Adjusting pH and TA

[doglover78]

My levels:

SWG
FC 5.5
TA 70
pH 8.0
CH 240

Does it matter which I adjust first (pH or TA)? I hope not, as I've already added 1 cup of muriatic acid (31.45%).

It looks like you recommend a pH between 7.5-7.6. You seem to recommend a TA level of 60-80 but my Hayward SWG recommends 80-120 TA. Why the big difference?

FYI - I'm noticing scaling and some cloudy water when brushing.

I have a 15K gallon SWG pool.

 

[jblizzle]

I think we see this exact title twice a day recently.

Your TA is fine. Just lower the pH.

The higher TA will make the pH want to rise, the SWG also will make the pH rise. By keeping the TA lower, the pH should not rise as fast.

Scaling can start when you let the pH get too high (that is the biggest driver).

 

[chiefwej]

The key to preventing scaling is maintaining a CSI (calcium saturation index) at or very near zero. High levels of CH require lower TA and close monitoring of pH to keep CSI in line. If you plug all your numbers into the Pool Calculator it will give you the CSI.

I have extreme CH levels and need to maintain TA near 60 and keep a very close eye on pH to prevent scale.

 

[doglover78]

Okay. So Hayward's recommendation of 80-120 should be ignored? They're so much higher.

I just retested. My pH is 7.5 and my TA is now around 50-60...let's call it 55. Should I raise the TA up a bit to say 70-80?

 

[Richard320]

Okay. So Hayward's recommendation of 80-120 should be ignored? They're so much higher.

I just retested. My pH is 7.5 and my TA is now around 50-60...let's call it 55. Should I raise the TA up a bit to say 70-80?

I wouldn't bother. Sounds like you have hard water and it will go up again the next time you top off. You'll be playing see-saw if you obsess too much over this stuff.

 

[doglover78]

Oh okay. I'm using Taylor's K-2006 test kit. When I add the 5th drop of reactant the sample starts to turn from green to a light shade of pink/red but then swings back and holds steady at green. It's not until the 6th drop that it turns pink/red and remains that way. That's why I'm going with TA of 55...is this correct logic?

If I were to try to raise the TA using sodium bicarb I'd also raise the pH wouldn't I? Is that why you're telling me to leave it? TA of 50-55 is good enough?

I hear what you guys are saying on your recommendation of 60-80 but 50-55 is lower than your range, let alone WAY lower than what Hayward recommends. I'm just trying to understand as I'm just picking up this DIY pool chemist thing.

My levels are currently as follows:
FC 5.0
TA 50-55
pH 7.5

 

[Richard320]

Oh okay. I'm using Taylor's K-2006 test kit. When I add the 5th drop of reactant the sample starts to turn from green to a light shade of pink/red but then swings back and holds steady at green. It's not until the 6th drop that it turns pink/red and remains that way. That's why I'm going with TA of 55...is this correct logic?

If I were to try to raise the TA using sodium bicarb I'd also raise the pH wouldn't I? Is that why you're telling me to leave it? TA of 50-55 is good enough?

I hear what you guys are saying on your recommendation of 60-80 but 50-55 is lower than your range, let alone WAY lower than what Hayward recommends. I'm just trying to understand as I'm just picking up this DIY pool chemist thing.



My levels are currently as follows:
FC 5.0
TA 50-55
pH 7.5

Better go reread the instructions. Just because it turned pink, doesn't mean it won't get pinker. You keep adding until it stops changing, then discount that last drop that didn't make any difference. Most of the time I go from green to grey to pale pink to Barbie Pink. And then it stays there.

Incidentally, if you let the pool calculator calculate a baking soda dose, you can go plug it in down lower where it says Effects of Adding Chemicals and see how much - or in this case, how little - it affects pH.

 

[doglover78]

Ooooh. So, it's NOT when it FIRST changes color?! It's when it stops getting darker? And that applies for all of those color-changing tests? Dang.

My CH is 250, although that's when the sample FIRST turned blue. I guess I need to keep adding so it's probably a little bit higher, huh? I have a plaster pool if that helps.

So, TA may actually be 60 and CH may be 260 huh?

 

[Richard320]

Ooooh. So, it's NOT when it FIRST changes color?! It's when it stops getting darker? And that applies for all of those color-changing tests? ****.

My CH is 250, although that's when the sample FIRST turned blue. I guess I need to keep adding so it's probably a little bit higher, huh? I have a plaster pool if that helps.

So, TA may actually be 60 and CH may be 260 huh?

Could be. And the CH test will often keep changing with continued stirring and no additional reagent.

http://www.youtube.com/user/TF100TestKit

 

[doglover78]

FYI - I'm using the K-2006 test kit. Your link is in reference to the TF100. Does it make a difference? I still add until the color of the sample no longer gets darker?

 

[jblizzle]

The tests are identical between the 2 kits. Although you do not have the OTO test and you have the pH demand tests.

 

[doglover78]

So, do you all consider these low total alkalinity claims to be untrue? Should I ignore them?

http://www.poolwizard.net/problems/alkalinity.htm

The low end of the range I see elsewhere is 80. In your opinion, a TA of 60 in plaster will not cause problems.

I am seeing cloudy water when brushing and some stains on the bottom. I figured that was most likely do to the pH being at 8.0, though. Thoughts?

 

[Richard320]

Assuming your CYA is at the recommended 70, your Calcium Saturation Index is only slightly negative. If you have some scaling, that might actually dissolve it back into solution.

But the fact is, a cup of Muriatic Acid shouldn't have had that huge of an effect on your pH and TA.

If I was you, I'd worry more about testing technique and comparing the results with Effects of adding chemicals on http://www.poolcalculator.com/ than I would about some arbitrary target levels. Either you're testing wrong or your pool is nowhere near as big as you think it is. And until you get that sorted out, you'll be chasing numbers up and down endlessly.

 

[ping]

Oh okay. I'm using Taylor's K-2006 test kit. When I add the 5th drop of reactant the sample starts to turn from green to a light shade of pink/red but then swings back and holds steady at green. It's not until the 6th drop that it turns pink/red and remains that way. That's why I'm going with TA of 55...is this correct logic?

My guess is that if you add a 7th drop it will turn hot pink and the 8th drop will not do much. If this is the case, then the TA=70.