Very high CYA levels, HELP!

[PoolDoc]

You can run your pool successfully with either bleach (or 'liquid chlorine') OR calcium hypochlorite, without draining, and without getting algae.

BUT . . . . to do so you have to move firmly to the BBB method and completely turn your back on pool store chemistry.

To start, read the 'Best Guess Chlorine' page, till you understand it, or at least till you can do what it says. And, order a K2006 test kit, because you cannot maintain the chlorine levels you need, without it. There are links to both the Best Guess page, and to Amazon K2006 ordering, in my signature.

Meanwhile, use bleach or liquid chlorine. To use cal hypo, you'll have to get a calcium hardness test result from the K2006, and tell us what sort of filter you have.

[Mindiv]

OMG, THANK YOU!! After reading I'm a believer and completely understand. BBB here I come!

Ok, so I do have the K-2006 and my filter is a sand filter. Not sure of the size but big, up to my waist and the pool company that was out to look at our heater thats not working said the filter was oversized for the pool.

Bumping my chlorine up to 8+ per the Best Guess Chart using the Pool calculator. The CYA was greater than 100 on the black dot test and on my strips that had 100, 150 and 300 it was squarely on 150. The pH, FC and CC were off the K-2006. I just did the hardness and its 210. We have really hard water here and the hose comes off before the treatment system to save the system a bit. We do as I mentioned have a heater but we are vinyl.

I might actually sleep tonight and not dream of green pools. THANK YOU AGAIN BEN!!!! I'm practically in tears I'm so happy. You made my day, week, month and probably summer. Any additional ideas will make my year. This is now my go to forum and time to start reading the archives.....

[BigDave]

Test strips for CYA are nearly useless. You can test for high CYA levels with your K-2006 by diluting the sample with tap water. Mix equal parts pool water and tap water then test the mix for CYA and multiple the result by 2.

[Mindiv]

Thank you Big Dave! Repeated with the K-2006 and got 140-150 (70-75 diluted) for CYA.

[Mindiv]

Trying to explain to an old friend why high FC levels with high CYA isn't as irritating as the same FC level with lower CYA. Just trying to convince them that my pool is indeed safe! It is amazing to me how many people don't know that high CYA levels require higher FC levels.... Any references? I tried a search with no luck.

[PoolDoc]

It is amazing to me how many people don't know that high CYA levels require higher FC levels.... Any references? I tried a search with no luck.

Not that amazing to us.

I published the first material to that effect, based on my experiences and John Wojotowicz's articles in the JSPSI. Richard "ChemGeek" dug into the chemistry of it, and provided the rigorous analytical foundation for understanding the issue, based on his analysis and the O'brien article (on which Wojotowicz had depended).

About a decade after I first published the first version of the "Best Guess" chart, 10,000's of users here and at TFP have established repeated field validation of that analysis.

But, even now, only my sites (PoolForum and PoolSolutions) and TFP consistently acknowledge these facts. To my knowledge no one 'officially' in the pool industry has done so.

The same is true of the 'step-by-step' approach to alkalinity control that I originated -- even though that approach is well-established in both the potable and waste water treatment industries (though I only discovered that after the fact), only PF/PS and TFP teach this approach.

Truth, when it steps on established practices and profits, is never popular. This is just as true among evangelicals as it is among atheists; among Democrats as it is among Republicans; among industrialists as it is among environmentalists. A friend of mine once observed that trying to serve the truth is like trying to wield a sword equally sharp at the handle, as the end: no one is safe around it.

[chem geek]

If you need technical references, there is the original O'Brien paper from 1974:

Equilibria in Aqueous Solutions of Chlorinated Isocyanurate

and there is my analysis of the equilibrium constants from that paper to derive why the FC/CYA ratio is a decent proportional proxy for the active chlorine (hypochlorous acid) level:

http://www.troublefreepool.com/pool-...28.html#p50548

The bottom line is basic equilibrium chemistry where the primary chemical components at typical pool pH are the following (the ppm assume the following is the only reaction, but there are actually others that are less dominant):

HClCY- + H2O <<<---> H2CY- + HOCl
"Chlorine Bound to CYA (Inactive)" + Water <<<---> CYA + "Unbound Chlorine (Active)"
........ abt. 9 ppm Cl2 .................................... 150 ppm CYA .... abt. 0.024 ppm Cl2

Most of the chlorine is bound to CYA and the total CYA level is typically much higher than that so if the CYA level rises then you need to proportionately raise the Free Chlorine (FC) level to maintain the same amount of active chlorine. The FC measured in tests measures both the unbound and bound chlorine since the reaction above moves to the right quickly as active chlorine gets used up in the test (technically, half gets released every 0.25 seconds -- see tihs paper and this paper). Equilibrium chemistry says that the following is a constant (at a given temperature):

[CYA]*[Unbound Chlorine (Active)]/[Chlorine Bound to CYA (Inactive)]

So as CYA rises, you need to increase "Chlorine Bound to CYA (Inactive)" by the same proportionate amount to keep the active chlorine level the same. Since most of the chlorine is bound to CYA and is measured as FC, it's easiest to just say to raise the FC proportionately when the CYA rises -- which is the same thing as saying to keep the FC/CYA ratio constant.

I know, I know, TMI.