dilute water for pH test with FC 10+

[tedinelkgrove]

I thought I read somewhere about diluting water sample to get a more accurate pH reading when FC is 10+? Is this possible? Since my minum FC is always 10+, I am never really able to get an accurate pH reading. Should I let it drop below 10 once in a while?

I know I need to drain pool to lower CYA, which would also take care of this issue as well.

 

[Guest]

I thought I read somewhere about diluting water sample to get a more accurate pH reading when FC is 10+? Is this possible?

In a word, no.

I know I need to drain pool to lower CYA, which would also take care of this issue as well.

Bingo!

 

[tedinelkgrove]

are pH meters more reliable when FC is 10+?

 

[chem geek]

Assuming the meter is a good one and recently calibrated, then the answer is yes.

 

[duraleigh]

One of the things you will see quoted frequently on the forum is that pools with very high CYA can be dealt with but it is seldom worth the hassle. Yours is a good example.

Chem geek's response may lead you to some encouragement but let me damper that a little bit... Meters are not only expensive but their need for calibration is not a one time thing. Very, very few residential pool owners deal with them.

Eventually, a reduction in CYA will make your pool far more user-friendly in many, many respects.

 

[tedinelkgrove]

Agreed. It's time to bite the bullet, again, and drain some water.

 

[Guest]

Agreed. It's time to bite the bullet, again, and drain some water.

considering the cost of a GOOD pH meter (you are looking at a few hundered to say the least--remember I said a GOOD meter), the cost of standard solutions for calibrating the meter, the cost of replacement electrodes (they are delicate, need to be stored properly or they become useless, they break, and wear out), and the time involved to keep the meter calibrated you have made a wise decision.

 

[tedinelkgrove]

I am getting an early start tomorrow and heading out to rent the submersible pump. I am going to have the garden hose adding water as I pump out. I know the flow rate of the pump is greater than my hose, but I figure draining half the pool and adding fresh simultaneously will hopefully bring my CYA from 150 to 30-50ppm in one drain.

When I get the pool filled back up, what chemical levels do I want to address first, pH, FC/CC, CH, TA, etc?

Thanks.

 

[duraleigh]

what chemical levels do I want to address first, pH, FC/CC, CH, TA, etc?

Adjust your pH first. Then get your FC at the correct levels (or start the shock process) CH and TA can be considered fine tuning and your CYA should be very close to correct.

 

[tedinelkgrove]

Thanks for the replies. I am currently on second drain this weekend. The first brought CYA down to 70ppm. One more and my CYA nightmares are over. Hopefully I won't have to drain the pool again for years. Its not the work, its my wife about not being able to use the pool when it is 100+F today.

 

[tedinelkgrove]

After a long weekend draining and filling, the numbers are in:

CYA ~25ppm
TA ~110ppm
CH ~80ppm

pH 7.8
FC 4.5

For the CYA, i threw a trichlor puck in the pool. For CH I was going to Leslies to get some calcium increaser. Any other ideas?
I added HCl to bring pH down to 7.5.

 

[JasonLion]

Raise CYA just a little and CH quite a bit and you should be fine.