Adjustment for cyanuric acid.

What is floc, clarifier, stabilizer, cyanuric acid,
algaecide, brightener, dichlor, sodium hypo,
sodium bisulfate, ....??
Leon
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Adjustment for cyanuric acid.

Postby Leon » Tue 12 Sep, 2006 15:21

I use a Taylor (HIGH) test kit. The booklet that comes with the kit recommends adjustments to the alkalinity reading for high cyanuric acid concentrations. My pool has a cyanuric acid concentration of 100 which I know is high but it's been that way for a long, long time and I can't get it down. That, however, is not the question. Taylor says for a ph of 7.4 and a cyanuric level of 100, I should deduct 30 from the alkalinity test reading and then check for balance on their water wheel. I have followed those instructions for several years and have excellent looking water all the time. My marcite has looked great for 24 years until the last six months and it has developed some large areas that are starting to pit and stain. My question is, am I doing wrong by making the alkalinity adjustment and am I now beginning to see the error of my ways?

Thanks much for your opinions, Leon


me
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Postby me » Tue 12 Sep, 2006 19:06

Hi Leon,

Yes, as you know, in pool water alkalinity acts as a "buffer" to moderate pH swings. A "buffer" is defined as a weak acid and its salt. So you have carbonic acid and bicarbonates as components of alkalinity, but with higher levels of stabilizer you _also_ have cyanuric acid and its anion acting as a buffer. All these together show up as 'total alkalinity' when you do the titration.

You need to consider only the bicarbonate portion of total alkalinity for pool water balance and that's why Taylor suggests, for CYA levels greater than 100, substracting (CYA Level * 0.33) from the measured alkalinity reading to get the bicarbonate portion (which is what really counts).

So you're doing fine by applying the correction factor that's for sure. The pitting and staining may be caused by other factors, calcium hardness for example. Staining may be caused by metals.

Do you know what the calcium is at? And what about the stains, what color? If you could post pictures somewhere that would be great. Also, did you change _anything_ in the water, added salt, copper, acid (lots of it) a change of sanitizer maybe?

Keep me posted, thanks.
Guest

Postby Guest » Thu 14 Sep, 2006 10:26

Thank you for your reply. I strive to maintain CH at 300 but it can fluctuate between 275 and 325 and still work OK in the water balance wheel.

I do not put copper in the water because of the staining potential. I can't think on any metals that mighth be in the water and don't know how to test for any. The stains are dark yellow-green, like algae, but won't brush out. The pool does get alot of droppings from an Oak tree but the tannic acid stains usually come out pretty easily when I shock with liquid chlorine.

I am planning to try something rather novel. If I take a length of 2" PVC that is long enough to reach the bottom stains and pour 10% liquid chlorine into it, the chlorine should sink since the specific gravity of chlorine is heavier than water. I know it wouldn't last long but at least for a few minutes it should be pretty concentrated. What do you think?

Thanks again for your help. It is so helpful to have someone to discuss situations with. Leon
Guest

Postby Guest » Sun 17 Sep, 2006 08:46

Are you able to test for iron. Yellowish stains could be an iron problem
Guest

Cyanuric acid & stains

Postby Guest » Sun 17 Sep, 2006 19:12

I don't know how to test for iron but will see what I can find out tomorrow. Thanks for the tip, I'll let you know what I finds out. Thanks again, Leon
me
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Re: Cyanuric acid & stains

Postby me » Mon 18 Sep, 2006 19:49

Anonymous wrote:I don't know how to test for iron but will see what I can find out tomorrow. Thanks for the tip, I'll let you know what I finds out. Thanks again, Leon

Rub ascorbic acid on it (vitamin C), it goes away then its iron.
me
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Re: Cyanuric acid & stains

Postby me » Mon 18 Sep, 2006 19:52

me wrote:
Anonymous wrote:I don't know how to test for iron but will see what I can find out tomorrow. Thanks for the tip, I'll let you know what I finds out. Thanks again, Leon

Rub ascorbic acid on it (vitamin C), it goes away then its iron.


Oh, and I wanted to ask, any water heater, heatpump, SWG in the plumbing anywhere?
Leon
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Joined: Tue 14 Mar, 2006 13:38

Postby Leon » Wed 20 Sep, 2006 08:33

No, there is nothing in the plumbing other than a DE filter and 3" chlorine tablet feeder. I will find some acsorbic acid today and try it. Thanks very much. Leon

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