Trouble Raising Chlorine

KristaM78

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Jun 29, 2021
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Illinois
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No. As long as your FC is above the minimum level for your CYA, you are still killing algae. Just slower than if your FC is at SLAM level.
Ok. I was thinking about going and dumping bunch of chlorine in tonight but not retesting tonight. I know that I’ll have chlorine lost overnight and I won’t be able to measure it but since I’m anticipating having a loss anyway I think I’m better off hitting that target don’t you think?
 

mknauss

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We never recommend 'dumping bunch of chlorine'. We test and add what is necessary to achieve the level the pool water needs.
 

KristaM78

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Jun 29, 2021
56
Illinois
Pool Size
11200
Surface
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Chlorine
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Pentair Intellichlor IC-40
We never recommend 'dumping bunch of chlorine'. We test and add what is necessary to achieve the level the pool water needs.
I get that. I didn’t really mean that. I meant more to bring it back up to target. But I don’t want to test again this evening. I’m leaving it be.
 
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Mdragger88

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Jun 1, 2018
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Your bleach may no longer be the strength it states . This can be due to old stock or product that has been stored improperly (like outside in the sun).
Tomorrow try this … test - then add the amount called for by poolmath & test again about 30 minutes later. You can play around w/ effects of adding to determine what percentage you really have based on the amount of fc you got from your dose. Adjust future doses with that batch accordingly.
Checking date codes when purchasing can help avoid the old stock situation-
 

KristaM78

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Jun 29, 2021
56
Illinois
Pool Size
11200
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Pentair Intellichlor IC-40
Well, I still have seen no evidence of dead algae in my pool. I’ve been brushing and vacuuming and I’m now im almost 2 weeks into the slam process. Over the weekend I did identify gunk on the back of my skimmer door and soaked everything in bleach. Currently I have my pump basket soaking in bleach but I still can’t figure out why I’m not holding chlorine when I see zero evidence of algae. At the very least I would think that I would being seeing dead algae.
 

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Texas Splash

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Your thread is getting quite long, and a 2 week SLAM is a long time for a pool with relatively clear water. Refresh my memory please, do you have a light with a niche? If so, have you removed it? Sorry if that was addressed earlier. I don't think you have anything else in the pool itself correct? Lastly, after discovering the stuff in the skimmer and cleaning it, have you performed another Overnight Chlorine Loss Test?
 

KristaM78

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Jun 29, 2021
56
Illinois
Pool Size
11200
Surface
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Chlorine
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Pentair Intellichlor IC-40
I do not have a light niche. I did notice my OCLT was better this morning ; only 1.5 ppm loss. I saw quite a bit of loss today During the day, but I’m hoping that was sunlight. Hoping tomorrow morning shows me little loss. Yes, this thread is huge. I am exhausted lol. Pool will close on Monday day and I can’t wait!! Praying all will be ok!
 

KristaM78

Well-known member
Jun 29, 2021
56
Illinois
Pool Size
11200
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Ok. Here is where I am at, and a question. Since I am not a chemist and I try to measure to the line perfectly…and the amount of powder added to the test is not actually measured, isn’t there a margin of error here? I test 19.5 this Am, then immediately repeated and got 18.5. Last night I was 21.5. I try to put the bottom of the water bubble right on the line but it’s not usually perfect.
 

Texas Splash

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When filling the chlorine only tube, the water should line-up with the 10 ml marking. Unlike the OTO block viewer, there shouldn't be an obvious curve at the waterline sample, but if there is, just go with the bottom point of the curve. But in the grand scheme of things, it shouldn't matter that much. Same with the power - one generous scoop of powder for a 10 ml water sample.

The fact that you noticed a 1 ppm difference in test separate tests performed at about the same time, says something is inconsistent with the testing. I'm assuming the water sample was from the same batch, so perhaps there was a counting error? It gets monotonous counting so many drops of about 40 or so. :crazy:

But let's give you the benefit of the doubt and say your morning FC was 19.5. You started at 21.5, so that's still a 2 ppm drop in darkness. At this stage it really doesn't make sense. I know you're exhausted from the SLAM Process, and you close Monday. So here's what I would suggest:

With pool completely void of any toys or anything that could visibly hold algae somewhere (no niche, drain cover, etc), do a final FC increase to Mustard Algae level of 29 (based on a current CYA as the guide). Just add enough chlorine to get to 29 and call it done - no swimming while that high. It will take a couple days for that FC to fall. By Monday the FC may still be slightly elevated, but should be below SLAM level and ready for closing. Take a well deserved break and relax until next year.

If out of curiosity you want to do another Overnight Chlorine Loss Test, wait until Sunday evening/Monday morning to try it. I'd be curious to see what you get.
 
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ccbill

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Jul 23, 2021
122
Atascadero, Ca
Pool Size
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Chlorine
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...The fact that you noticed a 1 ppm difference in test separate tests performed at about the same time, says something is inconsistent with the testing.
Keep in mind that Taylor says there can be a +/- 1 drop error for every ten drops. For high drop counts I try to make each drop the same by slowly squeezing a drop out and after it drops relaxing the bottle then do it again. Every once in a while I see a drop that is not like the others. It became much easier to focus on the drops when I got a SpeedStir.

Aim for consistency in your drops.
 
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KristaM78

Well-known member
Jun 29, 2021
56
Illinois
Pool Size
11200
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
When filling the chlorine only tube, the water should line-up with the 10 ml marking. Unlike the OTO block viewer, there shouldn't be an obvious curve at the waterline sample, but if there is, just go with the bottom point of the curve. But in the grand scheme of things, it shouldn't matter that much. Same with the power - one generous scoop of powder for a 10 ml water sample.

The fact that you noticed a 1 ppm difference in test separate tests performed at about the same time, says something is inconsistent with the testing. I'm assuming the water sample was from the same batch, so perhaps there was a counting error? It gets monotonous counting so many drops of about 40 or so. :crazy:

But let's give you the benefit of the doubt and say your morning FC was 19.5. You started at 21.5, so that's still a 2 ppm drop in darkness. At this stage it really doesn't make sense. I know you're exhausted from the SLAM Process, and you close Monday. So here's what I would suggest:

With pool completely void of any toys or anything that could visibly hold algae somewhere (no niche, drain cover, etc), do a final FC increase to Mustard Algae level of 29 (based on a current CYA as the guide). Just add enough chlorine to get to 29 and call it done - no swimming while that high. It will take a couple days for that FC to fall. By Monday the FC may still be slightly elevated, but should be below SLAM level and ready for closing. Take a well deserved break and relax until next year.

If out of curiosity you want to do another Overnight Chlorine Loss Test, wait until Sunday evening/Monday morning to try it. I'd be curious to see what you get.
Wait. So line up the top of the water or the bottom of the curve with the 10ml mark? I didn’t understand.
 

mknauss

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TFP Expert
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May 3, 2014
44,041
Laughlin, NV
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Pentair Intellichlor IC-40
Wait. So line up the top of the water or the bottom of the curve with the 10ml mark? I didn’t understand.
Fill the sample tube with pool water to the 10 ml mark. The top of the sample will be curved. This curve is called a meniscus. The bottom of the meniscus should be level with the 10 ml mark.
 

KristaM78

Well-known member
Jun 29, 2021
56
Illinois
Pool Size
11200
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
When filling the chlorine only tube, the water should line-up with the 10 ml marking. Unlike the OTO block viewer, there shouldn't be an obvious curve at the waterline sample, but if there is, just go with the bottom point of the curve. But in the grand scheme of things, it shouldn't matter that much. Same with the power - one generous scoop of powder for a 10 ml water sample.

The fact that you noticed a 1 ppm difference in test separate tests performed at about the same time, says something is inconsistent with the testing. I'm assuming the water sample was from the same batch, so perhaps there was a counting error? It gets monotonous counting so many drops of about 40 or so. :crazy:

But let's give you the benefit of the doubt and say your morning FC was 19.5. You started at 21.5, so that's still a 2 ppm drop in darkness. At this stage it really doesn't make sense. I know you're exhausted from the SLAM Process, and you close Monday. So here's what I would suggest:

With pool completely void of any toys or anything that could visibly hold algae somewhere (no niche, drain cover, etc), do a final FC increase to Mustard Algae level of 29 (based on a current CYA as the guide). Just add enough chlorine to get to 29 and call it done - no swimming while that high. It will take a couple days for that FC to fall. By Monday the FC may still be slightly elevated, but should be below SLAM level and ready for closing. Take a well deserved break and relax until next year.

If out of curiosity you want to do another Overnight Chlorine Loss Test, wait until Sunday evening/Monday morning to try it. I'd be curious to see what you
OK I feel like I am seeing some dark discoloration on the bottom side of my drains. I’ve been scrubbing them for days it’s really hard to reach underneath of there in the water is way too cold to get in the pool. But I feel like the discoloration is getting darker. Maybe that’s a good thing but I’m wondering if that is where the algae is. I was just getting ready to raise the chlorine to the mustard algae level that you suggested based on this do you think that’s a good idea.
 

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Texas Splash

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I feel like I am seeing some dark discoloration on the bottom side of my drains.
If you are I'm just not seeing it from my end. If it brushes off it's algae. If not, we'd have to look into that later. You're at a point now where it's time to prepare for Monday's closing.

Did we ever ask you if you are on a well? Any indications of iron in your local water?
 

KristaM78

Well-known member
Jun 29, 2021
56
Illinois
Pool Size
11200
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
If you are I'm just not seeing it from my end. If it brushes off it's algae. If not, we'd have to look into that later. You're at a point now where it's time to prepare for Monday's closing.

Did we ever ask you if you are on a well? Any indications of iron in your local water?
City water. It does not brush off. I’m working on the Slam of 29 and will let it be. Ty for all your help.
 
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