Can't complete my first SLAM?

[bad144]

A few weeks ago my aquapure stopped being able to generate enough FC (2ppm+), leaving the pool chlorine basically 0 or 0.5. Wound up replacing my aquapure cell but still couldn't keep up given a 100% production rate for 8 hours. I was used to just 20% production rate, as we keep the pool covered.

So I started a SLAM about a week ago but have been unable to complete the SLAM.
My CYA is about 65 so I was SLAMing with a target of 28ppm. Now my water looks clear but I still get a few fistfulls of what looks like dead algae forming at the bottom of the pool every few days. And just when my FC looks stable I fail overnight loss and read significant CC too. Any idea why this keeps oscillating?
I'm testing with taylor FAS-DPD, and for example, I get:

10/18 8am: 38 drops reagent for FC, 12 drops CC (19ppm FC, 6ppm CC)
added 2 gallons sodium hypochlorite 12.5%
10/18 3:30pm 78 drops reagent for FC, 0 drops CC (39ppm FC, 0ppm CC)
10/18 6pm 77 drops FC, 1 drop CC
10/19 7am 44 drops FC, 13 drops CC (22ppm FC, 6.5ppm CC)

Is there something wrong with my tests? Some of those CC counts are so high that I'm below the 10X rule for breakpoint chlorination, even though I'm above 40% of my CYA. Have I hit the "point of no return"? Yet my water looks clear...

I should add, my spillway trough is a bit of a plant-debris magnet, I had to
clean a bunch of leaves out of there during the SLAM, but now it's as clean as I can get it without pressure washing.

 

[Texas Splash]

Hello bad144 and welcome to TFP! . So you've been battling algae and managing your FC at 28 based on a CYA of 65 (rounded-up to 70). For your FC tests, if you are using the 10ml sample, you add-up the total drops and multiply by .5 - basically cut in half. Example: 60 drops would equate to an FC of 30. What I would suggest for you is (for now) use a 5ml sample and count each drop as ONE and that total number is your FC. Example: 30 drops = FC of 30. That should save you some reagent in the early part of the SLAM. Just about when you think you are close to passing, then go back to the 10ML sample for accuracy during the OCLT.

CC testing - Add 5 drops of R-0003 and swirl to mix. If the sample remains clear, your CC level is zero. If the sample turns pink again, add R-0871 one drop at a time, swirling constantly and counting the number of drops as you go. Continue adding drops until the color changes to clear. The pink color may become extremely faint before it goes away. Make sure that the sample goes completely clear. 8. Multiply the number of drops by 0.5 to get your CC level.

During your SLAM, you're SWG is off correct? You're using just regular liquid bleach? Continue the scrubbing, cleaning filter, etc? Follow everything listed on the SLAM page (link in my sig below) and will work. The key for many is finding that one spot in the pool where algae seems to hide (ladders, behind the light niche, etc). You may be onto something with that trough as well.

You can pass the 3 SLAM criteria. Continue to maintain the FC level and let the bleach do its job. It will work. Feel free to post back if you have any questions.

 

[pabeader]

Like Texas says; it sounds to me like you have some algae hiding somewhere. Remove any lights, check ladder, steps, spillways, returns, basically, anywhere that algae can hide.
Also, I don't see where you mention brushing the sides and bottom of your pool. You are doing that, right? At least once a day if not more often?
Your pump/filter is on 24/7, correct?
And finally, make sure you are testing and adding as often as you can. A minimum of 4 times a day. At the beginning of a SLAM it's better to do like every 1-2 hours. Until the FC starts to hold. Then you can stretch out the time between tests.

 

[Catanzaro]

10/18 8am: 38 drops reagent for FC, 12 drops CC (19ppm FC, 6ppm CC) added 2 gallons sodium hypochlorite 12.5% 10/18 3:30pm 78 drops reagent for FC, 0 drops CC (39ppm FC, 0ppm CC) 10/18 6pm 77 drops FC, 1 drop CC 10/19 7am 44 drops FC, 13 drops CC (22ppm FC, 6.5ppm CC)

If you are seeing fistful of what appears to be dead algae on the bottom of the floor, then the SLAM is not complete. Are you brushing the walls daily? Your testing CC numbers are all over the place. A friend of mine was having the same issue with the CC testing, and we determined that he was not holding the bottle correctly, allowing the drop to fall off the tip. By no means am I indicating testing error at this time, but it seems odd to have CC readings of 6, 0, .5 and then 6.5 in a short period of time. Combined Chlorine readings will drop and stay low for a while until you pass all 3 tests. Please keep us posted.

 

[bad144]

Thank you, yes I was using 10ml samples for my tests, switching to 5ml sounds like a good idea. With 5ml I'd still add 5 drops of R-0003 for the CC test in that case, right? I tested this way with 5 drops r0003, and at 5pm got:
33 drops FC 3 drops CC (so 33ppm FC 3ppm CC). Pool looks clear.
This strikes me as pretty strange numbers given that I had less FC than this 10 hours earlier and I have not added chlorine today at all.

Yes, my SWG generator is off. I'm using Hasa sani-clor (sodium hypochlorite). It's not stabilized so I think I should be good.

I had been letting my pool guy do the scrubbing, so he may not have done enough; he has missed some days as well. He did have to clean out the filters as the pressure had gone up. I can tell pretty readily when the pressure is down as my spillway won't flow with my intelliflo on low rpm.

Yes, been running the filter pump 24/7 but only maybe 3 hours on the spillway per day (it turns over in 1 hour or less).

I've also drained the spillway trough twice now to clean it.

So my symptoms are some algae hiding out somewhere? I though the shock level chlorine would kill it regardless.

 

[pabeader]

It can't get into places where the water doesn't move. So for example, in the area behind the light. That algae can develop a real strong biofilm that protects it from the chlorine. A little will get killed and leak out and show up as CCs.

 

[bad144]

If you are seeing fistful of what appears to be dead algae on the bottom of the floor, then the SLAM is not complete. Are you brushing the walls daily? Your testing CC numbers are all over the place. A friend of mine was having the same issue with the CC testing, and we determined that he was not holding the bottle correctly, allowing the drop to fall off the tip. By no means am I indicating testing error at this time, but it seems odd to have CC readings of 6, 0, .5 and then 6.5 in a short period of time. Combined Chlorine readings will drop and stay low for a while until you pass all 3 tests. Please keep us posted.

Hmm, I haven't been careful to hold the bottle completely vertical, I'm been maybe 20 degrees off, squeezing gently to get the drops to come out. So this gives me over-sized drops some of the time? Argh.

 

[bad144]

It can't get into places where the water doesn't move. So for example, in the area behind the light. That algae can develop a real strong biofilm that protects it from the chlorine. A little will get killed and leak out and show up as CCs.

My lights are flush at the bottom of the pool I can't really work with them without some free-diving practice. I had them leak tested last year and they passed so hopefully if water can't get in algae isn't passing through either?

 

[pabeader]

Fingers crossed on that one

 

[Catanzaro]

33 drops FC 3 drops CC (so 33ppm FC 3ppm CC). Pool looks clear.
This strikes me as pretty strange numbers given that I had less FC than this 10 hours earlier and I have not added chlorine today at all.

At these levels, testing error probability increases:


TESTING ERROR ON CALCIUM HARDNESS – THREAD
Calcium Hardness High - Page 2

5 SOURCES OF ERROR IN WATER TESTING
https://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=79

TWO WAYS TO IMPROVE DROP-TEST ACCURACY
https://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=6

UNDERSTANDING CALCIUM HARDNESS
https://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=70

RECOGNIZING A COMPROMISED REAGENT
https://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=2

This is a good one from Chem-Geek regarding possibilities of testing errors:

Numbers ok but water has a hint of cloudiness - Page 6

Post # 114

 

[bad144]

So my last 4 tests with 5ml samples were
10/19 5pm 33 FC 3 CC
10/20 7am 34 FC 0 CC
10/20 1:30pm 34 FC 1 CC
10/20 5:30pm 30 FC 0 CC
So looks like I could be "done" if I don't lose overnight tonight, right?
Seems like extra cleaning and being full vertical for the drop tests has made the difference.

Now when I'm done, should I be able to lower FC to "safe" levels with a day or so of sunlight exposure?
My CYA is probably down 10% with water loss from my spillway, to around 60.

 

[pabeader]

How clear is your pool?

 

[bad144]

How clear is your pool?

Looks clear to me. I could count the vent slots on the drain at the bottom, 6' down (if my eyesight was good enough).
There's staining on the gunite, but it doesn't scrape off; has always been there since it was built and apparently acid washed too soon after construction.
Latest dead algae globs at the bottom I skimmed up Mon. morning.

 

[pabeader]

Sounds pretty clear to me.

 

[kimkats]

So here is what I want you to do.......................get a toothbrush for your pool. Run it all around your skimmer box inside and out. Also run it around your returns. Do your best to run it around your lights as much as possible. Do any steps or ladders and the underside of anything you can get to.

There is a tiny bit of algae hiding and it is up to you to find it. Happy hunting!

Kim

 

[Catanzaro]

So looks like I could be "done" if I don't lose overnight tonight, right?
Seems like extra cleaning and being full vertical for the drop tests has made the difference.

Take your time with the testing to ensure it is as accurate as possible. I would suggest performing the overnight no longer than an 8 hour time frame. If for some strange reason you are having trouble with the overnight test, please go back up and read post # 114 on the link, long explanation about the testing so you can get through the overnight.

Now when I'm done, should I be able to lower FC to "safe" levels with a day or so of sunlight exposure?
My CYA is probably down 10% with water loss from my spillway, to around 60.

The FC will come down slowly to near your minimum. This will happen over several days, not overnight. Once this happens, you can start dosing your pool with the right amount of liquid chlorine daily. Regarding "safe levels", it is always safe to swim up to shock level. You are considered safe at this point. The higher levels of chlorine will not do anything to you or the pool over the next week or so until the levels come down.

 

[bad144]

Take your time with the testing to ensure it is as accurate as possible. I would suggest performing the overnight no longer than an 8 hour time frame. If for some strange reason you are having trouble with the overnight test, please go back up and read post # 114 on the link, long explanation about the testing so you can get through the overnight.

But I'm supposed to use daylight light for the fas-dpd color test per taylor instructions, so I've been doing it at sunrise&sunset. If I only test 8 hours I'll have to test indoors (3000k temperature). Seems like testing indoors shouldn't be a problem, but a bit conflicting instructions there. BTW, my overnight FC stayed at 30ppm and CC went from 0 to 1ppm.

 

[kimkats]

I test inside. I turn on the bright light over my stove. I hold a white plate behind the tubes and put it back and forth until I can see the color match. It works much better for me.

Kim

 

[pabeader]

We treat most manufactures instructions as 'suggestions'. If you want to know the best way, I would ask here first. Lots of folks who have been doing this stuff for years and are willing to pass along everything they've learned.

 

[PAGirl]

But I'm supposed to use daylight light for the fas-dpd color test per taylor instructions, so I've been doing it at sunrise&sunset. If I only test 8 hours I'll have to test indoors (3000k temperature). Seems like testing indoors shouldn't be a problem, but a bit conflicting instructions there. BTW, my overnight FC stayed at 30ppm and CC went from 0 to 1ppm.

Was 30 your starting point?