Chlorine Demand

[ragart]

When I opened my pool, I shocked it with approximately 10ppm free chlorine. The chlorine immediately became combined chlorine (test and foul smell resulted). I drained some water out and refilled and then shocked it with 30ppm free chlorine. The same issue (combined chlorine and smell) resulted. I again drained some water and refilled. Tested at 5ppm Total Chlorine. Near zero Free Chlorine. I added 5 pounds of potassium monopersulfate shock. I then added sodium thiosulfate to eliminate the combined chlorine. I added another 5 pounds of potassium monopersulfate shock. The pool water has been crystal clear since the day after my opening and initial shocking.

These are my readings:
22,000 salt pool (salt generator not currently operating). Vinyl liner.
0 FC
0 TC
0 Phosphates
0 CYA
5-10 Nitrates
0.15 Nitrites
7.2 Ph
100 Alkalinity
Water temperature 53 degrees

Any help as to next steps to as to not recreate the chloramine creation process I began at opening, would be appreciated.

 

[DiverGirl1972]

It seems like you're losing all of your chlorine because you have no CYA in your water and it's all getting burned off. You'll want to get that up to 30 - 40 or so and your FC should start holding better. All you should need is CYA and chlorine....stay away from non-chlorine shocks. They do more harm than good.

 

[mknauss]

I suggest you read about TFPC. None of your processes make any sense to what your goal is. Also, those are pool store tests and we rely on pool owner water chemistry test results using a proper test kit.
ABCs of Pool Water Chemistry
SLAM Process

What is TFPC?

We believe any pool owner can achieve and maintain safe, crystal clear pool water, by using the science-based, Trouble Free Pool Care (TFPC) methodology.

www.troublefreepool.com

Test Kits Compared

 

[YippeeSkippy]

 

[ragart]

I suggest you read about TFPC. None of your processes make any sense to what your goal is. Also, those are pool store tests and we rely on pool owner water chemistry test results using a proper test kit.
ABCs of Pool Water Chemistry
SLAM Process

What is TFPC?

We believe any pool owner can achieve and maintain safe, crystal clear pool water, by using the science-based, Trouble Free Pool Care (TFPC) methodology.

www.troublefreepool.com

Test Kits Compared

Thanks to all. I solved the issue. It was not a CYA issue because the shocking was being done at night. Good advice about the non-chlorine shock.

I suggest you read about TFPC. None of your processes make any sense to what your goal is. Also, those are pool store tests and we rely on pool owner water chemistry test results using a proper test kit.
ABCs of Pool Water Chemistry
SLAM Process

What is TFPC?

We believe any pool owner can achieve and maintain safe, crystal clear pool water, by using the science-based, Trouble Free Pool Care (TFPC) methodology.

www.troublefreepool.com

Test Kits Compared

Thanks! Problem solved. All tests were done at home.

 

[Donldson]

The problem was solved because it was ammonia. Enough chlorine fixes that problem eventually.

Just FIY: the MPS and chlorine neutralizer did nothing to solve this problem. You should really consider not brushing off those links. Your post shows a lot of wasted money and time that could have been prevented. We can help prevent the next one, if you wanted.

 

[ragart]

The problem was solved because it was ammonia. Enough chlorine fixes that problem eventually.

Just FIY: the MPS and chlorine neutralizer did nothing to solve this problem. You should really consider not brushing off those links. Your post shows a lot of wasted money and time that could have been prevented. We can help prevent the next one, if you wanted.

Absolutely right. Probably about $50 of wasted chemicals. I was hoping the ammonia would be reflected in the nitrate test, but it wasn’t. As it was I simply wasn’t using enough chlorine. It took about 40-45ppm to break through. As it was, the 30ppm I tried initially did nothing but create combined chlorine. Thanks for weighing in. Much appreciated.

 

[ragart]

It seems like you're losing all of your chlorine because you have no CYA in your water and it's all getting burned off. You'll want to get that up to 30 - 40 or so and your FC should start holding better. All you should need is CYA and chlorine....stay away from non-chlorine shocks. They do more harm than good.

Could you elaborate on your "harm" reference respecting chlorine free shock? I have some left over and I am wondering whether I should use it or toss it. What exactly is the harm side of the equation? Thanks!

 

[mknauss]

MPS tests as CC for some time. It creates confusion and does not address the problem, algae.

 

[ragart]

Thank you! So after I super shocked my pool with liquid chlorine earlier in the week (45ppm), everything was fine. It was holding FC well over several days and the CC went to zero. Yesterday we had 4 swimmers in the pool and a TON of pool floats. The FC was gobbled up quickly. I added around 7ppm over the course of the day and it would hold for a while but was consumed way too quickly. At night I shocked it with 5ppm chlorine. The chlorine held for several hours until I went to bed, but when I got up both FC and TC readings were close to zero. CYA Level is about 45. I was not having this problem until yesterday when the swimming and pool floats started. Any insights? The FC I was using was liquid chlorine I purchased in March, so it might have been leftover from last pool season and therefore old. Would older chlorine give off symptoms like this? Much appreciated.

 

[mknauss]

Not sure what process you are following but it is not TFPC. Up to you.
You need to follow the SLAM Process

 

[ragart]

Not sure what process you are following but it is not TFPC. Up to you.
You need to follow the SLAM Process

So the hypothesis is that there is algae in the pool that is just not visible to the eye? Does this make sense that everything would be fine for 3-4 days then only bad when swimming started? Wouldn't that be forming combined chlorine then? Why is my combined chlorine basically zero? Thanks!

 

[mknauss]

You can have algae and 0 CC. CC is created from chlorine consuming ammonia based compounds. Algae does not always create CC.

You definitely can have algae in the water you cannot see. It can also be in light niches, skimmer throats, weir doors, etc.

 

[ragart]

Thank you!

 

[YippeeSkippy]

FC is used up by more than just algae. Five swimmers bring in with them sweat, make up, body oils and lotions, microscopic fecal material, spilled beer.... all of which use up your chlorine. The trick is to have enough FC in the pool at all times to prevent the pool test going to zero.

Maddie

 

[ragart]

FC is used up by more than just algae. Five swimmers bring in with them sweat, make up, body oils and lotions, microscopic fecal material, spilled beer.... all of which use up your chlorine. The trick is to have enough FC in the pool at all times to prevent the pool test going to zero.

Maddie

Thank you! After the most recent time it went to zero, I added some fresh recently purchased liquid chlorine. The chlorine held well through a long swimming session and overnight and into this afternoon. Seems like it was just a case of bad/expired chlorine that wasn’t up to the task!