Very high CYA levels, HELP!

[Mindiv]

I'm completely new to pool ownership but I'm having to learn quickly. Here is my problem. We opened the pool for the first time (closed by previous owners) and are now having issues. The pH was really low at 6.2, clearly no chlorine and they had been using copper for algae and left us a bottle and told us to dump it in on opening so we did. Now I have shocked, and been raising the pH but now my CYA levels are suddenly sky high at 150. Turned off the chlorinator and raised the chlorine level with bleach (it was only 2).

So here is where I am.

35,000 gallon, in ground vinyl pool with no main drain (thanks previous owners) just skimmers.

Free chlorine is 5.0
Combined chlorine is 0.4
pH up to 7.6
TA 180
CYA 150

Water is crystal clear.

Chlorinator off, using bleach (much to the pool companies disagreeing) to keep chlorine around 5.

Back flushing and wasting with vacuuming but I can only empty to bottom of skimmers and more importantly I can only fill off my well...VERY slowly.

So here is my question. I know I have to replace water. The pool companies insist simply converting to liquid chlorine of some sort and doing the usual backflushing but with vacuuming to waste that I can slowly lower the CYA and that will be enough over the summer so as not to stress my well. But both of these companies also insisted that high levels of CYA wouldn't effect my needed shock levels and that "4 bottles of liquid shock" would be enough (mind you they didn't even ask what my current chlorine levels is).

Is this true or do I need to find a way to empty more with a submersible pump and some how get a pool water company into my backyard? Can I just keep going and shock as needed for blooms or is this going to be a never ending project?

I'm petrified every time I go outside that my pool will be green and I'm a full two weeks into pool ownership with my first major crisis.

THANK YOU!!!!
Mindi

[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 (http://richardfalk.home.comcast.net/~richardfalk/pool/OBrien.htm)

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-water-chemistry-t628.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 (http://www.sciencedirect.com/science/article/pii/0160412080900355) and this paper (http://www.nrcresearchpress.com/doi/pdf/10.1139/v90-043)). 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.

[Mindiv]

Ben and Chem Geek you both rock!! Actually makes complete sense but that would be because I was a marine bio major with serious chem background and now I'm a physician assistant and live in the scientific world. That is exactly what I thought and explained to my pool guy. He didn't understand prior to our conversation that the tests measured bound and unbound (I made a darned good guess, but based on the reality of binding to stabilize I figured that had to be the case). He had always just done the usual "Chlorine lock" crap. Referenced this forum so maybe I have created another convert or maybe he was just thinking I'm a lunatic! ;-)

Either way...pleasantly happy with my first swim in a FC of 9 and found it much more comfortable than lower levels at other pools. THANK YOU POOLFORUM!!!!!!!! Now off to read all the referenced materials. I would like to speak with authority when people question my way of dealing with my pool this season until my CYA levels are lower and frankly from here on out.

[chem geek]

In my post above, I added a couple of links to papers talking about how the bound chlorine is measured in FC tests and the reaction rates for release of chlorine from bound CYA.

I also want to note that there are two effects from the higher FC at higher CYA even when keeping the FC/CYA ratio constant. The first is that the chlorine bound to CYA is not completely "inactive" as I had indicated. As noted in the following paper:

Effects of isocyanuric acid on the monochlorodimedone chlorinating rates with free chlorine and ammonia chloramine in water (http://www.sciencedirect.com/science/article/pii/S0043135401004821)

The reaction rate of chlorine bound to CYA could be as much as 1/150th that of hypochlorous acid. So an FC of 9 ppm with 150 ppm CYA would have 0.024 ppm hypochlorous acid (in ppm Cl2 units) at pH 7.5 and 77ºF temperature, but could have up to 9*(1/150) = 0.06 ppm additional equivalent oxidizing power from the chlorine bound to CYA. Since we normally aren't dealing with such high FC and CYA levels, we normally ignore this effect though it may at least partly explain Ben's experience with seeing more effects from such high levels.

The other effect is due to the higher FC being a higher capacity or reserve that will continue to oxidize when one gets out of the pool and the water starts to evaporate. This is tricky to figure out because while there is more capacity to keep on reacting for longer, it's unclear what the increase in concentration from water evaporation will do. All the chemical components increase in concentration equally and ultimately one would end up with precipitate of CYA and possibly Trichlor, but as the active chlorine level goes up it will react as well as outgas so maybe that occurs fast enough to result in only CYA precipitate and no Trichlor. So maybe there is more risk towards oxidizing skin and swimsuits after getting out of the water with high FC, but it's not at all clear if this effect is large enough to be noticeable (i.e. I'm just speculating here). A decent experiment for this would be to notice any difference in chloramine smell on your skin in the high FC and CYA vs. lower FC and CYA (but both with the same FC/CYA ratio), but of course you'd have to have the same sweat conditions for a decent comparison.

Compare this with what is typically the case in many indoor commercial/public pools that use no CYA. Even with 1-2 ppm FC, they have at least 10-20 times the active chlorine level of the outdoor residential pools following Ben's chart. That's a HUGE difference in oxidation rates of swimsuits, skin and hair as well as in the rate of creation of disinfection by-products including smelly and irritating nitrogen trichloride. My wife experienced this difference every year when she swam for 5 months over the winter in an indoor community center pool. She had to buy new swimsuits every season as their elasticity would get shot and her skin would be flaky and hair frizzy. In our own pool used 7 months over the summer season, her swimsuits would last for 7 years and the effects on her skin and hair were noticeably better.