CYA Problem!!

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bmann71

bmann71

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LifeTime Supporter
Aug 3, 2007
55
Washington, Indiana
I last posted a question in 07 and now have another one. I've been having some water balancing issues that I'm starting to get corrected except this one. I searched the forum for this problem before posting but didn't see anything like this.
I have a 20,000 gal Fiberglass pool. I'm using liquid chlorine as my only sanitizer. I placed 6lb of Stabilizer in my skimmer, checked over a week later and...I still show zero CYA. I'm using the Taylor K-2006 test kit and purchased the Stabilizer from Intheswim.com. It's 99% pure.

I have a brother who has become somewhat of a "poolman" and he too is stumped.

As much as I hated to I placed another 6lbs in the skimmer on Tuesday (6/26), checked it on Wednesday (I know it takes time to register but just wanted to see) and it was somewhat cloudy. I could see the dot with the tube completely filled. I then checked it last night again and guess what...it was completely clear! :rant:

It can only be 2 things right? Bad Stabilizer or bad reagent. I bought new reagent a year or so ago but didn't think it would go bad.

I'm still going to check in another week to see what the reading is but wanted to post to see if there could be something/anything that could be somehow destroying my CYA. I read that over the winter it's been known to be eaten by bacteria but not this...

my current readings as of last night were
FC .5
PH 7.2
Alk 170
CH 290
water temp 84°

I added a half gallon of 12.5% chlorine. I plan on doing an OCLT tonight since I'm now not able to hold any chlorine (even over night).

thanks for any and all help.
 
I added a half gallon of 12.5% chlorine. I plan on doing an OCLT tonight since I'm now not able to hold any chlorine (even over night).
Click to expand...

If you can't hold any FC even over night, something is definitely eating your chlorine. I suggest that you do not add any more CYA yet.

Maybe bacteria or ammonia. Either way, the cure is to shock the pool per directions in Pool School.

What & when was the last readable CYA test you had?
 
Thanks for the quick reply.
My last readable CYA was last fall. I'm not at my house so I don't have my numbers handy but I believe it was around 60. This spring it was zero. My Taylor test kit stops at 30 and two nights ago like I mentioned it was "cloudy" all the way filled but i could still see the dot.
 
bmann71 said:
Thanks for the quick reply.
My last readable CYA was last fall. I'm not at my house so I don't have my numbers handy but I believe it was around 60. This spring it was zero. My Taylor test kit stops at 30 and two nights ago like I mentioned it was "cloudy" all the way filled but i could still see the dot.
Click to expand...
You're welcome.

Well, CYA going from 60 to zero and not holding FC sounds like it converted to ammonia.

As I mentioned, shocking is the cure. If you want to, you can test for ammonia. Pet shops/wallyworld sell an inexpensive (<$20) ammonia test kit or some pet stores will do an ammonia test free.
 
I guess it varies greatly but is there a time frame I can expect to perform the OCLT before it starts to hold if ammonia is the problem? Will that affect my shock amount? Pool Calc shows I'm at 10. Do I buffer to 13-15 to be sure?

One other question. I assume it's not wise to swim till I do this test correct? Haven't called home today but it's probably safe to say my kids are swimming. It's only 105 here in Indiana so that's where I'd be if I was 10! :-D

Thanks again!
 
OK. I just completed a week long shock process to my pool. I kept my ppm above 13 for the duration (I had little to no CYA) When I started the process I was losing 7-9 ppm per hour. I just passed an OCLT last night. I used a total of 42 gallon of 12.5% liquid chlorine (our local Rural King had a special on it, 4 gallons for 8.99 so I stocked up!).

I've read you need 3 things to happen before you are done.
1. Crystal clear water ?
2. 1ppm loss or less over night ?
3. .5 CC or less X

I passed the first 2 items but I'm still registering 1.0 of CC. I've been averaging 1.0 to 1.5 for the duration of my shocking.

Like I mentioned I've been shocking for a full 7 straight days. I have a solar cover that helped in this process so I was able to maintain shock even during our recent heat wave (been above 100 just about everyday I've been shocking).

Do I continue till I no longer register CC or can I lower my chlorine (it's at 15.5 right now) and actually use the pool? I of course don't want to waste the last 7 days if doing that could cause me problems but the kids have been remarkably cooperative during this time so I'd like to let them swim sometime this summer. :)

thanks for the help.
 

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It sounds to me like you got some bad stabilizer. There's been some reports about that and subsequent CC readings from using it, possibly because it contained non-CYA compounds that chlorine reacts with and registers as CC. If it's something like urea, then you really need sunlight exposure breaking down the chlorine during the day to help get rid of that since the breakdown of chlorine produces hydroxyl radicals that are very powerful oxidizers.

If there is truly no CYA in the water at all, then in an average depth pool and at pH 7.5 you'd lose half the FC in about an hour in direct noontime sun. I suspect you've got at least some CYA in the water otherwise you'd see a more rapid FC drop during the day. Does the pool smell bad at all or is it just a chlorine bleach-like smell?
 
Chemgeek, thanks for responding.

The pool doesn't smell bad from what we can tell. Wouldn't the solar cover prevent the loss of FC during the day at a rapid pase. I've been averaging .25 to .35ppm loss during the day with it covered. I haven't been home this weekend so I was just able to take it off around 4 p.m. (est) today to see if that helps.

I just did a CYA test and it was clear all the way to the top on Taylor K-2006 test vile.

Will the suggestion made by imwarren for the sun to help eliminate CC not work?
 
Yes, an opaque cover will prevent the chlorine from degrading from sunlight. If you uncover the pool and the CYA were zero, then you could lose half the FC every hour around noontime. So if you do that, stick around and add more chlorine as needed. The good news is that as chlorine breaks down it produces very powerful oxidizers (hydroxyl radicals) that may clear up the CC and the UV in sunlight might help directly as well. You'll also need to find a reliable stabilizer even if you keep it somewhat low (20 or 30 ppm) because you keep it covered most of the time. In my pool, I have it at 40 ppm and use a mostly opaque safety cover. I used to use 30 ppm CYA but found that even having the pool open for about an hour every day and longer on weekends it was using a little more chlorine than I'd like. Now it tends to use somewhat less.
 
Well the Sun exposure worked to eliminate the CC. I have finally passed all three checks. Thanks for this website and I have already recommended it to 2 co-workers and 3 friend's this past week.

Below are before and after pics. It's somewhat hard to tell in the before pic but it's basically bath water. Couldn't see beyond a foot down. Now it's crystal clear. :party:
 

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