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
Pool Care Proficient
Pool Care Proficient
Posts: 31
Joined: Mon 08 Oct, 2007 11:03

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.


chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

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
Pool Care Proficient
Pool Care Proficient
Posts: 31
Joined: Mon 08 Oct, 2007 11:03

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
Swimming Pool Wizard
Swimming Pool Wizard
Posts: 75
Joined: Thu 06 Jul, 2006 20:43

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.
Pool repair guy
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

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).
Jeffm
Pool Care Proficient
Pool Care Proficient
Posts: 31
Joined: Mon 08 Oct, 2007 11:03

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?
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

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
Jeffm
Pool Care Proficient
Pool Care Proficient
Posts: 31
Joined: Mon 08 Oct, 2007 11:03

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.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

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
Jeffm
Pool Care Proficient
Pool Care Proficient
Posts: 31
Joined: Mon 08 Oct, 2007 11:03

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"
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Is CYA of 70 ppm too high?

Postby chem geek » Wed 29 Apr, 2009 11:53

Well I can tell you that he's wrong. The ongoing use (addition and consumption) of bleach or chlorinating liquid or any other hypochlorite source of chlorine will not raise the Total Alkalinity (TA). It will raise the salt level as will all sources of chlorine though the hypochorite sources increase it more. I will say that with an Endless pool in operation there is a lot of aeration so that will tend to make the pH rise quickly if the TA is higher so the way to mitigate this is with a much lower TA and, if needed, the use of 50 ppm Borates.

Take a look at Cyanuric Acid and compare it to Dichlor and Trichlor. Do you notice any similarities? Essentially, Dichlor has two of the three hydrogen attached to nitrogen replaced with chlorine while trichlor has all three hydrogens replaced with chlorine. When in water, the Dichlor and Trichlor release some of the chlorine into the water forming hypochlorous acid. The core CYA ring doesn't go anywhere so the CYA level absolutely rises. To say that stabilized chlorine does not increase CYA is completely wrong and to say that it won't affect the effectiveness of chlorine is also wrong.

To be continued in next post since there is a limit of 5 URLs per post (ARGHHH!!!!).
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Is CYA of 70 ppm too high?

Postby chem geek » Wed 29 Apr, 2009 11:54

(continued from previous post)

The relationship between chlorine and CYA has been known definitively since at least 1974 as described in the scientific paper in this link (you can read the intro section in the paper since it is somewhat non-technical). As for CYA's effect on chlorine effectiveness, there are many papers on this from the 70's and 80's as shown here, here, here, here and

(to be continued on the next post because of the 5 URL limit!!!)
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Is CYA of 70 ppm too high?

Postby chem geek » Wed 29 Apr, 2009 11:55

(continued from previous post)

here.

I suggest you read the Pool School to learn the truth about what really happens in pools. The pool and spa industry has not been well-trained and even the official courses (NSPF CPO and APSP TECH) still withhold certain basic facts or disclose misleading information such as chlorine vs. pH charts that simply do not apply when CYA is present. So don't blame your pool stores -- they are just getting incomplete or incorrect information from the manufacturer sales reps and from an industry that doesn't seem to care very much about integrity. I'm trying to change this, but am amazed at the amount of resistance to even disclose basic chemical facts such as how much the CYA rises from stabilized chlorine or CH rises from Cal-Hypo, let alone the chlorine/CYA relationship.

Richard
Jeffm
Pool Care Proficient
Pool Care Proficient
Posts: 31
Joined: Mon 08 Oct, 2007 11:03

Is CYA of 70 ppm too high?

Postby Jeffm » Wed 29 Apr, 2009 15:38

Sodium Hypochlorite = Liquid Chlorine, right?
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Is CYA of 70 ppm too high?

Postby chem geek » Wed 29 Apr, 2009 20:03

Yes. Sodium hypochlorite is in both bleach and chlorinating liquid aka liquid chlorine (though technically it's not really liquid chlorine since chlorine at room temperature is a gas, but people call it that anyway).

Return to “Chlorine”

Who is online at the Pool Help Forum

Users browsing this forum: No registered users and 11 guests