Can't get my pH down after a fresh fill

[jlaudadio]

Hi,

I've had my hot tub for about 6 months now and I was previously using the frog but decided I wanted to switch to the dichlor/bleach method so this weekend I drained the tub and I'm following the instructions outlined at How do I use Chlorine in my Spa (or pool)?. But I'm having a heck of time with high pH and I'm not sure what to do.

It's a 380 gallon hot tub. I'm using the Taylor K-2006 test kit.

I'm starting from a fresh fill on Saturday 11/18. I'll just give my timeline:

11/18
------
2:15pm: CH = 60, added 5oz calcium chloride dihydrate to raise it
4:30pm: CH = 120, added 2oz calcium chloride dihydrate to raise it
8:00pm: CH = 150, TA = 80, pH > 8

11/19
------
9:45am: pH > 8, added 14g dry acid to lower pH, kept pumps on after adding acid
11:30am: pH > 8, TA = 65, added 14g dry acid, kept pumps on after adding acid
12:15pm: pH > 8, added 20g dry acid, kept pumps on after adding acid
1:00pm: pH > 8, TA = 55, pumps off
6:30pm: pH > 8, added 20g dry acid, pumps on for 30 minutes after adding acid
10:15pm: pH > 8, pumps off

By this point i was getting a little suspicious of my tests so I grabbed my 5 year old, expired reagents ColorQ test kit and it read pH = 8.1. I also used some test strips and those read above 8.

11/20
------
8:15am: ph > 8, TA = 50

And that's where I'm at now. I haven't added anything else. So this is 68g (or 2.4 oz) of dry acid I've added without getting the pH under 8. My TA is now at 50 and from what I've read I shouldn't go below that number.
I will also add that the Taylor pH test kit allows me to test acid demand. It takes 2 drops to bring the test sample down to a pH of 7 which the Taylor treatment tables say amounts to 0.73 fl.oz of muriatic acid. I don't know what the equivalent is in dry acid but I don't think it could be more than what I've already added. So I'm a bit stumped. Why won't my pH come down?

Also, I have yet to add any sanitizer. It's now 2 days since I filled the tub and I don't think i should go much longer without adding some dichlor. Is there any harm in doing that now? Nobody is using the tub until I get things under control.

 

[RDspaguy]

Ok. Here we go.
Don't add calcium. Don't adjust alk unless below 50. Don't leave air control valves or water features on when not using the spa, as aeration raises ph. Let it find it's balance, you don't have anything for it to leech calcium from so it's really unimportant in a portable spa unless you use a salt system, which benefits from low calcium. Your concern is ph. It will, in my experience, be high. Higher alk will stabilize the ph fluctuation, so it is less effected by aeration, but simultaneously tends high as a result. Pick your battle. I prefer the one that doesn't have me adding contradictory chemicals in an endless and unwinnable war of financial attrition. That sounds familiar...
But I digress.
For perspective, I only own bleach and muriatic acid. And ahhsome of course, but that's different.

 

[Bperry]

Hi,

I've had my hot tub for about 6 months now and I was previously using the frog but decided I wanted to switch to the dichlor/bleach method so this weekend I drained the tub and I'm following the instructions outlined at How do I use Chlorine in my Spa (or pool)?. But I'm having a heck of time with high pH and I'm not sure what to do.

It's a 380 gallon hot tub. I'm using the Taylor K-2006 test kit.

I'm starting from a fresh fill on Saturday 11/18. I'll just give my timeline:

11/18
------
2:15pm: CH = 60, added 5oz calcium chloride dihydrate to raise it
4:30pm: CH = 120, added 2oz calcium chloride dihydrate to raise it
8:00pm: CH = 150, TA = 80, pH > 8

11/19
------
9:45am: pH > 8, added 14g dry acid to lower pH, kept pumps on after adding acid
11:30am: pH > 8, TA = 65, added 14g dry acid, kept pumps on after adding acid
12:15pm: pH > 8, added 20g dry acid, kept pumps on after adding acid
1:00pm: pH > 8, TA = 55, pumps off
6:30pm: pH > 8, added 20g dry acid, pumps on for 30 minutes after adding acid
10:15pm: pH > 8, pumps off

By this point i was getting a little suspicious of my tests so I grabbed my 5 year old, expired reagents ColorQ test kit and it read pH = 8.1. I also used some test strips and those read above 8.

11/20
------
8:15am: ph > 8, TA = 50

And that's where I'm at now. I haven't added anything else. So this is 68g (or 2.4 oz) of dry acid I've added without getting the pH under 8. My TA is now at 50 and from what I've read I shouldn't go below that number.
I will also add that the Taylor pH test kit allows me to test acid demand. It takes 2 drops to bring the test sample down to a pH of 7 which the Taylor treatment tables say amounts to 0.73 fl.oz of muriatic acid. I don't know what the equivalent is in dry acid but I don't think it could be more than what I've already added. So I'm a bit stumped. Why won't my pH come down?

Also, I have yet to add any sanitizer. It's now 2 days since I filled the tub and I don't think i should go much longer without adding some dichlor. Is there any harm in doing that now? Nobody is using the tub until I get things under control.

If you have bubbles being made, that’ll increase the pH.

 

[jlaudadio]

Ok. Here we go.
Don't add calcium. Don't adjust alk unless below 50. Don't leave air control valves or water features on when not using the spa, as aeration raises ph. Let it find it's balance, you don't have anything for it to leech calcium from so it's really unimportant in a portable spa unless you use a salt system, which benefits from low calcium. Your concern is ph. It will, in my experience, be high. Higher alk will stabilize the ph fluctuation, so it is less effected by aeration, but simultaneously tends high as a result. Pick your battle. I prefer the one that doesn't have me adding contradictory chemicals in an endless and unwinnable war of financial attrition. That sounds familiar...
But I digress.
For perspective, I only own bleach and muriatic acid. And ahhsome of course, but that's different.

If you have bubbles being made, that’ll increase the pH.

So I don't usually run the jets while I'm not using it. I know aeration increases pH. I'm just following the methodology laid out in the sticky post of this forum which calls for running the jets and adding acid until even with the jets running the pH doesn't push up to 7.8-ish. But i never got there before hitting the TA floor of 50ppm.

@RDspaguy When you say don't adjust alk unless below 50 are you saying that as long as my alk is above 50, then I should just accept whatever my pH is? In any case, i don't think the high pH is just because of a lot of aeration. For example, my reading this morning was still 8+ after the jets were turned off around 10pm the night before. One pump still runs on low speed automatically from time to time to maintain temperature and filtration, but that's it.

Seems like an 8+ pH is not where i want to be long term. What should my next move be?

 

[Bperry]

So I don't usually run the jets while I'm not using it. I know aeration increases pH. I'm just following the methodology laid out in the sticky post of this forum which calls for running the jets and adding acid until even with the jets running the pH doesn't push up to 7.8-ish. But i never got there before hitting the TA floor of 50ppm.

@RDspaguy When you say don't adjust alk unless below 50 are you saying that as long as my alk is above 50, then I should just accept whatever my pH is? In any case, i don't think the high pH is just because of a lot of aeration. For example, my reading this morning was still 8+ after the jets were turned off around 10pm the night before. One pump still runs on low speed automatically from time to time to maintain temperature and filtration, but that's it.

Seems like an 8+ pH is not where i want to be long term. What should my next move be?

pH doesn’t go down when aeration stops. I’ll have to read the sticky cause I wasn’t aware it advocated that.

 

[jlaudadio]

pH doesn’t go down when aeration stops. I’ll have to read the sticky cause I wasn’t aware it advocated that.

Here's the specific part of the sticky I'm referring to:

First, uncover your tub and turn on all your jets, air, blowers, waterfalls etc. Test your pH. When it's greater than 7.8, add enough acid to bring it down to 7.0. Keep aerating until your pH is 7.8 again (about 30 min), then add more acid and repeat. Every time you add acid you're lowering your pH and TA. When you get your TA tuned perfectly, your pH will rise to a level (i.e. ~7.6) and stop, then you know you're at your ideal TA level. If your pH is rising too high (>8.0), bring your TA down a little more. If your pH doesn't rise enough from aeration (after an hour or more), you over shot it and need to add a little Baking Soda to raise your TA.

 

[Bperry]

Here's the specific part of the sticky I'm referring to:

Interesting, that’s news to me. My understanding was that pH is never going to be perfectly stable.

 

[jlaudadio]

I was under the mistaken impression that pH would eventually drop back down after aeration stopped. After a fresh fill, the water's cold so the main pump is constantly on (low power) while it's heating the water. There's not a lot of bubbles in the water while this is happening but this is several hours a continuous movement. Plus on top of that I was keeping the jets on high power after adding acid to help mix it in. Aside from the low power on the main pump, the full jets automatically turn themselves off after 20 minutes. I would try to turn them back on but i wasn't always perfect. What I'm trying to convey is that the jets weren't running full blast for hours and hours yesterday.

 

[RDspaguy]

are you saying that as long as my alk is above 50, then I should just accept whatever my pH is?

No. I'm saying anything over 50 is fine, it's your ph you need to watch. Stop worrying about alk unless it bottoms out, it will find where it likes to be. It's your ph that's going to cause problems.

 

[DavidLast]

I was under the mistaken impression that pH would eventually drop back down after aeration stopped. After a fresh fill, the water's cold so the main pump is constantly on (low power) while it's heating the water. There's not a lot of bubbles in the water while this is happening but this is several hours a continuous movement. Plus on top of that I was keeping the jets on high power after adding acid to help mix it in. Aside from the low power on the main pump, the full jets automatically turn themselves off after 20 minutes. I would try to turn them back on but i wasn't always perfect. What I'm trying to convey is that the jets weren't running full blast for hours and hours yesterday.

As I read this I think the spa will have a higher pH. The aeration or constant movement will push the pH in an upward direction and it may be that a reading under 7.8 is not realistic. In addition, the combination of test kit accuracy, daylight and eyesight may be reading slightly out. I too wouldn't fuss too much about TA, it will be what it will be.

 

[jlaudadio]

No. I'm saying anything over 50 is fine, it's your ph you need to watch. Stop worrying about alk unless it bottoms out, it will find where it likes to be. It's your ph that's going to cause problems.

Ok, sorry if I miscommunicated this but it's not really alk i'm worried about, it's pH. The pH stays above 8 even after I've added dry acid. I have added enough dry acid that my alk has fallen to 50. My understanding is that adding acid is going to keep lowering alk so I can't add any more acid without dropping my alk below the floor of 50. So I'm not sure what to do now.

I think all the aeration has raised the pH too much. Since the tub is up to temperature now, the pumps shouldn't be on as much anymore. I think what I need to do is add baking soda to raise my TA (since i'm at 50 now) in order to give me some more room to drop the pH further with more acid. Eventually I should be able to get the pH in range with the TA somewhere above 50. Is this this the right course?

 

[mknauss]

The pH stays above 8

If the pH is above 8, the hue of the sample will be purple. Be careful you are not using the intensity of the sample as a barometer.
Try using 4 drops of reagent when testing pH. It may be better for your matching.

 

[Mdragger88]

Everybody has your ph/ta covered
To answer your other question (albeit a little late)-
Yessss, add chlorine!
Chlorine is king
You don’t have to wait to chlorinate- it’s priority #1
Ph is priority #2
Be aware of dichlor’s acidic effects before also using acid.
Use
PoolMath effects of adding to see them.

 

[jlaudadio]

If the pH is above 8, the hue of the sample will be purple. Be careful you are not using the intensity of the sample as a barometer.
Try using 4 drops of reagent when testing pH. It may be better for your matching.

It's definitely purple. I've tried fewer than 5 drops and more than 5 drops and it's always purple.
I went ahead and added some baking soda to get my TA back up to give me some more room to drop the pH and then added 2 tsp of muriatic acid (instead of dry acid) per the pool math calculator. I'll test again in a couple of hours and we'll see where I'm at.

Everybody has your ph/ta covered
To answer your other question (albeit a little late)-
Yessss, add chlorine!
Chlorine is king
You don’t have to wait to chlorinate- it’s priority #1
Ph is priority #2
Be aware of dichlor’s acidic effects before also using acid.
Use
PoolMath effects of adding to see them.

Yea, I went ahead and added some dichlor last night to get my FCL up to 3ppm.

thanks for all the responses!

 

[allanl]

Hi! I’m new here and new to hot tubs in general, but I’ve been implementing the same approach. Took a long time for me to get the pH down permanently, and I used it for a month or so at 7.8-8. Eventually alkalinity settles where it wants to.

Once you add too much acid, you’ll know! When I finally crossed the line, it dropped down to 7 fast.

The other thing I did was buy an Aperia pH probe. I’m a little red/green colorblind and got tired of asking my wife to read the strips. Hugely improved my pH control, and I can see the change in pH live. All the “wait 15 minutes” recommendations are silly (except for aeration). With jets on it’s almost instant when you add acid or baking soda.

 

[phonedave]

As a point of reference, the pH in my tub takes 7 to 10 DAYS to stabilize after fresh fill.

After a fill I check pH (and FC, CC, CYA, TA, and CH) once a day, maybe two if I am feeling especially ambitious.

I add FC in the form of DiChlor until my CYA is 30 to 40 ppm.
I add calcium for my own nefarious purposes (reducing foaming, but you can ignore it as @RDspaguy says)
I drop my pH down around 7.0 to 7.2 using MA.

Every day my pH drifts back up. I keep adding a daily dose of MA until my pH and TA come to a balance point naturally. Once that happens my pH will drift up 0.1 or so a week.

As you found out, your pH is not going to come back down after the jets turn off. Aeriation permanently increases your pH.

 

[Bperry]

As a point of reference, the pH in my tub takes 7 to 10 DAYS to stabilize after fresh fill.

After a fill I check pH (and FC, CC, CYA, TA, and CH) once a day, maybe two if I am feeling especially ambitious.

I add FC in the form of DiChlor until my CYA is 30 to 40 ppm.
I add calcium for my own nefarious purposes (reducing foaming, but you can ignore it as @RDspaguy says)
I drop my pH down around 7.0 to 7.2 using MA.

Every day my pH drifts back up. I keep adding a daily dose of MA until my pH and TA come to a balance point naturally. Once that happens my pH will drift up 0.1 or so a week.

As you found out, your pH is not going to come back down after the jets turn off. Aeriation permanently increases your pH.

I think the article referenced above might need some editing unless it really is possible to achieve a pH that is completely stable (I doubt it).

 

[DavidLast]

It's definitely purple. I've tried fewer than 5 drops and more than 5 drops and it's always purple.

Just in case...Can you run the pH test again? This time though, and I am assuming the two-bottle method, add maybe 4 drops of the clear chlorine neutralizing solution before adding the pHenol red. There are occasions when a high chlorine/bromine reading will create a purplish colour in the pH vial.

 

[JoeSelf]

What is the TA of your fill water? I'm about 120-130 depending on how much water gets added from NJ American Water. Just refilled and I'm slowly working on getting the PH stable.

We have our own wells and mix some in. When the aquafer had salt intrusion they had to get fresh water and lower the salt content.

 

[jlaudadio]

After adding baking soda to raise the TA and then dosing with 0.3 fl.oz MA followed later by 0.5 fl.oz of MA, my pH is now 7.7 and my TA is at 75! I really think I just blew up the pH on fill day between the main pump running on low all day to bring the cold water up to temperature and me running the jets for a long time while after I added the calcium to raise the CH.

Just in case...Can you run the pH test again? This time though, and I am assuming the two-bottle method, add maybe 4 drops of the clear chlorine neutralizing solution before adding the pHenol red. There are occasions when a high chlorine/bromine reading will create a purplish colour in the pH vial.

I'm not sure what you mean by the two-bottle method or the chlorine neutralizing solution. My pH test is just a single vial with some phenol red. But I doubt it's high chlorine throwing it off. I was getting these readings before I added any chlorine.

What is the TA of your fill water? I'm about 120-130 depending on how much water gets added from NJ American Water. Just refilled and I'm slowly working on getting the PH stable.

We have our own wells and mix some in. When the aquafer had salt intrusion they had to get fresh water and lower the salt content.

Fill water TA is 70 with a pH of 7.6.