Ph Question

[firepilot]

Hi All,

Quick question about PH. I read that PH is not real accurate with FC above 10. My FC is coming down now as I am done shocking it. It is down to 11.5. My PH as I have been measuring is down to 7.2. What should I do at this point? Should I wait until FC gets down to 7 and test again for PH?

What is the soda ash I need to get to raise the PH?

Thanks

Phil

 

[duraleigh]

Should I wait until FC gets down to 7 and test again for PH?

Yes, but don't be surprised if it remains @ 7.2.

I strongly suggest the use of 20 Mule Team Borax (from the grocery store in the Laundry section) to raise pH.....not soda ash

 

[JamesW]

What are your TA (Total Alkalinity) and your CYA (Cyanuric acid) levels?

 

[firepilot]

Ok thanks. Off to find some mules

Phil

 

[firepilot]

So on the borax add the same amount in ox as it calls for the soda ash?

I found 4 lb boxes here at a local place for $3.79 each

Thanks

Phil

 

[firepilot]

Hi Again,

Ok got back from running around and redid all my tests. Here are the results. We have had some rain and wind and had a lot of stuff in the water when I got home.

Here are the results from just a min ago.

FC = 11.5
PH = between 7.2 and 7.5. The color was hard for me to call. My son thinks closer to 7.5.
TA = 110
CH = 190
CYA = 65

Not sure why the CH is so different form the other day. i don't think I measured it in about 3 days. I thought it was pretty constant.

I have in stock now Clorox, Muratic acid, and 20 mule Team.

Thanks

Phil

 

[JasonLion]

The quantity of borax to use to raise PH is roughly double the quantity of soda ash. You can use the Pool Calculator to get exact numbers for either one.

As long as your PH is at least 7.2, I suggest leaving it alone. With TA around 110, the PH will tend to drift up (perhaps quite slowly), and it should eventually get to where it needs to be. There is a possibility that PH will go below 7.2 as the FC level comes down. If that happens, raise the PH back up to 7.2 (or slightly higher).

 

[JamesW]

Most likely, the pH is going to be correct. I have found that having a significant amount of cyanuric acid in the water, relative to the FC, greatly slows down the interference from high chlorine levels.

It's important to mix the test sample and reagent, and match the color right away. Allowing the sample to sit can give the chlorine enough time to interfere with the test.

The TA of 110 also suggests that the pH is most likely correct.

Also, if the pH was at least 7.2 before you shocked, and you shocked with sodium hypochlorite, lithium hypochlorite or calcium hypochlorite, then the pH should not drop.

However, if you used trichlor or dichlor, then the pH could have dropped.