Where did the CYA come from?

[tim_pool_newbie]

When my new pool was first opened this summer, and before I knew anything about this forum or the BBB method, I was using dichlor granules and trichlor pucks. So obviously by the time I bought my TF100 test kit and measured my CYA level, it was no surprise to find it at 50. But now I'm using the BBB method and have introduced no CYA (that I know of) into my water and yet the CYA level is increasing slightly. A few weeks ago CYA rose to 60 (I realize with the inaccuracy of the test - and my interpretation of it!! - an error margin of +/- 10 isn't inconceivable, so I didn't think too much of the increase to 60). But yesterday I measured again and now my CYA has risen to 70.

I realize none of these numbers are catastrophic, and it just means I need to increase my bleach a bit. But I'm still curious as to where the extra CYA could be coming from.

The only other things I've been putting into the pool are:

Algaecide - 1/2 qt every other week (only because startup company gave me the stuff and instructed me to, so I'm using it up)
Les-iron - Only used this for the first few weeks and haven't added any since about 3-4 weeks ago.
PoolPerfect - Just started using this 2 weeks ago to help breakdown the excess tanning oils, etc.

Would any of these cause the CYA increase?

Any other explanations?

Thanks,
Tim

 

[257WbyMag]

CYA would only come from stabilized chlorine sources or from manually adding additional CYA.

 

[Melt In The Sun]

Tim, the accuracy of the test is +/- 10 under completely consistent circumstances (ie the same light, etc.). On different days, with different lighting, the results can vary even more than that. How long did you run on di/trichlor only? If you have a pretty good idea of how much you used per week or so, you can backtrack and get a pretty good estimate of how much you added. 50 sounds a bit on the low side, but that's just a guess.

 

[svenpup]

Have you seen the Snickers advert on TV where they wonder where the hunger goes, and it turns out that all the hunger goes to this one poor guy in germany?

There have been several reports recently of people adding CYA and it never registers on their test. Maybe all the missing CYA is going to your pool?!

 

[duraleigh]

Hey, Tim,

I would drain a little of the pool and refill....keep your CYA around 50.

Secondly, a true proponent of BBB wouldn't add things to the pool without having a specific need. All the things you are putting in your pool confuses the simplicity with which you should be managing.

Proper chlorination eliminates any need for algaecide and "Poolperfect".

Treat for iron if you have it but why treat it if you don't know?

I apologize for gettin' on your case just a little but I want you to keep that money in your pocket so you'll have more for adult beverages!! :lol: :lol:

 

[anonapersona]

It may be that the pucks that you were using had not had time to show up on tests yet. Although we say around here that it takes a week for it to show on tests, we read pretty often that it can take longer. How long has it been that the last puck was added? Based on how long it took for my CYA to show up using pucks, I am not too surprised at a 3 week time lag.

Also, are you careful to shake the mix for the directed time period? Could be user error on the tests, as you said.

About those other things, is there some sort of warranty that you need to keep in effect by adding these things? You may want to examine the paperwork. If you don't have to, you ought to consider just hanging onto most of those things.

A dose of algaecide is a nice thing to have when you are about to leave town, the pool is perfect but you are not so sure about the help who is supposed to add chemicals for you. I do wonder if the algaecide could have CYA in it, I have no idea.

Pool Perfect is enzymes, apparently to reduce scum from heavy suntan lotions. If you are not having lots of suntan goo in the pool, save that for the big pool parties when that may actually be needed.

Iron, well maybe the pool installer knows something that you don't about the local water supply. Ask the water company for the details so you know for sure.

 

[tim_pool_newbie]

Thanks for the feedback everyone.

I used dichlor and trichlor pucks for about 4 weeks before converting to the BBB method. I estimate I used about 20 3" pucks over that time (4 per week plus probably another 4 or so during a few heavy bather loads - maybe more). And I estimate about 12 scoops of dichlor during that same time (4 scoops/week - about 1 cup scoops). I'm not sure I know how to calculate the CYA added based on this info though.

The last of all of that was added around June 25th, when I converted to the BBB method. So it's been 5 weeks since the last CYA would have been introduced. Therefore I'm assuming it should all be showing up on tests by now, and so perhaps the disparity in my results is simply user error during the testing process. I follow the mixing instructions to the letter of the law, but it's difficult to really know when you're not seeing that black dot anymore!!

We've had a lot of rain here recently, and so I've actually found myself emptying a bit of the water due to that. I would have thought if anything, my CYA level would drop due to that dilution/emptying. Hmmm

As for the other things I'm adding (and no need to apologize Duraleigh - I'm still learning so appreciate the guidance), I've been adding the algaecide per the startup company's instructions and because I have the stuff here. But I do like your idea of just hanging onto the algaecide for when I go away on biz. As for the PoolPerfect, I just started using it and for the exact reason that anonapersona mentioned - to eliminate all the suntan lotion for very heavy bather load. Although the instructions say to add it weekly, I think I'm going to cut back on that and simply add some when I see the need for it.

 

[anonapersona]

OK, lets go look at the Pool Calculator. At the bottom, Effects of Adding Chemicals.

Need to assume a weight for the tabs, I'll guess 7 oz but they may be different, you should weigh one on a kitchen scale if the box doesn't say. 20 x 7 = 140 oz trichlor = 26 ppm CYA. 12 scoops at 8 oz (ignoring the difference between weight and volume here) = 96 oz dichlor = 16 ppm CYA.

Total 42. Not reasonable that you see the CYA of 50 - 60 - 70. I must have something wrong in the assumptions. Or there is something inthe algaecide which does not seem reasonable.

We need someone who can help here, I'm stumped.

 

[Bama Rambler]

If your testing is not suspect, then the CYA has to be coming from somewhere.
You dont have a tab feeder with some pucks left in it do you? Even if it's turned off.
Someone hasn't been sneaking out there and tossing a puck in when you're not looking are they?
I can't find any ingredients on the Pool Perfect and I don't know what Algaecide you're using but I don't think it's coming from there.

I'm leaning toward a testing issue. You might consider buying some CYA testing standard from TFTestKits and honing your testing skills with it.

 

[tim_pool_newbie]

Thanks everyone. I think I may have solved the puzzle. I'm leaning towards a combination of testing error and/or not knowing exactly how much dichlor/trichlor I really used.

First, I took out one of the 3" trichlor pucks and weighed it (I felt so "dirty" touching them instead of my bleach bottles!! LOL) - they're 7.4 oz - good estimate anonapersona!! But plugging in this new weight still didn't bring me up to where I'm seeing my CYA.

So then I decided to actually weigh the remaining buckets. Both the dichlor and trichlor buckets started with 25lbs each. Based on the remaining weights of each, I calculated that I must have used 170 oz trichlor and 169.6 oz dichlor. If you do the math you'll see that I was pretty close on my puck count, but apparently way off on my dichlor scoops. ... which is absolutely possible. During those weeks of using these products, with heavy bather loads, I found I was sometimes throwing in some additional scoops of dichlor to raise the FC level. I know, I know....what was I thinking?!!! I know better now!

So when I plug all that into PoolCalculator (thanks again anonapersona for pointing out I had that tool all along ), I get an estimated CYA level of 59. Therefore my 50-60 measurements are right on the money. My guess is that the recent 70 reading was a fluke testing anomoly.

But heck, about a week ago the pool store told me my CYA level was 30!!! Based on all these measurements I just went through, IMPOSSIBLE!!

Bama Rambler - no puck feeder and nobody else adding pucks. I doubt the algaecide has any CYA in it either. I'm chalking this one up to a slight testing variation on my last test.