High Cl loss

[adeller]

This is a fantastic resource and a great place to turn when you need help, I recommend it often.

I started a SLAM process on July 16. My CYA was at 0 (another post). I added enough powder to bring the CYA to 40 and confirmed with multiple tests. I have been in continuous SLAM mode since July 16th (10 days). I am keeping the Cl at 19 or higher, as indicated by PoolMath for CYA of 40. I have read the SLAM process multiple times and am familiar with the concept, keep the Cl at or above SLAM level until the three criteria are met. So far for the OCLT I am missing 2 of the three criteria, at least the water is clear.

My pump is a variable speed, so it is running 21 hours at 25% and 3 hours at 75% except when I turn it up for Cl additions and testing. My routine has been:

First thing in the morning at 7 am: Run the pump on high, test - add Cl to get about 25
When I get home (6-7 pm): Run the pump on high, test, add Cl to get about 25
Test at about 9 pm to confirm the Cl level before going to bed.
Rinse, repeat.

The Cl usually tests at about 16-19 at the end of the day.

The problem is that the CL consumption is getting worse. Last week, I was losing 1 -1.5 ppm overnight, but not passing the CC test (1 - 1.5 ppm). Now, for the last 2 nights, I have lost 6 ppm each night. I also lose about 6 ppm over the course of the day as well (7 am to 6 pm). The CC are staying at between 1.0 and 1.5.

Nothing unusual is going on in the pool, the skimmer baskets are empty (no dead rats, been there, done that). My only guess is that I need to raise the CL higher, like to mustard level for a while and try that. Is this a Cl resistant strain, mutant algae, or (more likely) am I missing something? Or does it sometimes just take this long, and this much bleach? Thoughts?

Test results:

Cl: 19-25
CC: 1 - 1.5
pH: Unknown (was 7.2 at the start)
CYA: 40
CH: 350
TA: 80
Temp: 84 (finally!)

-Art

 

[Richard320]

Very often people in your situation discover an algae breeding ground behind the pool light or beneath ladder rungs or inside ladder poles. Check that. And maybe leave the SWG on as well and really fry whatever is growing in the pool.

 

[GreatCanadian]

When performing the OCLT did you make sure the SWG was OFF during the night?

 

[adeller]

When performing the OCLT did you make sure the SWG was OFF during the night?

Actually, the SWG has been off the entire time, at the suggestion of duraleigh.

- - - Updated - - -

Very often people in your situation discover an algae breeding ground behind the pool light or beneath ladder rungs or inside ladder poles. Check that. And maybe leave the SWG on as well and really fry whatever is growing in the pool.

Ok, the only places that could be are behind the lights and in the autofill bucket.

The autofill has been off (the backflow preventer got frozen this past winter) and I dosed the bucket several times directly with bleach.

I have Savi (?) LED lights, the small diameter ones. Can those be unscrewed from their mountings? (while immersed?)

 

[adeller]

OK, so tested this morning. I added Cl to 28ppm last night.
Back to 22 this morning with 1.5 CC. Basically I seem to be making no progress at all. 11 day in continuous SLAM, no progress.
I tested CYA again, just to make sure and it is testing a consistent 40.

 

[woodyp]

Which test kit are you using?

 

[adeller]

which test kit are you using?

tf100

 

[timerguy]

Hope you got the XL option. You may need it--SOON!

 

[adeller]

So I am now 12+ days into this SLAM with no signs of improvement whatsoever. Is it possible it just takes this long? It seems like a really long time. I have run this process before when the need was indicated and it usually clears up and holds Cl within a few days. How do I get off this merry-go-round. It is consuming at least 1-2 large bottles of bleach a day. I could put the SWG back online, but I know that raises the pH, and I have no idea where the pH is currently since testing above 10 ppm Cl if inaccurate, correct? My salt is also climbing like crazy with all of the bleach.

So far I have eliminated the autofill bucket as a source, it has been inactive for months and was stagnant. I flushed it periodically and added bleach occasionally. With the last vacuum I did I completely emptied it and flushed it out so it is filled with fresh water from the pool. I have brushed and vacuumed repeatedly, and brushed, and brushed. I have run the waterfall to purge that as well. There is always some small amount of stuff from the trees, but that has never caused problems like this. We are in our third season with the pool and have never experienced anything this bad.

The only thing suggested above that is left is to look at the lights. With the small SAVI LED lights, can I remove the covers while they are submerged without damaging the light? If I do, won't I then flood the tube with water that will then become stagnant again? Is it possible that contamination from here can continuously consume that much Cl over this long of a time.

Would raising the Cl to something insane, like 30-40 maybe finally burn this out?

Other than some small stains from leaves from the trees that were left still for too long in the past, the bottom looks clean. The water is clear. There are no obvious signs of anything wrong.

I have checked and double checked what I do know. I have run tests, and re-run them to be sure. I have been using the TF-100 (great kit ) for almost three years and am confident in the results.

 

[woodyp]

Couple of Murphys Law things to look at. Are you sure you are using Pool Math Correctly? Are you sure you are punching in the correct strength percentage of bleach you are using? Are your pool gallons known to be correct? What is the date code on the bottles of the bleach you are using? How is it being stored?

 

[adeller]

Couple of Murphys Law things to look at. Are you sure you are using Pool Math Correctly? Are you sure you are punching in the correct strength percentage of bleach you are using? Are your pool gallons known to be correct? What is the date code on the bottles of the bleach you are using? How is it being stored?

Good thoughts and worth checking again:

I have tested and tested again. By calculation and confirmed by testing CYA is 40. PoolMath shows a Shock value of 16. Mustard shock of 24 (I am reading that correctly, right?). Been running at 19+, just add normal engineering factor of safety
The bleach is all fresh (it comes in and goes so quickly now, I buy 6-8 bottles at a time and it doesn't stay around more that 3 or 4 days. I store it in the garage. I have calculated the amount of Cl rise I should get with one bottle of 6% 140 oz (I'll have to check the actual size, but been using the same brand/size for a while) and it is 6 based on 14k Gal. With actual testing I get 6. So regardless of how old or concentrated the bleach, I am testing the actual Cl rise that I am getting.

Even still, when I perform the OCLT, I test to get an initial value, add the calculated amount, stir, wait at least an hour and test again to get an actual value to start the test. Expected values are always very close to the calculated ones, giving me some confidence that at least my calibration is close.

I have backed up and tweaked my Gal estimate over time by using testing values of adding chemicals, (calculate value change for a known amount, test the results) Not just bleach, because I realize that the concentrations can be off, but with other chemicals as well, like CYA. The value I settled at is 14k gal, I little shy of the PB's estimate (no suprise, right?)

 

[adeller]

So, Day 19 of the SLAM. Still no let-up in the Cl loss and CC running pretty consistently at 1.5 (hit a high of 2.5 a few days ago). No improvement. No obvious signs of algae anywhere. Vacuumed the pool again this weekend and changed out the filter carts. No improvement there either.

So, the only place I haven't checked is the lights. They are SAVI LED lights. They appear to be sealed and show no obvious signs of algae either. I haven't opened them for fear of flooding the tubes they are in. Do I need to have the water level down in order to open these up? Could algae hiding behind these really be responsible for a continuous 6 ppm Cl loss every night?

The only other thing that has changed was that I sealed the deck (or attempted to) with a product that didn't work . (Big name manufacturer, not Dupont) After a month or two it is peeling off the stone, mostly where contacted by pool water, obviously not salt water safe. I will re-do this with the Dupont stuff. Some residue was in the pool, hence the filter change referenced above. Could this be responsible? I thought this stuff, once dry would be inert. I cleaned thoroughly and changed cartridges (there was some in the carts, but not very much) to get all of it that I could get out of the pool, but it didn't seem to make a difference.

Any thoughts? I would have thought I would see some improvement by now.

 

[timerguy]

Fresh is a very subjective term that relies on when it was manufactured, not purchased. If you bought it from a dollar store, is likely not fresh. I don't think I've seen 6% bleach in walmart. Pretty much everything I've seen is the concentrated 8.25%. If you don't buy from a big box store that goes through stock every couple days eg walmart or target -and possibly others, it's a crapshoot whether you're truly buying "fresh" bleach or not

 

[RobbieH]

I've seen the SLAM process take over 3 weeks on multiple occasions. Has the water turned milky yet or is it still just green?

 

[adeller]

Fresh is a very subjective term that relies on when it was manufactured, not purchased. If you bought it from a dollar store, is likely not fresh. I don't think I've seen 6% bleach in walmart. Pretty much everything I've seen is the concentrated 8.25%. If you don't buy from a big box store that goes through stock every couple days eg walmart or target -and possibly others, it's a crapshoot whether you're truly buying "fresh" bleach or not

Good point. You are correct, it is 8.25%, and I get it from Wal-Mart. The stock turn-over should be pretty high. Even still I am testing before and after addition, so no matter what the actual strength, I know exactly what the results are. At least at night before I begin the OCLT. In any case the bleach has consistently given me the expected Cl rise every time.

- - - Updated - - -

I've seen the SLAM process take over 3 weeks on multiple occasions. Has the water turned milky yet or is it still just green?

Still perfectly crystal clear. Has been the whole time.

 

[kcindc]

How often is the PSI indicating that you have to clean your cartridges? I'm asking because some people think their pool is clear, but they filter enough medium that shows that a lot of organics being still being filtered out.

 

[timerguy]

So, most 8.25% bleach comes at 121 oz/jug. Also if your pool is half shallow and deep average depth would be 4.5 ft making your pool ~ 13700 gals so adding 121oz should come to just under 6ppm. So your 6 computation is pretty close. Bottom line: you need to patiently continue to continue until it passes all three of the end of slam tests. Wish you the best of luck!

 

[adeller]

How often is the PSI indicating that you have to clean your cartridges? I'm asking because some people think their pool is clear, but they filter enough medium that shows that a lot of organics being still being filtered out.

If I go purely by PSI, I can go 4-6 months. I did this one early because of the sealer I mentioned earlier, and just to eliminate anything in the cartridges as a possibility.

 

[adeller]

Ok, so here I am 23 days into the SLAM and seem to be going backwards. I am starting to think of turning it into a Coy pond or filling it in and making a bigger patio would be a better us of space, resources and preserve my sanity.

I dosed yesterday morning at 7 am to 21ppm. It was 12.5ppm (SWG runnung!) when I got home at 7:30 pm. Dosed it back up to a target of 21. With pump running tested an hour and a half later at 25ppm. It was the same (21) this morning at 7 am (SWG still running) so am still probably losing about 6 ppm overnight. The CC is actually worse than a couple of weeks ago. I am getting 1.5 + at each test. (one test was as high as 3, but the pump was on 25% and it was the end of the day, maybe a bad test)

The water, as always, is still clear. There is nothing showing on the surface of the pool (except some calcium stains :-( ) This weekend I will probably bite the bullet and remove the covers on the lights. After reading some other threads I have determined that these can be removed without fear of damaging the lights. It is just with everything I have read about people having trouble with the SAVI lights, if mine weren't broke I didn't want to "fix" them. I am about out of ideas at this point, this is the last thing left, except maybe a stakeout at night to catch some troll or garden gnome relieving himself in the pool every night.

Thanks for listening. Ideas welcome.

 

[coog61]

I'm curious, do you have an idea how much algae it would take to cause your issues?