Is CYA of 70 ppm too high?

Chlorinating, maintaining the right chlorine levels,
chlorine problems. Dichlor, trichlor, cal hypo, bleach,
granules, chlorine pucks and chlorine sticks.
Jeffm
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Is CYA of 70 ppm too high?

Postby Jeffm » Sat 25 Apr, 2009 15:36

So, if you read my other posts, I've got an indoor pool (Endless Pool). Just checked my CYA and it's 70ppm.
Keep in mind there is alot of stainless steel in the pool. Is this too high?

I'm guessing it came from my granular cholrine, I sure didn't add it.


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Is CYA of 70 ppm too high?

Postby chem geek » Sat 25 Apr, 2009 21:01

It came from the Dichlor you used. See my post in the other thread where you bring this up. You only needed a very small amount of CYA in your indoor pool -- perhaps 20 ppm. So don't add any more stabilized chlorine (Trichlor or Dichlor).
Jeffm
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Is CYA of 70 ppm too high?

Postby Jeffm » Sun 26 Apr, 2009 11:02

Think I should replace half the water?

(apologies for the dual postings, thought this might help others)
Pooltech32
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Is CYA of 70 ppm too high?

Postby Pooltech32 » Sun 26 Apr, 2009 21:53

probably don't need too, just make sure you add fresh water often and backwash once per week, you could even top the pool up with water right before you vacuum the pool and vac to waste.
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Is CYA of 70 ppm too high?

Postby chem geek » Mon 27 Apr, 2009 02:09

Ditto. As I posted in the other thread, you'll either need to keep your FC higher or use an algaecide or phosphate remover to prevent algae growth. You can certainly manage a pool with higher CYA, but you can't do so at lower FC levels without additional algae inhibition (unless you are lucky and your pool is already bereft of algae nutrients such as phosphates and nitrates).
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Is CYA of 70 ppm too high?

Postby Jeffm » Tue 28 Apr, 2009 07:32

So, I've drained 1/2 to 2/3 and filled. I looks like my CYA is down to 35/40 now. New test kit coming and will take a sample into the local pool supply to confirm a few numbers.
I'm trying to lower my alkalinity now, since it's usually a bit high after filling with well water.

I'm using the acid and aeration method, and I'm noticing that the chlorine level seems to drop more rapidily than when I was using granual cholorine. Am I imagining things, is this normal, is there a non-stablized granual that might be better than bleach? I believe that bleach has an alkaline content and will slowly raise my alkanity over time...true/false?
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Is CYA of 70 ppm too high?

Postby chem geek » Tue 28 Apr, 2009 09:51

Once the chlorine is fully dissolved in the water, it is identical regardless of its source and will remain in the water the same. Aeration will tend to outgas some chlorine so maybe that is what you are seeing, though it shouldn't be much different than what happened if you've done this before. It's possible that the strength of the chlorine you are using isn't as expected -- if you test the FC level before and after adding it (about a half hour after adding it if you have your pumps on and have decent circulation) then that can tell you if your chlorine is as strong as you think.

If you use 6% Clorox Regular unscented bleach, it has the least amount of "excess lye" with a pH of 11.4 (off-brand Ultra bleaches usually have a pH of 12.5 or higher). While the pH goes up when you add any hypochlorite source of chlorine (including Cal-Hypo), the pH will drop back down as the chlorine gets used/consumed because that is an acidic process (a technical explanation of this is here . Long-term, it's pH neutral. If you find that the pH in your pool is rising over time, it's most likely due to outgassing of carbon dioxide since pools are intentionally over-carbonated. Lowering the TA helps to reduce this effect as does use of a pool cover.

Richard
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Is CYA of 70 ppm too high?

Postby Jeffm » Tue 28 Apr, 2009 11:42

I am using Cholorox 6%.

I do understand the pH give and take quite well. Again, that's not my concern, it's the gradual alkanity rise that takes places. If I'm not mistaken, the liquid bleach has a high alkalinity content to it, which will raise my pool's alkalinity over time.

Does anyone sell a granular cholorine that doesn't contain stabilizer? (i.e. won't raise my CYA level).
I guess I'm not fond of using lquid bleach for some reason.
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Is CYA of 70 ppm too high?

Postby chem geek » Wed 29 Apr, 2009 00:56

No unstabilized source of chlorine raises alkalinity. Total Alkalinity is raised by baking soda (Alkalinity Up -- sodium bicarbonate) and also by washing soda (pH Up -- sodium carbonate). It also rises some from Cyanuric Acid (CYA) including that from stabilized chlorine. It also rises from adding water high in TA.

However, evaporation of water and subsequent refill with fill water will add whatever is in the fill water into the pool. So if the fill water is well water high in TA as you say (and probably also CH), then those levels would increase if there were evaporation and refill.

Since you said your pool was indoors, I would assume that evaporation isn't as high or that you use a pool cover so the above should not be an issue. Are you sure that what you heard wasn't that hypochlorite sources of chlorine (bleach, chlorinating liquid, Cal-Hypo, lithium hpochlorite) are alkaline (that means they are high in pH, but as noted earlier, chlorine usage is acidic).

Richard
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Is CYA of 70 ppm too high?

Postby Jeffm » Wed 29 Apr, 2009 08:41

Y'know, my well water CH varies.
The first time I filled the pool (June of 07) my CH was 400/420.

I filled it this Feb/March and my CH was 165. I'm attributing the low CH to the frozen tundra of Wisconsin. During the winter there would be no rainwater seeping through the limestone into the reservoir. But who knows. Now, I just drained 1/2 and filled, we'll see where it's at.

I may have misunderstood, but I'm pretty sure he said bleach would raise TA. I've got two different pool supply stores, and this forum, and quite honestly 3 different opinions. Just had one guy tell me that stabilized chlorine will not raise CYA, and that high CYA will not effect the level of chlorine needed. Yet...on the test strip package I purchased it says "high CYA can decrease the effectiveness of Chlorine"

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