Having trouble interpreting pH results today

suziequsie2945 · Jul 1, 2014

I never had issues with figuring out our pH using the basic OTO test kit for pH and chlorine. Well, today, I am having a major issue determining what our pH is as I have never seen this color before. Yesterday, our pH was fine and is usually somewhere around 7.6 or so, but today, it is a more red color, and I can't tell if it is darker than 7.8, or lighter than 7.8 and somewhere in between 7.5 and 7.8. Anyone run into this before? Tried taking pics to show you guys but the pics do not come out good enough as to where you can tell the exact color.

What would a reddish color indicate? I'm assuming it goes from that brownish-pinkish tone at 7.5 to a more reddish color (between 7.5 and 7.8) and then to the purplish color at 7.8 and beyond, is that correct?

Richard320 · Jul 1, 2014

High FC can do weird things to the pH test. It reacts with the red stuff and makes it go purplish.

Dump it out and try it again.

suziequsie2945 · Jul 1, 2014

Richard320 said:
High FC can do weird things to the pH test. It reacts with the red stuff and makes it go purplish.

Dump it out and try it again.

Hi Richard,

Our FC is only at 4. I tested again three more times and same color, that reddish color. I am guessing it is closest to 7.8. Not sure.

At this point with a pH climbing up higher over time, and a TA of only 70, would it be ok to add some acid to bring down pH a bit with that low TA? Or should I leave pH be for now?

jblizzle · Jul 1, 2014

If the pH test looks red, then it most likely is too high and you need to add acid to lower it. You never mentioned a TA value.

suziequsie2945 · Jul 1, 2014

jblizzle said:
If the pH test looks red, then it most likely is too high and you need to add acid to lower it. You never mentioned a TA value.

TA of 70, which I mentioned above. How did it jump from yesterday to being okay to way too high today? I check it daily.

So, when you say too high, what number? I have no clue what number to use when calculating how much acid to put in. It is not as dark/purple as 8.2, but seems closer to 7.8, but not even in the "purple" shade family, so I have no clue what I am dealing with.

Also, my TA a bit on the low side. How much will the acid affect that?

jblizzle · Jul 1, 2014

OH, that TA is fine.

You are looking at the colors not me. Try one fewer drops or one extra drop and see if that helps you match colors.

suziequsie2945 · Jul 1, 2014

jblizzle said:
OH, that TA is fine.

You are looking at the colors not me. Try one fewer drops or one extra drop and see if that helps you match colors.

Thank you. That was helpful. For some reason, when I added four drops first, and then added a fifth drop a second or two later, it came out more purplish, closest to 7.8

Would you add acid with a pH of 7.8, and a TA of 70 at this point? If so, what would you want the pH to come down to? We're getting ready to swim now so I would probably add the acid later on or tomorrow.

jblizzle · Jul 1, 2014

As long as it is in the 7s you are fine.

Richard320 · Jul 1, 2014

suziequsie2945 said:
Thank you. That was helpful. For some reason, when I added four drops first, and then added a fifth drop a second or two later, it came out more purplish, closest to 7.8

Would you add acid with a pH of 7.8, and a TA of 70 at this point? If so, what would you want the pH to come down to? We're getting ready to swim now so I would probably add the acid later on or tomorrow.

Plug your numbers into poolmath and target 7.4 pH. Dribble the acid in front of the return and maybe make a couple passes in the area with the brush to get it to disperse, and go ahead and get in. You'll mix it faster than the pump alone will.