check the CYA?

I am now paranoid after the service tech claimed a reading of 100+... so at first I was thinking I needed to let some water out of pool to lower CYA and see if FC improved via the SWG alone.. but my test and pool store test is showing CYA around 50.. the other day it was 60 before Hurricane Michael outer bands filled up the pool.. had been trying to get in the 70-80 range, and now I am spooked I added too much and questioning the accuracy for my Taylor Kit CYA test.

I guess I will go stock up on some bleach and prepare to SLAM until FC holds to less than 1ppm loss overnight, and hopefully CC drops to 0.. Also, will test a sample from in front of return in the near term to see if it is higher to confirm SWG function.

If after all of this, SWG still doesn't seem to be doing its job, I will submit a rebuttal to the tech's findings and see what happens.

 

[JamesW]

What are the diagnostic readings for the Aquarite?

 

[mzollars]

Aquarite Diagnostics:

Avg Salt - 3200
Pool Temp - 86
Cell Voltage -31.0
Cell Amperage - 0.00 (just noticed this, had been greater than zero prior to tech visit. Salt levels in range, cell inspected twice recently)
Output % - 70p
Instant Salt -0
Auquarite Model - AL-0
Software version - r1.59
Cell size - t-15

Power light is on, Generating Light is on

 

[mzollars]

What are the diagnostic readings for the Aquarite?

Went back out after noticing the Cell Amperage and toggled it off, cut power via circuit breaker, back on and now get the following:

Aquarite Diagnostics:

Avg Salt - 3200
Pool Temp - 86
Cell Voltage - 25.5
Cell Amperage - 6.54
Output % - 70p
Instant Salt - -3100
Auquarite Model - AL-0
Software version - r1.59
Cell size - t-15

Power light is on, Generating Light is on

 

[mzollars]

As of 3:15pm today test resuts for FC has reduced to 2.5 compared to 4 at 11:30am today (it has been pretty sunny, pool has no shade). Sample was from near a return closest to equipment.. will test again in a few hours.. I suppose I should add another gallon of bleach..

I just ordered a couple of 10 pack cases of bleach to prep for SLAM

Also, I added 1.5 cups of acid to nudge the PH down closer to 7.4, will test PH again on next test session

 

[JamesW]

The diagnostic numbers look good. If the instant salinity is correct, the cell is working correctly. It's really that simple.

Verify the actual salinity and if the AquaRite instant salinity is close, it's working. Divide the Instant salinity by the actual salinity and that will give you the cell performance.

For example:

Instant salinity........Actual......Performance

3,400....................3,200............106%
3,200....................3,200............100%
3,000....................3,200..............94%
2,400....................3,200..............75%

Salinity reading are +/- up to 400. So, you have to factor in some margin of error for the tests. For cell performance, you want to look for trends more than a single difference unless the difference is more than about 800 ppm.

Cycle time is 180 minutes. At 70%, the cell generates for 126 minutes and is off for 54 minutes. It then reverses polarity and begins a new cycle. While in the off portion of the cycle, the Power and Generating lights will both be on, which can be confusing. During the off part of the cycle, the amperage and Instant salinity will both be zero.

14 hours at 70% will produce 9.5 ounces of chlorine, which is 4.7 ppm in 15,000 gallons. That should usually be enough. But, it can be insufficient if the chlorine gets behind and algae has gotten started.

Do a SLAM to clear the water and then you should be fine.

 

[mzollars]

The diagnostic numbers look good. If the instant salinity is correct, the cell is working correctly. It's really that simple.

Verify the actual salinity and if the AquaRite instant salinity is close, it's working. Divide the Instant salinity by the actual salinity and that will give you the cell performance.

For example:

Instant salinity........Actual......Performance

3,400....................3,200............106%
3,200....................3,200............100%
3,000....................3,200..............94%
2,400....................3,200..............75%

Salinity reading are +/- up to 400. So, you have to factor in some margin of error for the tests. For cell performance, you want to look for trends more than a single difference unless the difference is more than about 800 ppm.

Cycle time is 180 minutes. At 70%, the cell generates for 126 minutes and is off for 54 minutes. It then reverses polarity and begins a new cycle. While in the off portion of the cycle, the Power and Generating lights will both be on, which can be confusing. During the off part of the cycle, the amperage and Instant salinity will both be zero.

14 hours at 70% will produce 9.5 ounces of chlorine, which is 4.7 ppm in 15,000 gallons. That should usually be enough. But, it can be insufficient if the chlorine gets behind and algae has gotten started.

Do a SLAM to clear the water and then you should be fine.

Thanks James!

In Day 3 of a SLAM.. CC is zero, water is clearer, still losing more than 1 ppm of FC overnight (around 2ppm). Will see how it goes tonight.

 

[mzollars]

Lost 3 ppm overnight...

I just brushed under a tiled table we had installed in the pool.. poured a cup of bleach in the auto fill, and took out the pool umbrella from the underwater sleeve in the large sun shelf!!

There was obvious funk and debris in the umbrella sleeve, so hopefully that was the culprit.

Topped back off to 16ppm based in CYA of 40.. will check FC after dark and see how we do overnight.

 

[JamesW]

Ok, hopefully you're getting close to the end of the SLAM.

 

[mzollars]

FC Loss of 1.5-2 ppm overnight.. bumped FC back up towards 16 and will repeat again tonight

 

[mzollars]

Still losing more than 1ppm of FC overnight... SLAM continues..

I had a table built into the pool (2.5' x 2.5' square), the column support of the table has the pebble finish. And the table top and sides is tiled with glass tile, however the underside of the table is bare concrete that was poured to form the table top.. I brushed the heck out of that suspecting that could be my problem..

Is the unfinished bare concrete, underside of the table going to be a long term problem that I need to have the pool builder address? Or since it is a small area, just need to be sure I brush under there thoroughly and regularly?

 

[Catanzaro]

Is the unfinished bare concrete, underside of the table going to be a long term problem that I need to have the pool builder address? Or since it is a small area, just need to be sure I brush under there thoroughly and regularly?

If water does not circulate well in this area, then brushing is the solution, without exception. At least once per week. If your water has been crystal clear for a few days, and you are performing your OCLT at these levels (16 or around there) and repeatedly failing the test, allow your levels to drop under 10 (right around there), and then perform the overnight test. You can also track your 24 hour results. For example, if you test 16 at 10 p.m. and then 24 hours later, you test 12-13, then that is a clear sign that your pool is in good shape. Difficult to determine how much your pool should be consuming unless you have a detailed history from the past. You must pass the overnight test, although recommend allowing levels to fall under 10 before performing the test.

 

[mzollars]

If water does not circulate well in this area, then brushing is the solution, without exception. At least once per week. If your water has been crystal clear for a few days, and you are performing your OCLT at these levels (16 or around there) and repeatedly failing the test, allow your levels to drop under 10 (right around there), and then perform the overnight test. You can also track your 24 hour results. For example, if you test 16 at 10 p.m. and then 24 hours later, you test 12-13, then that is a clear sign that your pool is in good shape. Difficult to determine how much your pool should be consuming unless you have a detailed history from the past. You must pass the overnight test, although recommend allowing levels to fall under 10 before performing the test.

Thanks for the feedback.

I really brushed the pool thoroughly today.. got in with a mask and did it all up close.. saw plenty of dust come out from under the table and also along the walls.. not sure if what I was seeing was residual plaster dust or the initial stages of Algae.. I also vacuumed, got the crud out of the umbrella sleeve (screwed the cap on as well), and turned off the auto fill supply for now.

The pool is a bit cloudy again from the vigorous brushing.. FC had dropped to 6 naturally over the past few days so I adjusted PH while I could.. SWG remains off.. pump is running 24 hours.

I think I overdid the bleach tonight, not sure where I miscalculated but FC is now up to 21 as of 8pm..

Will wait till the water is clear again, and FC is at 16 or below before trying OCLT again. Fingers crossed I can wrap up the SLAM this weekend.. started last Friday night.

 

[Catanzaro]

If the water has remained clear for approximately 3 days, and you repeatedly fail the OCLT at higher levels, then allow your levels to drop to around 10 or slightly under. Remember that with testing error and chlorine being broken down by a percentage and not a flat amount, it is sometimes quite difficult to pass the test at higher levels.

 

[mzollars]

As of 6:40am, FC is 20 after showing 21 last night. Not sure if I should be celebrating or not.. will probably keep going with SLAM with pump running but no more bleach for now... will allow FC to drop to 10 or a little less and try OCLT once more. If I pass again and all looks clear will end SLAM and start working on getting my CYA back up to 70-80

 

[Catanzaro]

As of 6:40am, FC is 20 after showing 21 last night. Not sure if I should be celebrating or not..

Yes, you should be celebrating. Do not go crazy over this. Allow your levels to drift down and maintain (at least for a week or maybe a little longer), higher than normal chlorine levels based on your CYA. Maintain your levels based on a NON SWG Pool. After a few weeks, if your pool is in great shape, then bring the levels down to the SWG recommended levels. Keep an eye on your levels at lower levels, and maintain a brushing schedule weekly.