Alkalinity and pH issues

Jump to latest Follow Reply
J

joecooler

0
Jan 13, 2019
145
Longmont, CO
Back at the beginning of November 2019 I filled my spa and tested the TA at 40 so I didn't mess w/it. I brought the hardness up to 175 and I have an SWG for chlorine generation so I didn't do anything for FC. I have had ongoing issues w/high pH - started at 8 and has been creeping up to where it's now 8.2. I have tried adding some pH decreaser (spa store stuff, not MA), and it temporarily lowers the pH but it only lasts a day or two, and I was worried about dropping the TA lower than 40. I finally gave up and figured 8-8.2 is just where my tub is at. The water feels fine.
I'm planning on dumping the water in at the end of April so I thought I'd experiment w/trying to get the pH down. First thing I did was check the TA ... and it's 100! What the heck? How did it get so high? I haven't see anything about TA creeping up over time. I ran the test multiple times to be sure. I had also tested multiple times back in November and consistently got 40 back then.
Now I have something to work w/to lower my pH but I'd really like to know what happened w/my TA - is it possible for it to raise like that w/nothing added to the tub? FYI I have the TF-100 test kit so all my numbers are from that.
Any explanation of what happened here would be greatly appreciated!
 
I do add water, about once a month ... the tub seems to loose about an inch a month. I hadn't thought of that but that would change the chemistry over time wouldn't it? I have tried adding a little bit of pH down but not much ... it didn't seem to have a lasting effect, and since I thought the TA was at 40 I was worried about reducing it further.
 
Depends how the water is leaving the tub. If mostly via evaporation, then adding water will increase the TA as TA is not removed when water evaporates.
 
wireform said:
Check how to test your TA. You need to wipe the tip between drops and keep the bottle completely vertical every time AND do not force the drop.
Click to expand...

That is covered in the Notes in Total Alkalinity - Trouble Free Pool

Notes
  • Sometimes a static electric charge can build up on the R-0009 dropper bottle tip, causing the drops to be smaller than usual and making the test read higher than actual. You can prevent this by wiping the tip of the dropper bottle with a damp cloth or tissue before you start and after each drop.
  • Hold the dropper bottles vertically and squeeze gently, so that drops come out slowly and seem to hang on the tip of the dropper bottle for a moment before falling.
 
  • Like
Reactions: QuiltinMom and wireform
Did you add any stabilizer/CYA to your spa water to buffer the chlorine?
 
Drop size matters. Go slowly and let the drop fully form in the tip and fall off. Don’t squeeze the bottle and pop the drops off.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Just tried again but didn't realize about the not squeezing .... did wipe the tip each time and the drops looked bigger than before. Got a reading of a solid 90. I feel like my numbers are pretty good now - added 2 tbsp of pH decreaser yesterday (1 at a time, giving it multiple hours to circulate between additions) and my pH is down to 7.6 now and actually held overnight. I think I'll wait a few days to test again. Bottom line, that I didn't previously realize, is that I think I should be checking TA and pH more often as I add water to the tub .... as the TA rises over time I'll eventually need to add some pH decreaser to lower it and the pH, but that should give me a more stable and lower pH. Does that sound about right?
 
  • Like
Reactions: jseyfert3
I suggest you just manage your pH and don't focus do much on your TA.

FC and pH makes a difference in the 'health" of your water. TA does not.
 
My tap water has a TA of 30-40. It would make sense to me that as the H2O evaporate is would leave the solids behind and then as I add more tap water the TA would rise. Yes or no?

Re just managing pH, I've struggled w/this as it has been stubbornly high (8 and higher) and I didn't want to add too much pH down and wind up w/a really low TA. But now it seems like my TA was moving higher so I could have been lowering the pH w/out worry. Are you sure TA doesn't matter at all? Everything I have read (including here) suggests a TA of 40-50, or higher. The smarterspa people tell you to have a TA of 100.
 
joecooler said:
My tap water has a TA of 30-40. It would make sense to me that as the H2O evaporate is would leave the solids behind and then as I add more tap water the TA would rise. Yes or no?
Click to expand...

That is not the way the TA that we care about and affects pH works. TA and pH if left alone will reach an equilibrium.

What is the pH of your tap water?

Is your tap water coming from a municipal water system? Municipal water systems may artificially raise water pH to prevent pipe corrosion. So your water pH and TA is not in equilibrium.

joecooler said:
Re just managing pH, I've struggled w/this as it has been stubbornly high (8 and higher) and I didn't want to add too much pH down and wind up w/a really low TA. But now it seems like my TA was moving higher so I could have been lowering the pH w/out worry. Are you sure TA doesn't matter at all? Everything I have read (including here) suggests a TA of 40-50, or higher. The smarterspa people tell you to have a TA of 100.
Click to expand...

Normally, we recommend TA at 70 ppm for SWCG pools, but that may not be low enough for some pools.

We know that for spas using the Dichlor-then-bleach method, that 50 ppm TA works much better due to the heavy aeration from spa jets and the higher water temps.

As long as your pH is stable then TA doesn’t matter. It is unusual to find low TA and high pH in nature.

For a more techical explanation of TA read...

TA--What is it really?

xxxxxxxxxxxxxxxxxxxxxxxxxxxx
www.troublefreepool.com www.troublefreepool.com

and refer to this chart to understand the equilibrium pH and TA seeks...

 
Last edited:
You have to decide whose methods you want to follow and see what works best for you. Trying to mix recommendatiosn from different sources will just lead to confusion. TFP recommendations are backed up by science. Ask others what is the basis for their recommendations.
 
@joecooler I agree with @ajw22. Focus on pH. Don't focus on TA.

Let me explain why. My TA from the tap is ~400. This is so high if my pH is 7 and I run all my jets and air it will be 8+ within about 15-20 minutes. I perform the acid/aeration process, checking TA along the way, until I get to about a TA of 70. At this point pH rise is much reduced, and I only rarely test TA, just to give PoolMath an accurate number for calculating my acid additions. I am not testing TA to actively try and adjust the TA. I test pH regularly, as in multiple times a week when the spa is in active use.

Since your tap water has a low TA, you shouldn't be trying to actively adjust TA at all. It will naturally adjust as you actively test and adjust the pH. Measure your pH regularly (I recommend each time you check FC when the spa is in use, and once a week if the spa has not been used). If the pH is above 7.7-7.8, add some acid to target a pH of 7.4 using PoolMath. Test TA one a week, or once every two weeks, but don't try to adjust the TA. The TA will almost certainly end up between 50-70 if you target and maintain reasonable pH levels.

Does this make sense?
 
There is also a correlation between high PH and FC . High PH will render chlorine a lot less effective basically and cause FC levels to drop very fast. Whenever my hot tub FC starts to "loose" its effectiveness and drop to zero very fast right after adding sodium hyperchlorite, aka Bleach , (barring any problems with my liquid Stenner dosing system , which rarely happens) its almost always a high PH issue .
Usually this happens about once every month or two with my hot tub . The PH will slowly start to rise to crazy levels, then the FC seems to go lower and lower levels without any changes to sodium hyperchlorite dosages or strengths . I can go from adding my normal 2-3 oz of bleach per day to double that within a Month or two , and its still wont hold FC . Usually have to add add an ounce or two of muriatic acid to get the PH back in check , then the FC "usage" goes back to normal for a while . Until the PH starts to creep up again .

Just noticed mine this week . PH was up to about 8.2 (or higher), and TA was up to around 170ish . Added 2 ounces of Muriatic, and it brought the PH back down to 7.3/7.4 , and TA is back down closer to 100 . Now the FC is working great and holding again . (my hot tub CYA is about 30) .

I never realized that high PH , can really mess with FC levels . It will really make you crazy trying to figure out where your FC is going , even though you keep adding more and more chlorine when all your levels are perfect except high PH .
 
Last edited:
jseyfert3 said:
@joecooler I agree with @ajw22. Focus on pH. Don't focus on TA.

Let me explain why. My TA from the tap is ~400. This is so high if my pH is 7 and I run all my jets and air it will be 8+ within about 15-20 minutes. I perform the acid/aeration process, checking TA along the way, until I get to about a TA of 70. At this point pH rise is much reduced, and I only rarely test TA, just to give PoolMath an accurate number for calculating my acid additions. I am not testing TA to actively try and adjust the TA. I test pH regularly, as in multiple times a week when the spa is in active use.

Since your tap water has a low TA, you shouldn't be trying to actively adjust TA at all. It will naturally adjust as you actively test and adjust the pH. Measure your pH regularly (I recommend each time you check FC when the spa is in use, and once a week if the spa has not been used). If the pH is above 7.7-7.8, add some acid to target a pH of 7.4 using PoolMath. Test TA one a week, or once every two weeks, but don't try to adjust the TA. The TA will almost certainly end up between 50-70 if you target and maintain reasonable pH levels.

Does this make sense?
Click to expand...

For some reason I stopped getting notifications of replies so I missed this. Yes, this makes total sense. Thanks for the explanation!

I have been frustrated trying to lower my pH because it has been so stubbornly high. Do I just need to keep banging away at it - will it eventually come down and stay down? Or will it always drift up and need attention?
 

Enjoying this content?

Support TFP with a donation.

Give Support
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply