Where did my stablizer go?

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curlytop09

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Oct 12, 2013
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I recently added "stain wipe - ascorbic acid alternative" to remove iron staining on our gunite pool. Worked like a charm, stains gone within the hour.

I tested the water with my TF-100 test kit prior to adding stain removal and tested again 24 hours later. The first test showed that I had 40ppm cyanauric acid. The test 24 hours later, I had no cyanauric acid. Does the stain wipe interfere with the test method or is there a reaction with the stain wipe? I'm not sure what the stain wipe actually is, there is nothing on the package that specifically says what I added to the pool.

I did this same treatment last winter. I did not test the stabilizer level after adding but the following spring, as I was starting to get the pool ready for summer, I had no stabilizer. I went into that winter with stabilizer and came out with zero. I looked up info on that and assumed it was some type of degradation of the the acid over the winter. Now that it appears that I lost the 40 ppm overnight, I'm curious as to what I might be seeing.

Also, am I going to regret not adding algacide to the pool before doing the stain treatment? The water temps are in the 40s, I was thinking that algae wouldn't be a problem and I could work my chlorine levels back up before I had an issue. I have a 2 year no SLAM required record (since replastering pool) that I may ruin.

Thanks
 
With your water temperature in the 40's you don't need to worry about algae growing in it, you have plenty of time to get your chlorine / cya level correct before your pool gets warm enough for algae to start growing, in general algae growth nearly stops below 60 degrees F. As to the CYA it can be lost over winters due to certain types of bacterial degradation when FC levels are low, so do you know your CYA was correct before adding this product?
 
Thanks for reply. I'm not sure if 40 ppm is "correct" since the reading is somewhat subjective with the black dot visibility. But the sample was cloudy in the test tube for the first test so the range is somewhere between 30-40 ppm. In the second test, the sample was clear.

For both tests, I did add pool water to the sample bottle and place is warm water long enough to warm sample a bit. Then added the reagent. I recall from test instructions that this is the one test that can be temperature dependent.
 
Isaac-1 said:
With your water temperature in the 40's you don't need to worry about algae growing in it, you have plenty of time to get your chlorine / cya level correct before your pool gets warm enough for algae to start growing, in general algae growth nearly stops below 60 degrees F. As to the CYA it can be lost over winters due to certain types of bacterial degradation when FC levels are low, so do you know your CYA was correct before adding this product?
Click to expand...

regarding temperature affecting algae growth, these threads are from chem geek at http://www.troublefreepool.com/threa...and-cool-water:

chem geek
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Re: Algae and cool water
Figure 1 in this paper gives a rough idea of the maximal algae growth rates as a function of temperature. The generation time, which is how long it takes to double in population, is a little over 5 hours at 86º F but drops down to a little over 12 hours at 59º F. Algae can still grow even near freezing temps, but the growth rate is much slower (someone on The PoolForum saw algae slowly growing under their frozen-over pool!). Note that these numbers are maximums assuming ideal nutrients and sunlight. This link in Figure 3 shows growth rates are temperature-dependent in a very species-specific way.

In practice, when the water temp gets colder, the amount of light is also reduced as more days are cloudy and the sun is lower in the sky. This one-two punch significantly slows down algae growth rates. If one also covers the pool with an opaque cover, then that cuts down sunlight even more.

Of course, if there is any chlorine or algaecide (including borates) leftover in the pool, then that can inhibit algae growth as well.
AND>>>
Though the growth rate of algae slows down as water gets colder, the reaction of chlorine killing algae also slows down. So lowering the FC level too much could be risky. The main advantage of the cooler water, especially if the sun isn't on the pool due to clouds or a cover, is the lower daily FC usage. I'd keep the FC at whatever level you normally need to do to prevent algae. Though it's possible that at some cold water temperature the algae growth plummets, why take the chance that it doesn't?
 
Thanks for the help. Based on the links shared above, maybe my CYA was borderline measurable. We did have rain so any dilution could have helped me get to a point that CYA would not register. I'll put some tri-chlor pucks in to start building it back up. On the positive side, going into spring with low CYA buys me room for vacation so I can use the pucks while we are gone.
 
Absolutely! In the meantime, while you are trying to build-up CYA, watch FC closely as it's possible it may get burned quickly by the sun with little stabilizer protection. You definitely want to maintain your target levels as noted on the Pool School - Chlorine / CYA Chart. Best of luck, and let us know if you have any other concerns. Have a good day.
 
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