CYA 100

[Gregd]

Hello everyone. First post here. Great and very helpful site. I have spend a few hours reading the recent posts this past week trying to get on track with everything. This will be my 10th season with the in ground pool I have. Everything has been going well with it over the years. But I have noticed that the last few years it's taking longer and longer to get the water crystal clear when opening. This year it took 2 weeks and I used much more clorine that I have in years past. 25 gallons of 12.5 percent liquid and around 25 pounds of 3" tablets. Plus 60 pounds of baking soda this year so far. Been open 4 weeks. Right now the water is looks great. I wanted to add I haven't changed the sand in the filter yet after 10 years.
I picked up a TF-100 test kit this past week. Results below.
CL 5+
PH 7.2
FC 9.0
CC 0
TA 110
CH 20
CYA 100
What do you think ? Thanks for any input. I tend to overload the pool with clorine and let it go down low and repeat.
Thanks for any and all input. Greg
I edited the results to correct the TA reading

 

[duraleigh]

What do you think ? Thanks for any input. I tend to overload the pool with clorine and let it go down low and repeat.

Welcome to the forum. :lol: .

1. Your TA looks like a typo??

2. A more even application of chlorine is a much better way to sanitize your pool. Have you seen the FC/CYA chart in Pool School? Those target and min ranges would probably serve you much better.

3. Importantly, your CYA is too high....that may be the reason it is getting harder and harder to clear your pool. I would suggest you do a partial drain/refill to get CYA down to 50 ppm.

4. While it never required to change the sand, it is a very good idea to open the filter every couple of years and inspect the bed.

 

[JasonLion]

One of several problems with CYA at 100 is that the common CYA test will report any level over 100 as if it was 100. That means your CYA level could be far higher than 100.

Higher CYA levels required higher FC levels to be effective. Chances are that you haven't gotten anywhere near shock level because your CYA is so high.

I recommend replacing water until your CYA level is at least below 100, and preferably down around 50.

 

[woodyp]

That much baking soda should have raised your TA to 170ish. You might want to run that test again. Also, perform the CYA test using half of the sample bottle with tap water and multiply your results by two. I'm guessing your CYA is far in excess of 100. See the criteria in pool school for shocking your pool. If it passes all three criteria, then there is no need to shock. Also see the chlorine/cya chart there for what range your FC should be in per your cya level. No need to change your filter sand. Welcome to the forum!

 

[Gregd]

Yes a typo on TA, 11 drops = 110. Thanks for the reply. Greg

 

[Gregd]

Ok thanks everyone for the replys. I went back and tested TA and it was the same. We have had alot of rain sence opening the pool so that may have lowered it some.
I went back and tested the CYA again using 50 percent tap water (city water) in my water sample to simulate a 50 percent water change. I got a reading of 60. So I suspect the actual CYA reading is 120. Does anyone think it's a big mistake to delay the water change until next spring when opening the pool ?
I will follow up after checking the criteria for shocking pool.
Thanks Greg

 

[duraleigh]

Does anyone think it's a big mistake to delay the water change until next spring when opening the pool

Maybe, maybe not. If you manage your pool VERY carefully and keep your FC where it belongs, you will use some extra chlorine over the summer but not excessively.

If you let your water go South (algae), you will regret having left the CYA in there at it's current level.....you will consume a LOT of chlorine getting your water back to clear.

 

[lee872]

With CYA that high, you'll need to keep you FC high all summer, and when you need to shock you'll need many more gallons of liquid chlorine. Have you looked at the Chlorine/CYA chart in pool school? It will give you a good idea of what you'll be using for chlorine this summer under both options. It will be a lot more trouble to maintain with the high CYA --- cost comparison of refill and chlorine price will help you decide if all the trouble is worth it.

 

[JasonLion]

Unless there is a water shortage in your area, or you have to get water trucked in, I would lower CYA right away. The extra effort now will be well worth it.