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Having Trouble With Ph And Alkalinity ......


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#1 bart6453

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Posted 09 May 2009 - 07:17 AM

This is a total stupid question but I am having an issue keeping my TA down and my PH down...I have never had a tub before and got it going this week. I am using Dichlor and a full line of chemicals from Proteam.

My TA is staying around 150ppm and my PH will temporarily lower to 7.5, but then in a few hours it will jump back up to 8.0 or so and my alkalinity will stay at 150ppm. So when I add PH down....it lowers the ph....but my TA still stays around 150ppm. How the heck do I lower the TA?
Is this something that will happen as the tub gets used more?????

I have been using the tub a bit, maybe an hour a day...1-2 people who are fairly clean...and have been using the bubblers...which I understand will increase the PH on their own. The question really is that do I have to keep using that much PH down? I just have no idea about what the usage really is on chemicals...thus far I have added about 28oz of PH down to a 400 gallon tub in the span of 4 days.

Thanks, Bart
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#2 chem geek

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Posted 09 May 2009 - 09:03 AM

Bart,

Something doesn't make sense here. Though the pH going up makes sense due to the higher TA and aeration, the TA should go down when you add acid, especially adding as much pH Down as you have described.

Are you using test strips? They are not always accurate and perhaps the TA strips have gone "bad". The best test kit to get is the Taylor K-2006 you can get at a good online price here or the TF100 test kit from tftestkits.net here with the latter kit having 36% more volume of reagents so is less expensive per test.

Have you been inadvertently adding any other chemicals to your tub that perhaps contained sodium bicarbonate (baking soda; Alkalinity Up) or sodium carbonate (washing soda; pH Up)? Is the pH Down product you are using 93.2% sodium bisulfate -- what does it say for the ingredients on the bottle?

Richard

#3 bart6453

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Posted 09 May 2009 - 09:16 AM

The test kit is a HTH 6 way liquid type with the tinting agents and reagents...brand new by the way.

As to other chemicals...I have added nothing but dichlor and Gentle spa. With that said our area has high TA and PH out of the faucet.

The PH down is as follows:

Directions from the bottle

Application

Proper pH should range between 7.4-7.6

Use 1 ounce to lower pH .1 per 100 gallons of spa or hot tub water

To avoid lowering Total Alkalinity dilute 1 ounce into 10 ounces of spa or hot tub water in container and pour evenly around spa or hot tub

Should Total Alkalinity need lowering simultaneously as pH correction, pour appropriate amount directly into spa or hot tub water in one area without dilution with pump and filter turned off

Available Size 1 qt. bottle (12 per case)

Ingridents from the MSDS sheet:

2. Composition and Information on Ingredients
Ingredient CAS Number Weight % ACGIH TLV PEL STEL
Hydrochloric acid 7647-01-0 5 ppm ceiling 5 ppm ceiling

thanks for your help!!!!!

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#4 Nitro

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Posted 09 May 2009 - 11:12 AM

Hi Bart,

You shouldn't try controlling pH directly. Instead, you need to find the right TA level that will keep pH balanced. If you lower your TA to around 80-100 ppm, that should keep your pH in line. If your pH still creeps up, lower TA more. If you find your pH staying too low, raise your TA a little.

By the amount that you already added, your TA must have been up around 380 ppm. Have you checked you tap water directly? Approx. 12 oz Dry Acid (pH Down) will lower your TA by around 100 ppm. So it sounds like you still need to add ~6 oz Dry Acid. Check out my Lowering TA link below for more info.

Nitro's Approach To Water Maintenance
A guide to Water Balance and Sanitation using Chlorine

Lowering Total Alkalinity
How to lower TA, without lowering pH

Chlorine Demand (CD)
What is it, and why you should care

Decontamination
How to Super Shock your Tub

#5 bart6453

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Posted 09 May 2009 - 11:17 AM

QUOTE (Nitro @ May 9 2009, 02:12 PM) <{POST_SNAPBACK}>
Hi Bart,

You shouldn't try controlling pH directly. Instead, you need to find the right TA level that will keep pH balanced. If you lower your TA to around 80-100 ppm, that should keep your pH in line. If your pH still creeps up, lower TA more. If you find your pH staying too low, raise your TA a little.

By the amount that you already added, your TA must have been up around 380 ppm. Have you checked you tap water directly? Approx. 12 oz Dry Acid (pH Down) will lower your TA by around 100 ppm. So it sounds like you still need to add ~6 oz Dry Acid. Check out my Lowering TA link below for more info.



Great thanks.....so do you think one should not use the liquid PH down??? The kind I have been using is a liquid hydrocloric acid solution. Is it better to use the powder type?

thanks again!!!! BART


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#6 chem geek

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Posted 09 May 2009 - 12:05 PM

The ProTeam pH Down (for spas) has an MSDS here and doesn't give the percentage of hydrochloric acid -- do you see a percentage on the ingredients list on the bottle itself? The guide to use 1 ounce to lower the pH by 0.1 in 100 gallons is pretty useless since it depends on the TA level, whether you have Borates (Proteam Gentle Spa) and on the starting pH. Using typical mid-range numbers and without Borates, I'm guessing that this is a 2% hydrochloric acid solution in pH Down.

In 400 gallons, 28 ounces would lower the TA (when measured at the same pH before and after) by 17 ppm. Perhaps the pH Down is only a 1% solution in which case the TA would only drop by around 8-9 ppm which wouldn't be particularly noticeable.

The high TA in your initial fill water should only affect the initial water balance. I assume you don't have a lot of refill from evaporation, do you?

Forget their instructions of how to lower pH vs. TA separately -- it's bunk. When you add acid, it lowers BOTH pH and TA. The amount that pH gets lowered depends on several factors including starting pH, TA level, and whether there are borates in the water. The amount that the TA gets lowered, however, is only dependent on the amount of acid that gets added. Then, subsequent outgassing of carbon dioxide from the water (sped up by more aeration, such as spa jets, and at lower pH and higher TA) raises the pH with no change in TA.

If you want to lower the TA in your spa, you would follow the procedure described in this post, but all this does is accelerate the process -- the total amount of acid needed is the same regardless of whether you get this over with quickly by following the procedure vs. just adding acid over time. The difference is that by getting it over with all at once, you don't have to add acid as frequently (nor as much) in the future until the next refill.

Though you could continue to use Proteam products -- Gentle Spa is a great source for Borates -- you could get more concentrated sources of pH Down, such as dry acid (from a pool store or big-box store that sells pool chemicals or use Proteam pH Down for pools) or half-strength (15%) hydrochloric acid (from a hardware or big-box store). I just suspect that you are paying a lot for a very weak acid.

Richard

#7 Nitro

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Posted 09 May 2009 - 12:15 PM

QUOTE (bart6453 @ May 9 2009, 02:17 PM) <{POST_SNAPBACK}>
Great thanks.....so do you think one should not use the liquid PH down??? The kind I have been using is a liquid hydrocloric acid solution. Is it better to use the powder type?

thanks again!!!! BART

Oops, my mistake! I didn't catch that you were using Muriatic Acid. I thought you were using Dry Acid. You can use Muriatic Acid, since you have it. Just be careful, it's nasty stuff. Wear eye protection, and rubber gloves.

Assuming it's 31%, that means 10 oz will lower your TA by 100 ppm. That means your TA was around 430 ppm when you started. So you need to add another 5 oz total to lower your TA 50 ppm from 150 to 100 ppm. However, I would follow the procedure in my link below for lowering TA, so your pH doesn't get too low.

Exmaple:
Add 2 oz and aerate for 30 mins.
Check TA/pH
Add 2 oz and aerate for 30 mins.
Check TA/pH
Add 1 oz and aerate for 30 mins.
Check TA/pH

If your pH is still high (>7.8), add another oz and aerate for 30 mins.
Continue until your pH stays around 7.6-7.8 after aerating. You should be good to go.

Lastly, if you're using Dichlor and/or MPS (Non-Chlorine Shock), your TA will continue to drop, because they're acidic. So you may need to raise TA some time in the future by adding Baking Soda. Just keep an eye on your pH. If you find it creeping down, then you know your TA is too low. Likewise, if you find it creeping up, then you know your TA is too high.

Make sense?
Nitro's Approach To Water Maintenance
A guide to Water Balance and Sanitation using Chlorine

Lowering Total Alkalinity
How to lower TA, without lowering pH

Chlorine Demand (CD)
What is it, and why you should care

Decontamination
How to Super Shock your Tub

#8 Nitro

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Posted 09 May 2009 - 12:23 PM

Chem geek makes a good point (as usual). Your acid could be weak (1-2%), which throws off my calculations above.

First, I would try to find out the percentage of that Acid.

Second, measure the TA of your source water. That will tell us approx how much 28 oz of the acid lowered your TA by how much. We can then estimate the percentage of the Acid.

Third, as Chem Geek said, if that acid turns out to be weak, I would just buy Dry Acid from now on. No point in paying extra for less.
Nitro's Approach To Water Maintenance
A guide to Water Balance and Sanitation using Chlorine

Lowering Total Alkalinity
How to lower TA, without lowering pH

Chlorine Demand (CD)
What is it, and why you should care

Decontamination
How to Super Shock your Tub

#9 bart6453

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Posted 09 May 2009 - 12:59 PM

This is great info guys...I suspected that my acid was fairly weak.....I have some dry pH down sitting outside the closed pool supply shop waiting for me to get off work!!!!

thanks again....looks like I have this one under control now...add some dry acid....aerate.....an should be rocking in no time!


Later,
BART
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#10 bart6453

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Posted 09 May 2009 - 04:16 PM

the 17PPM reduction is just about exactly what I ended up with....so I am not crazy! It just seemed like so much product for so little change, why would they have a product like that????

I have started the sequence of figuring out the exact theoretical amount of dry acid, halving it and aerating for 30 minutes. My PH has risen slightly but the TA has dropped at exactly the calculated amount. Is it possible that different tubs aerate at different levels creating a PH rise with this method? On that thought I am still in process but turned 2 of my 3 aeration circuits off.

Thanks for all the help...this is awesome that with your information I can get theoretical results and actual results to nearly match.

It's gonna be okay....trust me!

#11 Nitro

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Posted 09 May 2009 - 05:43 PM

QUOTE (bart6453 @ May 9 2009, 07:16 PM) <{POST_SNAPBACK}>
the 17PPM reduction is just about exactly what I ended up with....so I am not crazy! It just seemed like so much product for so little change, why would they have a product like that????

I have started the sequence of figuring out the exact theoretical amount of dry acid, halving it and aerating for 30 minutes. My PH has risen slightly but the TA has dropped at exactly the calculated amount. Is it possible that different tubs aerate at different levels creating a PH rise with this method? On that thought I am still in process but turned 2 of my 3 aeration circuits off.

Thanks for all the help...this is awesome that with your information I can get theoretical results and actual results to nearly match.

FYI, the amount of dry acid you add doesn't have to be exactly half the total. The main point is to add more in the beginning, and less at the end. This is because if you have a high inital TA (300-400), you can bring it down faster without it taking forever. I came up with this method (adding half each time), because I find if you tell someone to add acid until pH drops to 7.0 is not enough information. The amount of acid needed to lower pH to 7.0 will vary largely based on the current TA level. But if you use my method, you know exactly how much acid to add each time to lower TA in the fastest time, and in the safest manner.

Also, every tub aerates by different amounts. That's why you need to TUNE your TA for your own tub. Think of TA as your control knob, for setting pH to ~7.5. Once you understand this consept (and how to adjust TA), balancing your water becomes a no brainer, regardless of your initial TA.
Nitro's Approach To Water Maintenance
A guide to Water Balance and Sanitation using Chlorine

Lowering Total Alkalinity
How to lower TA, without lowering pH

Chlorine Demand (CD)
What is it, and why you should care

Decontamination
How to Super Shock your Tub

#12 bart6453

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Posted 09 May 2009 - 07:58 PM

That's great info too.....I figured it was more of a guide line....kind of like slowing to a stop sign.....you apply the brakes harder and gradually let off as you come to a stop.

The aeration is kind of interesting too....now I know how people can have real trouble with a tub. I am no moron but there is clearly a steep learning curve and if you are not paying attention you could surely hurt yourself or others. If one were to be less fastidious about the water quality of their tub it could be a disaster!

In the end I was able to lock my TA in at 90ppm with a PH of 7.5....I figured that should be pretty much on the nutz.

Thanks for all your help...this is awesome...now after 25 years I finally know why my parent's tub always sucked.
It's gonna be okay....trust me!

#13 adamslucky13

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Posted 17 May 2009 - 06:02 AM

We purchase our spa in October. We are using eco one products. We didn't get good instructions about the water chemistry when it was delivered. After initially using the Spa Monthly, the first time we got in our hottub there was grit all over the walls. We just got in and wiped it down with our hands and didn't have the problem anymore.

About 2 weeks ago, we drained cleaned and filled the hottub. Long story short, same grit but we didn't wipe it down right away. AFter about 4 days, the grit had hardened on the walls. Then after consulting with someone from Pacific Sands Inc (eco one people) hey asked us how the water tested. We were never told to test the water. I know, sounds strange but very true. I couldn't get the right balance so we decided to drain the spa because we HAD to clean that scale off the walls. We have extremely hard water here. The only thing that would cut it was ALOT of elbow grease and vinegar. I took a sample to have it analyized and was told to fill the spa from our water softener, which we hadn't done before. We just filled it and I've been trying to get my chemistry to balance and cannot get my pH balanced. Everything else looks good. I just got it pretty close and I'm so frustrated with it so since it was close, I went ahead and dumped in spa monthly. I was also told to use 3 packets of oneshock after that cycles through. Someone please help me! My water is very clear. I never knew this was going to be so hard. How importing is it to have the water test and match perfectly with those strips because I just can't seem to get the perfect reading. I get PINK or light orange. From one extreme to the other it seems!! It's Sunday so I'm getting no service no matter where I call. Someone please help!!!

#14 Nitro

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Posted 17 May 2009 - 12:23 PM

QUOTE (adamslucky13 @ May 17 2009, 09:02 AM) <{POST_SNAPBACK}>
We purchase our spa in October. We are using eco one products. We didn't get good instructions about the water chemistry when it was delivered. After initially using the Spa Monthly, the first time we got in our hottub there was grit all over the walls. We just got in and wiped it down with our hands and didn't have the problem anymore.

About 2 weeks ago, we drained cleaned and filled the hottub. Long story short, same grit but we didn't wipe it down right away. AFter about 4 days, the grit had hardened on the walls. Then after consulting with someone from Pacific Sands Inc (eco one people) hey asked us how the water tested. We were never told to test the water. I know, sounds strange but very true. I couldn't get the right balance so we decided to drain the spa because we HAD to clean that scale off the walls. We have extremely hard water here. The only thing that would cut it was ALOT of elbow grease and vinegar. I took a sample to have it analyized and was told to fill the spa from our water softener, which we hadn't done before. We just filled it and I've been trying to get my chemistry to balance and cannot get my pH balanced. Everything else looks good. I just got it pretty close and I'm so frustrated with it so since it was close, I went ahead and dumped in spa monthly. I was also told to use 3 packets of oneshock after that cycles through. Someone please help me! My water is very clear. I never knew this was going to be so hard. How importing is it to have the water test and match perfectly with those strips because I just can't seem to get the perfect reading. I get PINK or light orange. From one extreme to the other it seems!! It's Sunday so I'm getting no service no matter where I call. Someone please help!!!

It sounds like your TA/pH is high, and causing scaling (Calcium Deposts).

First, check out my guide below, the Water Balance section for more info on how to balance your water. Also, check out the Lowering TA link.

Second, I'd forget about using guess(test) strips to test your water, or you'll continue to have problems. Get a good drop test kit such as the Taylor K-2006 for Chlorine, or K-2106 for Bromine.

Lastly, and my humble opinion, I would look into another sanitation method using Chlorine or Bromine. I think you'll find them easier, cheaper and safer.

Help that helps.
Nitro's Approach To Water Maintenance
A guide to Water Balance and Sanitation using Chlorine

Lowering Total Alkalinity
How to lower TA, without lowering pH

Chlorine Demand (CD)
What is it, and why you should care

Decontamination
How to Super Shock your Tub

#15 Nitro

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Posted 17 May 2009 - 01:21 PM

Adam,

I forgot to mention, you can clean the scale off the spa shell by lowering your TA/pH below normal, and let it sit for a few days. That will cause the Cacium to go back into the water.
Nitro's Approach To Water Maintenance
A guide to Water Balance and Sanitation using Chlorine

Lowering Total Alkalinity
How to lower TA, without lowering pH

Chlorine Demand (CD)
What is it, and why you should care

Decontamination
How to Super Shock your Tub




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