SLAM - how much longer?

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badlemur

Bronze Supporter
Jul 6, 2023
13
Colorado
Pool Size
15000
Surface
Fiberglass
Chlorine
Liquid Chlorine
Just checking in to make sure I am doing this right. Came back from vacation on Sunday to algae/organic growth. My test kit refills were at the post office until the next day, so I dumped 6 bottles of bleach in to kick off the slam. When I got the mail the next morning my free chlorine was 65ppm. PH was 7.2, TA 160, cya 70. Pool is 15k gallons, fiberglass with an autocover. In the past week I’ve seen the algae turn white and scrubbed vacuumed away. Since Wednesday, the pool has been clean and clear (I also replaced my filter cartridges during this time). However, I continue to lose a significant amount of chlorine each night. My CYA has dropped to 50 over the course of the week, bringing my slam level to 20, down from 28. I’ve also been adding some acid and aerating to lower the TA a little while not dropping PH too far. As of Saturday AM, 7 days in, I’m at FC 13.5 in the morning, pH 7.2, TA 150 no CC, cya 50, clear pool. I’ve added enough bleach to get back up to 20, which has typically held throughout the day, then in the morning, I’m back to 13.5 or so. again, no CC, clear pool. Do I just need to grit this out and keep adding the bleach every morning until overnight fc loss is down to 1 or less? Or am I missing something.
 
Checked again six hours later. Scrubbed sides and floor and found FC down to 16, target FC is 20. Added requisite amount of bleach. Snapped some photos. No significant debris came up as a result of the scrub. Will check again this evening (4 more hours or so).
 

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badlemur said:
Checked again six hours later. Scrubbed sides and floor and found FC down to 16, target FC is 20. Added requisite amount of bleach. Snapped some photos. No significant debris came up as a result of the scrub. Will check again this evening (4 more hours or so).
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Hard to tell with the wind on the surface, but seems like just a touch of green haze to the water. More often testing/replacing should help.
 
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One other note- worry about lowering ta later. After slam.
The Ph test is invalid at fc levels above 10ppm.
Also, check & scrub every nook & cranny
If water can go there algae can hide there.
Auto cover (& pit)
Skimmers , drains, overflow lines, auto fill pot etc
 
I appreciate the note on CYA dropping so rapidly. We’ve had 100+ temps plus a large chlorine load which I believe has helped lower the CYA numbers. I think this growth started due to my CYA going to 0 a few weeks ago. (I was gone on vacation for two weeks and the intellichem ran out a few days before I got home)

Anyway. - it’s 6 hours since my last test. FC fell by 2. Propping it up again to 20 prior to going to bed.

Water does not have a green tinge. This breakout was not really green algae and more organic growthish. At this point, it is only on the slight end of cloudy - like minimally cloudy. Also I have a consistently small load of pill bugs jumping in to the pool. Not really sure how to prevent that. They live in the auto cover pit at the end of the pool and I give them semi regular pest treatments.
 
I'd double check the CYA level as this drop makes no sense. Chlorine has no effect on lowering the cya. For all you know the slam level isn't being reached thinking it's 50 when it may br 60 or 70.
 
Again - totally agree with the CYA dropping so fast being irregular. I have tested it almost every day since starting the slam. Maybe I read the test wrong early on. But it has been consistently at 50 for the last 4 days.

In other news, passed the overnight free chlorine loss test with a drop of only .5 FC and no ccs after 10 overnight hours. I’m going to maintain slam level until tomorrow morning while also giving the underside of the cover a good brush. Thanks to whoever suggested that.
 
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Just when I thought I had it covered:

Tested last night at 8pm and again this am at 9am to find a 3.5 FC loss. Added chlorine and tested again at 1pm for an additional 5 FC loss. I’m wondering if I set something loose after brushing the bottom of the cover yesterday and am now dealing with it. CYA still at 50. Slamming to 20.
 
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@Mdragger88 is doing the test in the dark necessary since I have an auto cover? It’s always closed, so it’s always dark in the pool. My last tests are always close to sundown or after.

So at 1:30 I got mad and put some extra chlorine in. Tested at 4:30 and had FC of 25.5, CC was .5. Went out at 7:30 and had 23.5 FC, CC of 1. Letting it drift down to slam level of 20 (I reran CYA today to confirm it was still at 50). Will test again when the sun is fully down after 9.

And here’s the problem: despite fighting this for the last 8 days, I’m leaving town Wednesday AM for 12 days. Typically, the intellichem with a 3 gallon reserve has no problem maintaining the pool water while I’m gone. But at my current rate of chlorine burn, I’m going to have a problem. I have friends that come by every few days, but I can’t ask them to come by much more often.

I’m fingers crossed that this will sort out, but this relapse has me worried. Hope is not a plan.
 
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badlemur said:
@Mdragger88 is doing the test in the dark necessary since I have an auto cover? It’s always closed, so it’s always dark in the pool. My last tests are always close to sundown or after.

So at 1:30 I got mad and put some extra chlorine in. Tested at 4:30 and had FC of 25.5, CC was .5. Went out at 7:30 and had 23.5 FC, CC of 1. Letting it drift down to slam level of 20 (I reran CYA today to confirm it was still at 50). Will test again when the sun is fully down after 9.

And here’s the problem: despite fighting this for the last 8 days, I’m leaving town Wednesday AM for 12 days. Typically, the intellichem with a 3 gallon reserve has no problem maintaining the pool water while I’m gone. But at my current rate of chlorine burn, I’m going to have a problem. I have friends that come by every few days, but I can’t ask them to come by much more often.

I’m fingers crossed that this will sort out, but this relapse has me worried. Hope is not a plan.
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Perhaps if I'm reading into this correctly the CC is due to the auto cover not letting it outgas. That's why it's recommended to leave the cover open or atleast it being open say 30 minutes before testing so it doesn't skew the CC,s.
 
Tested again this morning at 8:30, 11 hours after the last tests. 19.5 FC, 0CC. I was super careful with my drops and cleaned out the test vial before performing the test. Added 13oz bleach to bring FC back to 20. Will test again in 2-3 hours.
 
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Might have made it:

7:30 AM: 19.5 FC, 0CC

Part of my problem may have been doing my morning test too late. Headed out of town later, we’ll see what I’ve got when I return.
 
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