Old hot tub guy looking to learn new tricks...

CuckooChris

Well-known member
Sep 14, 2016
59
Coplay, PA
So how do I keep the PH from spiking, I don't like adding an oz of dry acid every day..

I have somewhat similar water, very low CH from the tap. I don't really worry about keeping the TA at a certain level and only focus on PH. My TA is usually 30-40 and my PH hovers around 7.6-7.8. When it gets up to about 8, I put in a Tbsp on muriatic acid and that lowers it a few notches. I've found keeping it simple works best for me, just liquid chlorine and muriatic acid (and testing 2x a day). I have used MPS but that always made my PH drop like a rock and then I'd have to add baking soda to raise it again, so I stopped using it. I've only had the tub about eight months or so, so I'm still learning. But after 3 purges with Ahhsome now, it's really easy as long as you have the time to test.
 
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CuckooChris

Well-known member
Sep 14, 2016
59
Coplay, PA
You guys really push that Ahhhsome stuff here.. get a kickback or something?

Most regulars may remember that I was a skeptic at first. I thought it was just pulling junk out of the water like a protein skimmer in a salt water aquarium does. Well, after the last purge, I really started noticing a difference in my chlorine usage, I'm only putting in an oz or two a day compared to four or so. So, yeah, I'm a believer now. No kickbacks:)
 

A.O.

Well-known member
Apr 12, 2016
234
Kershaw, South Carolina
So testing today
FC-0
TA-50
PH 8+
So I added my 1.7 oz of chlorine
Added .9 of dry acid
And I threw in a capful of Dichlor.. Maybe if I raise my CYA a bit my PH wont spike as bad... we'll see.
Tried to log it into my phone but it wont let me, I guess one log in is all that's allowed.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,408
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Tried to log it into my phone but it wont let me, I guess one log in is all that's allowed.
You must upgrade to the Premium subscription to store test data. CYA does not buffer pH. Dichlor is acidic so your pH was dropped and TA may have dropped.
 

A.O.

Well-known member
Apr 12, 2016
234
Kershaw, South Carolina
I'll just store data in my head then, it has worked well for years that way, I dont need another un-necessary expense
And I need to do something to keep my PH from spiking so bad, never had this problem before, and you said earlier that the CYA pushes the PH down, now you are saying it doesn’t?
 
Last edited:

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,408
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
you said earlier that the CYA pushes the PH down, now you are saying it doesn’t?
Did not say that. CYA is acidic. It will lower pH. It will not buffer it, or keep it from changing so rapidly.
 

A.O.

Well-known member
Apr 12, 2016
234
Kershaw, South Carolina
So this isn't working with the TA so low (50) so I'm bumping it back up to a normal level in that 80-100 range and see how the PH does. With the TA so low there just isn't anything there to buffer the PH... We Shall See!
 

santacruzpool

Gold Supporter
Feb 24, 2015
771
Santa Cruz, CA
Not to pile on, but you are getting lots of expert help that has been used on more than 1000's of functioning TFP spas.

Let me tell you about what I do with help from this site.

I have high TA fill water and no matter what I do until I get the TA to 50, or more often 40 in my Hot Tub, I don't get the PH to stabilize. So my advice is to focus on doing what you can to keep the PH from rising - once it settles down and stops rising daily, or even hourly, I suspect the TA will be at 50, or a bit under, which is perfectly fine. Anything else and you are just chasing your tail.

I look at the PH/TA numbers as a separate number from my FC. I use CYA at the very beginning on its own - instead of dichlor - during a new water fill I try to hit my 30-40 CYA target and then I just focus on the FC numbers - keeping FC in the 3-4 range.

I am now using a SWCG drop in generator and I dial that in over time and adjust it based on hot tub use and temps - I don't even think about PH/TA when I adjust the free chlorine number - I think of them as separate battles. They are interrelated but once the PH/TA is stable I can just focus on the FC amounts and happily use my tub.
 
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A.O.

Well-known member
Apr 12, 2016
234
Kershaw, South Carolina
Not to pile on, but you are getting lots of expert help that has been used on more than 1000's of functioning TFP spas.

Let me tell you about what I do with help from this site.

I have high TA fill water and no matter what I do until I get the TA to 50, or more often 40 in my Hot Tub, I don't get the PH to stabilize. So my advice is to focus on doing what you can to keep the PH from rising - once it settles down and stops rising daily, or even hourly, I suspect the TA will be at 50, or a bit under, which is perfectly fine. Anything else and you are just chasing your tail.

I look at the PH/TA numbers as a separate number from my FC. I use CYA at the very beginning on its own - instead of dichlor - during a new water fill I try to hit my 30-40 CYA target and then I just focus on the FC numbers - keeping FC in the 3-4 range.

I am now using a SWCG drop in generator and I dial that in over time and adjust it based on hot tub use and temps - I don't even think about PH/TA when I adjust the free chlorine number - I think of them as separate battles. They are interrelated but once the PH/TA is stable I can just focus on the FC amounts and happily use my tub.
And just what can I do to keep the PH from rising? I have it at the 7.6 ish number in the afternoon and in the morning after 1 or 2 uses its well over 8.
 

santacruzpool

Gold Supporter
Feb 24, 2015
771
Santa Cruz, CA
MA=Muriatic Acid - I wait for the PH to stop rising - preferrably looking for it settling in the 7.5 - 7.8 range and once it stays there for a long period of time I am good. I sometimes hit it one time extra with MA and it will stick at 7.2 for a couple of weeks - I am OK with that but aim for it to be higher. Anything in the 7's and stable is what you are aiming for. PH of 9 is way way to high
 

A.O.

Well-known member
Apr 12, 2016
234
Kershaw, South Carolina
So after raising my TA yesterday, my PH did not spike so wildly. It did raise to about the 7.8 level but not way up in that 9 range like every other day this week. So I'm thinking I'm heading in the right direction!! I'll watch it over the next few days and see how it does. YAY
 

A.O.

Well-known member
Apr 12, 2016
234
Kershaw, South Carolina
MA=Muriatic Acid - I wait for the PH to stop rising - preferrably looking for it settling in the 7.5 - 7.8 range and once it stays there for a long period of time I am good. I sometimes hit it one time extra with MA and it will stick at 7.2 for a couple of weeks - I am OK with that but aim for it to be higher. Anything in the 7's and stable is what you are aiming for. PH of 9 is way way to high
Thanks for the help, just trying to understand all this. Picked up a gallon of 31% MA this morning. And you say to keep adding the MA till the PH stops rising , so does the MA build up in the water to do this? So add MA what is called for every day till the PH stops rising, yes?
 

santacruzpool

Gold Supporter
Feb 24, 2015
771
Santa Cruz, CA
With 31% MA you will need around a teaspoon at a time to adjust your levels. Be careful to not add to much - luckily MA does not build up. The only issue is using too much.

I use 14% stuff and even dilute it to use in the hot tub and have a bottle sitting near my tub for adjustments.

Using Pool Math add the right amount of MA each time your PH goes above 8 - targeting the new amount of 7.2 - you will repeat this for a bit of time until the pH stabilizes and sits in the 7's. You will also need to adjust it periodically based on it moving. Mine still creeps up with use, the SWCG and especially when I add water to top it up - that really changes things.

When I get the PH stable it can stay that way for a week or two many times.
 

A.O.

Well-known member
Apr 12, 2016
234
Kershaw, South Carolina
With 31% MA you will need around a teaspoon at a time to adjust your levels. Be careful to not add to much - luckily MA does not build up. The only issue is using too much.

I use 14% stuff and even dilute it to use in the hot tub and have a bottle sitting near my tub for adjustments.

Using Pool Math add the right amount of MA each time your PH goes above 8 - targeting the new amount of 7.2 - you will repeat this for a bit of time until the pH stabilizes and sits in the 7's. You will also need to adjust it periodically based on it moving. Mine still creeps up with use, the SWCG and especially when I add water to top it up - that really changes things.

When I get the PH stable it can stay that way for a week or two many times.
Whoa... According to the pool math app it said I needed 1.2 oz , which I did which brought me to the 7.4 range.
So if the MA does not build up what is it that makes the PH stabilize in that 7's range?
 

jseyfert3

Silver Supporter
Bronze Supporter
TFP Guide
Oct 20, 2017
1,480
Southern WI
Pool Size
15000
Surface
Vinyl
Chlorine
Liquid Chlorine
You guys really push that Ahhhsome stuff here.. get a kickback or something?
Not at all. TFP is a non-profit, and all of us here are volunteers, we don't get paid. I've never met or talked to anyone from this site except through the site itself. Because of the recommendations here, I used Ahh-Some when we bought a house with a hot tub and I saw the results with my own eyes, which I documented here with pictures for others to see. I'm assuming this is why it's "pushed" here so much. It works, and so we recommend it.

Whoa... According to the pool math app it said I needed 1.2 oz , which I did which brought me to the 7.4 range.
So if the MA does not build up what is it that makes the PH stabilize in that 7's range?
No. MA does not make the pH stabilize. What makes the pH stabilize is a TA that is low enough that offgassing does not raise the pH very fast. While I haven't read this entire thread, I skimmed the last few messages. You're correct that TA is a pH buffer, but raising it won't slow pH rise. I can try to find the post with the exact chemistry, but in short water with a high TA will have a pH rise caused by aeration. And aeration is something spas have loads of. So while the TA buffers pH changes, it also causes pH rise when there is aeration. This pH rise slows as the TA is lowered, eventually usually stabilizing out at a TA of 40-50.

For spas where dichlor is often used, a higher TA can be of use, as dichlor is acidic and so counters some of the pH rise. This may be why the "industry standard" for TA is often quoted at 100 or so for spas. But too much CYA causes issues with chlorine keeping the water clean, which is why when following the TFP advise of ~30 ppm CYA and then using liquid chlorine to avoid CYA buildup a lower TA of 40-50 is needed since an acidic source of chlorine is not added on a regular basis.

Does this make sense?
 

A.O.

Well-known member
Apr 12, 2016
234
Kershaw, South Carolina
Not at all. TFP is a non-profit, and all of us here are volunteers, we don't get paid. I've never met or talked to anyone from this site except through the site itself. Because of the recommendations here, I used Ahh-Some when we bought a house with a hot tub and I saw the results with my own eyes, which I documented here with pictures for others to see. I'm assuming this is why it's "pushed" here so much. It works, and so we recommend it.


No. MA does not make the pH stabilize. What makes the pH stabilize is a TA that is low enough that offgassing does not raise the pH very fast. While I haven't read this entire thread, I skimmed the last few messages. You're correct that TA is a pH buffer, but raising it won't slow pH rise. I can try to find the post with the exact chemistry, but in short water with a high TA will have a pH rise caused by aeration. And aeration is something spas have loads of. So while the TA buffers pH changes, it also causes pH rise when there is aeration. This pH rise slows as the TA is lowered, eventually usually stabilizing out at a TA of 40-50.

For spas where dichlor is often used, a higher TA can be of use, as dichlor is acidic and so counters some of the pH rise. This may be why the "industry standard" for TA is often quoted at 100 or so for spas. But too much CYA causes issues with chlorine keeping the water clean, which is why when following the TFP advise of ~30 ppm CYA and then using liquid chlorine to avoid CYA buildup a lower TA of 40-50 is needed since an acidic source of chlorine is not added on a regular basis.

Does this make sense?
Yes it does, thank you very much! Finally a response of not only what to do but the part I needed... why to do it.

I did switch to liquid chlorine because I'm well aware of the amount of CYA normal spa chlorinators add to the water, but since doing so I've had high spikes of PH every day and am working on controlling that. And I just picked up a bottle of the MA which I have used in the past so I'm pretty familiar with it, just don't want to have to add an oz a day to knock my PH down!! Looks like I need to lower my TA again from where its at at about 70 right now. And yes I've always followed the 80-120 TA that as you say is often quoted.

I see you have a Cal Spa... how do you like it ? We just got a Cal Spa Cancun and am loving it. I don't hear too many talk about having a Cal Spa.

And THANKS again! Now I have a plan.
 

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