CYA Confusion

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M

MHumphrey

0
Sep 11, 2014
24
Winter Springs, FL
When I do the CYA test that is included in the TF-1000 kit, it fluctuates between 60 and 80. Over the course of the last 6 weeks, it has gone from 60, up to 70, then 80, then back to 70 and today it was 80 again. Is this because I'm not doing the test correctly (or judging the results correctly)? Or can CYA really go up like that? I chlorinate using 10% liquid chlorine and I have not used tabs or anything else with conditioner (I've only ever put liquid chlorine, Muriatic Acid and baking soda). In those 6 weeks, the pool level has gone up about 4 inches, then down about 2 inches due to rain/evaporation.

What else can affect CYA?

Thanks
-Matt
 
I'm thinking some of this fluctuation could be some testing error from reading the results differently. Are the lighting conditions the same every time you took the test ? That can affect your results some. Are you doing the test more than once with the same sample? You can do the test with the same sample a couple of times by pouring back and forth to verify your results.
You can have lower CYA levels from splash out and topping off.
I did read a post on another thread about the CYA getting more concentrated with evaporation and read a higher level when tested on the lower water level. Don't quote me on this until somebody verifies this. It was the first time I've heard of it. ?
 
For the most part, the lighting is the same. I don't do the tests at exactly the same time, so I suppose that could play a part but I wouldn't think much.

I think the problem I am having is just me and judging the results. Basically, I'm looking down into the tube with one eye, and squirting the stuff in. What I notice is that as soon as I stop squirting the bottle, the black dot becomes visible again very quickly. So as i'm filling the tube, I have to stop because i can't squeeze the bottle anymore. When i do that, the fluid settles, and I see the sticker. I don't know. I guess probably the truth is my CYA level hasn't really changed that much, if at all. Just not sure what the "real" answer is.

If there are any tips or tricks to make sure you are getting an accurate CYA reading, i'd love to hear it.

Thanks
-Matt
 
I'd like to start off by thanking you for joining us at TFP! We hope we can help answer any questions you may have. :wave:

One positive is that there is some "wiggle room" for this test. One main reason you would want an exact CYA level would be to determine your FC level. Let's take a quick look at the ranges for these results.....

60ppm CYA5-9ppm FC
70ppm CYA5-10ppm FC
80ppm CYA6-11ppm FC

As you can see, there's really not much difference between your FC "goals" as long as you're not SLAMMING the pool. Keep your FC levels above 6 at all times and you've got yourself covered while you train your eyes in reading the CYA test. It takes some practice at first, however in short time you'll find yourself getting consistent results the majority of the time.
 
MHumphrey said:
When I do the CYA test that is included in the TF-1000 kit, it fluctuates between 60 and 80. Over the course of the last 6 weeks, it has gone from 60, up to 70, then 80, then back to 70 and today it was 80 again. Is this because I'm not doing the test correctly (or judging the results correctly)? Or can CYA really go up like that? I chlorinate using 10% liquid chlorine and I have not used tabs or anything else with conditioner (I've only ever put liquid chlorine, Muriatic Acid and baking soda). In those 6 weeks, the pool level has gone up about 4 inches, then down about 2 inches due to rain/evaporation.

What else can affect CYA?

Thanks
-Matt
Click to expand...
Since your signature indicates that the pool was resurfaced this year (therefore, recently filled with new water), and since you say you don't add anything containing CYA during routine maintenance, I'm assuming that the CYA in the water is there because you intentionally added it to the new water. If you know how much conditioner you added when the pool was refilled, that should give you an idea of what level should be in the water -- maybe a good cross check on the level you are reading using the CYA test?

Of course, if someone else added the initial chemicals after the resurfacing job, this information may not be available to you.
 
As pwrstrk said, a 50PPM CYA comparison solution is the best option. The fluctuations sound to me like test /read error. ...and go ahead and order now the large (8oz) CYA test solution. I'm guessing this is going to drive you crazy :)
 
The CYA test has an accuracy of plus or minus 10 - 15 ppm. Generally, the more experience you get with the test you can get it to repeat quite a bit better than that. Newbies to the test report those fluctuations but they seem to taper off with practice.
 
Thanks to everyone for their replies. I figured that it was just my eyes, and needing to practice, as it pretty much says as much in the instructions. But just trying to get a handle on how the chemicals behave. Another one is the Calcium Hardness. This one seems much less subjective as it's pretty clear when it changes from red to blue. But i get results between 400 and 475. What influences the CH Levels?

We purchased this house a few months after the pool was resurfaced. I know the previous owner had a pool guy who was using the chlorine tabs, which I think had the conditioner in it. I have not used the tabs, and as I said, have only used liquid chlorine since i took over.

Thanks
-Matt
 

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The largest contributor for an increase in CH for a lot of pool owners is the fill water they have. Calcium does not evaporate and when you need to add water to the pool the CH will increase with how much calcium is in the fill water. Another source of calcium is from Cal-Hypo if that is used to chlorinate the pool.
 
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