still cannot get a bead on my pH

[CombatYoga]

I posted a few days ago about not being able to get a reading on my pH.
I had let my waterfall run for a very long time and thought that the pH had gotten high (it typically tracks upward anyway).

I discovered that my SWG was running for too long and had driven my FC up to 16.
When FC is that high, you can't get an accurate pH reading.

I have waited for my FC to drift down (turned off the SWG) - it is now 4.5.

I still cannot get a reading on pH - it is a very deep orange color that doesn't match anything on the color block.

When I put only 1 drop of pH reagent in, it looks like it measures 7.2 (very light orange-ish color), but by the third drop it turns into this very deep orange-reddish color
that doesn't match anything. I honestly have no idea if my pH is really high, or really low.
I have put quite a bit of muriatic acid in the pool over the last couple of days, guessing that my pH is high, but it does not seem to be changing the color when I test.

Perhaps it is extremely low?

This is really getting frustrating - I can't seem to recover the pH into a range that I can read.

Full test results:
FC 4.5
CC 0
TC 4.5
ph ???
TA 40
CYA 65

Any ideas?

SF

 

[anonapersona]

I note that your TA is at 40. This makes the pH quite unstable. I suggest that you raise that TA to about 70 and then see where pH is. Probably baking soda is best, as that raises TA and does not affect pH so much, since I don't really know what your pH is now.

Wiser minds may have better advice, but locating some baking soda in the 6 lb bags at Walmart now will probably be a good thing to do. They are cheap but harder to locate late in the swim season. Also try Sams Club.

 

[Richard320]

Very low pH would be my guess, based on the low TA and your admission that you were blindly adding acid. If you have a K-2006 test kit, you can use the base demand reagent to confirm the pH is below the test range. Otherwise, look for borax in the grocery store, or head to the pool store or a big-box hardware store and look for soda ash aka pH up.

Remember pH is a logarithmic scale; so you won't see an even progression where each cup of powder equals a certain pH rise.

 

[duraleigh]

Your pH is low I am virtually certain. TA up to 70 first is a good idea. 20 mule team borax is what you need to raise pH.

 

[CombatYoga]

Looks like overshot trying to bring TA up - I used baking soda and obviously put in too much:

FC 6
CC 0
TC 6
TA 90
CYA 65
pH ??? <--- still indicating an intense red color

I am aerating now to bring pH up; once I can determine pH, I'll add acid lower pH and TA, and then aerate again to raise pH.

Anyone see issues with that plan or have an alternative suggestion?

Many thanks for the help!

SF

 

[duraleigh]

it is a very deep orange color

pH ??? <--- still indicating an intense red color

?????? Those are not the same. orange-ish red or purplish red?

 

[dmanb2b]

Can you post a pic of the test block...might help us decipher. If your TA is now 90+ and still no PH reading, I'd almost bet your PH is high.

 

[CombatYoga]

Here is a progression of pictures taken after each drop is added to the test block:

1 drop (looks like somewhere between 6.8 and 7.0)

2 drops (looks like a good match to 7.5)

3 drops (has already turned a color of red that doesn't match anything on the test block)

4 drops (just gets a more intense shade of red)

5 drops (more of the same)

 

[jblizzle]

I never see that dark red ... mine looks like your 2-drop picture.

Any chance you are using the wrong reagent? There is a different test with a larger tube and wondering if the reagent would be meant for it (and thus not give the dark colors)?

You should be using R-0014 (any chance you are using R-0004 ... which is for the larger test cylinder?)

 

[CombatYoga]

YOU ARE THE MAN!!!! I'm staring at the reagent right now - it says R-0004.

I recently replaced my reagent, and clearly I bought the wrong one. I saw a red cap and "pH INDICATOR" on the side and didn't think twice.

If you are ever in Austin, I owe you a beer!

Thanks Jason,

SF

 

[jblizzle]

Glad we got that figured out

What I am not sure of is whether just using 1 or 2 drops in the smaller vial would give accurate results or not. The ingredient is the same but the concentration is different. I suppose if you tested with 5 drops of the R-0014 and compared with 2 drops of the R-0004 you could find out if it was usable.

Maybe Dave will stop by again with insight.

 

[jblizzle]

difference-taylor-ph-r-0004-r-0014-t19175.html
ph-phenol-red-taylor-reagents-r-004-and-r-0014-t37257.html

Looks like 2 drops should work.

 

[ping]

The good news is that it looks like the pH is about 7.5, no harm done.