Sudden pH rise

[amjohn]

We had been using a solar cover to keep the water temp around 82 degrees, but fall finally arrived, and we had to give it up. pH had been a stubborn 7.2 - seemed like the solar cover was surpressing the pH. TA was 100.
Took solar cover off 2 days ago, started shocking due to a bottom dwelling algae/pollen problem- I was not keeping FC high enough- I may have been misreading the CYA tube.
Now, pH is 8, with TA only gone to 110.
Changes: No solar cover
Temp of pool dropped 10 degrees in two days
1.5 inches of rain
switched from cal-hypo 65 to bleach for chlorine
air temps dropped 20 degrees
Question 1: On reading the CYA tube- when is the dot "gone". I was adding the test water with CYA reagent to the tube until the dot was completely obscured- not even a hint of a shadow. That gave me a CYA reading of 45. Keeping my FC at 5 based on that reading allowed algae to happen twice- though both times there has been contamination added to the pool around the same time- a fact of life in the country.
If I read the tube at the point where the dot is mostly obscured, just a shadowy outline, I get a CYA of 60- a pretty big difference. Which one is right?
FC is currently at 13,
CC=0 (I hardly ever get a reading there, even when I cannot see the bottom of the pool),
CH=150,
TA=110
Water is somewhat cloudy with a yellowish-green tinge and the bottom has lots of pollen/algae (probably both, pollen is a fact of life here). However, about 1/3 less than the day we took the solar cover off and did a thorough vacuum and backwash
My shock level depends on my CYA level, which I was taking to be 45 and was using a shock target of 16
Question 2: Do I need to do anything about the pH yet? Is that large of a jump common with shocking? When I was using Cal-hypo 65% to shock (a week ago) and with the solar cover still on, I only saw the pH go to 7.5, but I was shocking to 16- same level as now.
Picture coming shortly.

 

[duraleigh]

Hey, Amjohn,

Lower your pH below 8 sooner rather than later. anywhere from 7.2 to 7.8 is acceptable but 8 is too high. Use muriatic to bring it down to maybe 7.4 to be ideal.

If I read the tube at the point where the dot is mostly obscured, just a shadowy outline, I get a CYA of 60- a pretty big difference. Which one is right?

Probably somewhere in the middle but favoring the 45. You should not be able to see the dot but it sounds like you are making sure it's obliterated. The test is never precise and I'd say you are around 50ppm which is just fine.

From your pics, it appears to me you have some mustard algae forming in your pool. That's not an analysis but a guess based on my experiences. I would suggest you do an ovenight FC loss test (post back if you don't know exactly how to do that) and my guess is you'll find youneed to shock the pool.

Once it's cleared I would also suggest you keep your FC a little higher than recommended (say maybe 20%) for your CYA level. I believe you will then have no further problems with water clarity.

 

[Butterfly]

Hi amjohn,

Question 1: On reading the CYA tube- when is the dot "gone".

You're not the only one who has had problems learning how to read the CYA test!

See if this visual helps (scroll to bottom pf page):

http://www.taylortechnologies.com/Chemi ... ntentID=44

 

[meatloaf]

Thank you for posting that link,
http://www.taylortechnologies.com/Chemi ... ntentID=44
I too have trouble reading the test. I thought my results were 80, only to have it professionally tested and got 108
Thanks again

 

[JasonLion]

have it professionally tested

There is no reason to believe that the "professional" is any better at doing the test than you are. And given that they got a reading of "108" there is strong reason not to believe their result. (It is impossible to have anything like that kind of precision when testing CYA.)

 

[meatloaf]

I thought that result was a little high myself. Even my test strips (which I know are not very accurate) show a result of about 70-80.

 

[duraleigh]

There is no reason to believe that the "professional" is any better at doing the test than you are.

I want to say how strongly I agree with Jason's statement.

Time after time on this forum, we find that the pool owner tests more accurately than the pool store. Sometimes because the owner is armed with a better kit but frequently because the owner cares more about his pool than the pool store.

 

[amjohn]

I have been shocking to FC=16 for the last two days. pH is 7.8 today. I will continue shocking, brushing, vacuuming, backwashing until things are as clear as they can get- however I always have some sediment in the bottom of the pool. We live in a rural area surrounded by hundreds of acres of pastures (literally) and this is peak ragweed season- you can see it blowing in the air. Every month is peak something season here.
The clear picture with sediment was taken before the solar cover went on- all values normal, no CC, no FC change at night, and as you can see, no cloudiness. Right now, I would believe I have some algae along with the pollen, but I had very little FC loss last night- about 1. The water is still not clear, and there is still a fair bit of sediment on the bottom.

 

[amjohn]

Also, thank you Butterfly for the post of the Taylor site on how to read the CYA test- it appears that I was getting a little overenthusiastic in trying to "drown" the dot. It does also appear that my pool needs a little more FC than "normal" because we do have so much contamination.

 

[Butterfly]

Thank you for posting that link.......I too have trouble reading the test.
Thanks again

You're welcome meatloaf! :lol:

Also, thank you Butterfly for the post of the Taylor site on how to read the CYA test- it appears that I was getting a little overenthusiastic in trying to "drown" the dot.

:lol: Too funny! and, you're welcome amjohn.

A couple years ago I had problems reading the CYA test. Sound familiar? Maybe I was trying to drown that dot, too! chem geek (Richard) gave me this link and it has been a great help not only to myself, but many others! Thanks Richard!

 

[amjohn]

Well, the pollen/mustard algae has been shocked away, water is sparkly clear. Turn out my CYA is 60 using the picture from Taylor technologies to match the test- that would explain a lot. FC is holding at 14 after a high of 16 two days ago- definitely very little loss there. Shocked for a week at 16-18.
pH and TA are coming down a little- my eyeball return may aerate more than I realized. I pointed it down as much as I could, we will see if that helps.
pH=7.5-7.8
TA=100
CYA=60
CH=150
Below are the after pictures: just a few minor deposits of something that is bright yellow. It looks granular, but poofs when I brush it. Pollen?