Loosing chlorine again..

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Azmp1

Azmp1

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LifeTime Supporter
Jul 20, 2012
311
Maryland
So I've been doing great for good 2 months or so since my last bout with algae and SLAMing. Keeping the FC levels right around 5-6ppm consistently. All before this last weekend. Quite a bit of pool use with quite a few adult and kids. I test on Sunday and get 1ppm. So I shock with 12% bleach and set SWG on 12 hour boost. Next day I check and I'm still at 1ppm, however CC is reading consistently at 0. So I'm thinking maybe I'm low on salt again, so add salt SWG on 100, test, FC as at 1.5ppm, CC still 0. And I also notice a lot of particles in the water otherwise water is fine. So I shock with 3 gallons of 12% bleach again, test in the evening, FC 5ppm, CC 0. So I figure I do an OCLT just to be sure, turned off SWG, and in the morning (today) sure enough down to 3ppm, CC remains at 0. Pool is covered all day, just got home measured FC down to 2.5ppm, CC =0. I and I definitely still see particles in the water, though the water is chill crystal clear.
So what really throws me off here is that my CC is staying at 0... My pervious bouts with algae was always high CC. But I suppose it doesn't matter since I'm loosing chlorine at the rate I shouldn't.. And what's the deal with the particles?
I'm planning to SLAM tomorrow, but wanted to double check with you guys first.
Everything is is norm
pH 7.6
TA 80
Ch 240
Cya 75
salt 3800


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Well, the heavy swimmers load and sudden FC drop seems to have bitten you. :( Don't get too wrapped on the CC and algae since you can have algae without CC. It all depends on the condition of the "trash" chlorine as it's being eliminated and oxidized. Anyways, the OCLT is a pretty good indication you need to SLAM. I do like t point-out to make sure during the OCLT:
- The SWG was turned-off
- You increased your FC level to anywhere between 10 FC and SLAM FC to test overnight
Those two things are quite important for the OCLT. As for the particles, it may not be directly related to the drop in FC. Not sure yet. It may be something just from the heavy swimmers load, or may require additional filtering once you control the FC loss. Maybe others will have an idea as well. :)
 
You are riding too close to the edge of the minimum chlorine level which is allowing algae to grow and consume your chlorine. CYA of 80 (always round up to the next 10) has min FC of 4 and target of 6. It is not unreasonable to lose 2 ppm of FC in a hot sunny afternoon with a lot of people in the pool.

CYA is 70 in my saltwater pool, it is very hot and sunny and we swim every day and a lot on the weekend. I keep my FC around 8 or 9 during the week and when we are going to have extra people on the weekend or plan to be in the pool all day I will add bleach to raise FC up to 10 or a tad higher in the morning. Then I will sometimes test and add again mid-afternoon if there are younger kids swimming. I raise it back to 10 when we finish swimming and if it dropped 3 ppm or so I will test again in a few hours to make sure the FC held at at least 7 or 8.
 
Thanks guys... Yes, heavy swimmer load and 90+ degree water... I thought I was good though, I actually udjusted my SWG down to 10% (since the pool is always covered when not in use so I don't get much of sunlight chlorine lose, was riding that for a while keeping it at ~5ppm.. And all it took is one slip. Well, will SLAM tomorrow. had to get it up 32ppm last time...


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Azmp1 said:
Thanks guys... Yes, heavy swimmer load and 90+ degree water... I thought I was good though, I actually udjusted my SWG down to 10% (since the pool is always covered when not in use so I don't get much of sunlight chlorine lose, was riding that for a while keeping it at ~5ppm.. And all it took is one slip. Well, will SLAM tomorrow. had to get it up 32ppm last time...


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Click to expand...

We did a swim-n-slam a month ago, with FC of 70 I kept FC at 25-28 and we swam every day for a week and a half. Much easier and cooler to brush IN the pool! :paddle:
 
Lower the PH to 7.2 before the slam and if will be fine. It is safe to swim up shock level for your CYA. My kids even opened their eyes and didn't notice a thing. I made them wear goggles anyway though.
 
Well, maybe I won't need to SLAM after all... last night added 32 oz of m. acid to get the pH down and figured I will SLAM in the morning. tested this morning and had about .5ppm lose over night (SWG off). so off to work, in the meant time I figure I'll get SWG back on, won't hurt... get home just now, test and FC is up to 4.5ppm!! first time I'm actually increasing chlorine without dumping shock in just about a week!!
So, im adding another 4 gl of 12% of liquid shock, to get the levels to 10ppm and will do another OCLT overnight. Hopefully bullet dodged and another lesson learned not to cut too close on the FC levels!!
 

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So i still lost about 1.5ppm overnight, so i figured I'll go ahead and SLAM anyway, so before I do, I go and check CYA and there is none!! I could see the dot with tube filled all the way to the top! And it was up to around 80ppm just few weeks ago when I converted to salt.. It makes sense for it to start going down since I no longer use trichlore since converting to salt and I do add about an inch of water a week.. So I'm pretty concerned at this point. Could it be that it got converted to ammonia? How do I test for that? Or what else could it be?


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you can get a kit at a pet store that has fish stuff. also, if you put bleach in and it seems to disappear like magic. That's a pretty good indicator.

- - - Updated - - -

Under normal conditions. CYA does not go away on it's own. Having to add water due to evaporation would not cause CYA loss. If you think about it, all that changes when water evaporates is the water goes down. Everything that was in the pool is still there, just more concentrated. As soon as you add water back into the pool, the concentration goes back to the same it was before the evaporation.
 
Azmp1, it would appear strange that your CYA went from 75 to nothing. To rule-out anything odd, simply do the following:
1. Begin a SLAM and dose FC up to SLAM level. Do not add additional CYA at this point.
2. Retest FC at 10-minute intervals.
a. If FC loss is greater than 50%, add FC to bring back up to SLAM level and continue retesting FC @ 10-minute intervals.
b. IF FC loss is 50% or less, add FC to bring back up to SLAM level. Go to Step 3.
3. If CYA is below 30 ppm, add enough CYA to bring level up to 30 ppm.
4. Continue SLAM as directed in the SLAM article until the SLAM Criteria of Done are met. Test as directed in the SLAM article - no longer need to test FC at 10 minute increments at this point.

This should get you back on-track, but follow those directions carefully. :)
 
Thank you guys. Texas, thank you for the instructions, one question I have is, at this point, since I no longer really know what my CYA level is, how do I know to what I need to bring the chlorine level for the SLAM? Do I get up to the level based on 0 CYA, or do I still SLAM like I did before with getting the chlorine levels high as if I had CYA at 80?


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Base the slam level on 0 CYA if that is your test result. Do the 10 minute test cycle and see how much chlorine you loose in that amount of time. Test FC, dose to slam level, wait 10 minutes with the pump running, test again.

Speaking of pump running, was yours running at least 30 minutes prior to pulling the sample for the CYA test?
 
Thinking about this... Few more questions... So assuming my CYA is at 0, based on the table, my SLAM level is 10ppm, correct? But... As I will be doing this tomorrow afternoon (and looks like it will be nice sunny weather), wouldn't the results get skewed because of the sunlight lose?


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Sunlight won't burn off 10ppm of chlorine in 10 minutes, even with 0 CYA. It is very important that you don't wait longer than 10 minutes to pull your sample for testing. If you end up waiting an hour to pull the sample the test won't be valid for what we are looking for, rapid chlorine loss.
 

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