Cya 100 + ?????

Maybe need help, not sure. New fiberglass pool installed in May 2012. CYA tested with K-2006 is at least 100 presently. FC is 4, CC is 0, PH is 7.4, TA is 90, CH is 170, CYA is 100. Have use stabilized TRI CHLOR tabs in auto feeder since pool was new in May due to installer reco. Have not added CH tabs since 7/13/12. FC and PH have always ran high till now. No, this is not a typo. Water has been stellar and still is clear and no odor.. Light load as grandkids mostly, a few adults occasionally. Should I be concerned? Please advise as I would rather correct CYA now if necessary. Thanks

There are many people here that regularly run their CYA at higher concentrations. You just need to adjust your FC ppm to match. See this chart to get an idea of where you would need to run yours.

I'm no expert. Just another newbie here, so am not trying to give advice. Just trying to point you in the right direction. One of the real experts should be along to get you on the right track.

You're going to want find out where your cya is really at. Since the test kit only goes to 100ppm, you can test above that by diluting your pool water sample 1-1 with distilled water. Run the test with the mixed sample and multiply your result by two. Do not use any more dichlor or trichlor tabs, that's where all the CYA is coming from. Plain unscented bleach (walmart usually has it for a good price), or liquid chlorine are what you need to be using at this point. With CH already at 170, I wouldn't use cal-hypo either.

Once you know your real cya level you can run your pool based on the high CYA as macox126 mentioned. Your other option is to do partial drains and refills until your pool water is diluted sufficiently to get you to a more manageable CYA level.

One thing to note, is that at CYA of 100 or more 4ppm fc is not effective at killing algae and you will get a green pool eventually. You need to keep the pool at at least 8ppm (somewhere between 8 and 15) and you'd have to take it up to 25ppm to "shock".

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Originally Posted by kelemvor

One thing to note, is that at CYA of 100 or more 4ppm fc is not effective at killing algae and you will get a green pool eventually. You need to keep the pool at at least 8ppm (somewhere between 8 and 15) and you'd have to take it up to 25ppm to "shock".

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The Best Guess chart page explains this.

Also, with a PF:7, your pool's FC (free chlorine) will be increased by 7 for each pound of chlorine gas equivalent added -- 1 gallon of 6% (chk %!) is about 0.5 lbs equiv, so will add about 3.5 ppm per gallon or 2.6 ppm per 96oz jug.

With a CYA of ~120, a dose of 3 gallons (4 96oz) would be a good start, possibly followed by 1 96oz jug per day, till you hit 20 ppm. Then, back off and hold in the 12 - 15 ppm range.

With CYA > 100 ppm, 20 ppm is NOT too high to swim. I've been running a large (>200,000 gallons) country club pool all summer at CYA in the 70 - 110 range (leaks a lot) and FC in the 8 - 20 ppm range . . . with NO complaints whatever.

Thanks for the lifetime subscription!

Thanks to all for the help.

Just adding my thanks as well. A lifetime subscription is a big help to the forum! Hope you enjoy being a member!