Hot Tub Forum
Original => Hot Tub Forum => Topic started by: Nitro on April 22, 2009, 12:28:51 am
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This topic comes up quite a bit. I explain the process in my Maintenance Guide, but I thought I'd post a separate thread for easy reference. I won't get into detail why you would want to do this here. See my guide for more info. I will say this, the key is, you should NOT focus on adjusting pH directly. Instead, you should focus on adjusting TA to an ideal level, in order to keep your pH in line. If you're using Bleach TA should be 50-60ppm, if using Dichlor TA should be 80-100 ppm and if using Bromine TA should be 100-120 ppm.
The problem with lowering Total Alkalinity (TA) is that when you add acid to lower TA, pH also decreases. This limits the amount you can lower TA without pH becoming too low. However, there is something you can do to raise pH that leaves TA alone, Aeration. Aeration is the process of turning on all the jets and air features in your tub, in order to pump as much air into the water as possible. By adding Acid and Aerating you can lower TA, while keeping pH the same.
One thing to remember is, the amount that TA decreases is directly proportional to the amount of acid you add. That is, in a 350 gal tub, 8 oz of Dry Acid will lower TA by 100ppm. It is important to know (by calculating) how much Total Acid you need to add to your tub in order to get to your Target TA.
The other thing to remember is, the higher your TA, the less effect acid will have on your pH. If your TA is high, adding acid won't effect it much. This confuses some beginners (and experts alike), which causes them to give up on lowering their pH. Because of this, you need to add more Acid in the beginning, and less as you get closer to your Target TA.
So, let's get started. Here is the process.
1. Turn on all your jets and air features and keep them on the entire process. (i.e. Aerate)
2. Calculate how much you want to lower your TA, and how much acid you need to add to lower it.
3. Add to the tub HALF (not > 1 cup nor < 1 TBS) of the amount of the remaining acid you need to add.
4. Aerate for 30min, and check TA/pH.
5. If TA > Target and pH is > 7.8, goto step 2.
6. If TA > Target and pH is < 7.6, goto step 4 one time.
7. If TA > Target and you can't get pH > 7.8 via aeration, Target too low. Stop here.
8. If TA = Target and pH is > 7.8, Target too high. Lower Target TA and goto step 2.
Example:
Your TA is 300ppm, you want to lower it to 60ppm, in a 350 gal tub.
To lower TA by 240 ppm you need to add a total of 2.4 cups (~19oz) dry acid.
Turn jets/air on.
Add 1 cup acid and Aerate 30mins.
Check TA/pH. TA=200 and pH>8.0
Add 6 oz acid and Aerate 30mins.
Check TA/pH. TA=125 and pH>8.0
Add 3 oz acid and Aerate 30mins.
Check TA/pH. TA=90 and pH>8.0
Add 2 oz acid and Aerate 30mins
Check TA/pH. TA=65 and pH=7.8
Add 1 TBS acid and Aerate 30mins
Check TA/pH. TA=60 and pH=7.6
The main thing to remember is, you add more acid in the beginning of the process, and taper off toward the end. This method will allow you to lower your TA in a matter of a few hours regardless of how high your TA is.
Lastly, safety is priority one. Be careful with any type of acid, especially Muriatic. If you're using Muriatic acid, wear rubber gloves and eye protection. Muriatic Acid is nasty stuff. Dilute all acid in a bucket of water and slowly pour mixure over a return flow, or middle of tub. Be careful not to splash. When mixing Acid and Water, always add Acid to water! NEVER ADD WATER TO ACID!!!
Happy Tubbing! :)
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Whats you take on raising ALK without raising PH....Say a 10 ALK with a PH of 7.8.
Curious to your suggestion on this, maybe I missed it somewhere.
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Whats you take on raising ALK without raising PH....Say a 10 ALK with a PH of 7.8.
Curious to your suggestion on this, maybe I missed it somewhere.
To raise TA just add Baking Soda. It will raise TA, but won't raise pH very much. i.e. In a 400 gal tub, 1 oz BS will raise TA by ~11 ppm, but will only raise pH by ~0.02.
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To raise TA just add Baking Soda. It will raise TA, but won't raise pH very much. i.e. In a 400 gal tub, 1 oz BS will raise TA by ~11 ppm, but will only raise pH by ~0.02.
Not true!
In my 400 gallon tub I use baking soda to raise both TA and PH. I can get my TA from 80 to 120 and PH from 7.2 to 7.8 using baking soda.
In my 13,000 gallon pool - it has no effect on PH. I use borax for raising PH.
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Not true!
In my 400 gallon tub I use baking soda to raise both TA and PH. I can get my TA from 80 to 120 and PH from 7.2 to 7.8 using baking soda.
In my 13,000 gallon pool - it has no effect on PH. I use borax for raising PH.
Sorry Vinny, it is true. Chem Geek will confirm this.
The reason your pH rises in your hot tub and not your pool, is because Aeration causes pH to rise. When you add Baking Soda, only your TA rises. However, that ALLOWS pH to rise via aeration. The fact that it doesn't work the same in your pool confirms this fact. If there is little to no aeration, pH won't rise.
As I have said before, the only reason to raise TA, is if pH is too low and won't rise from aeration.
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We've had this conversation before and whenever I add baking soda my PH rises.
Besides my circ pump, my pumps only come on for 2 minutes max per day when I don't use my tub. And I don't use my tub that frequently.
I can't see how 2 minutes a day without air will cause my PH to stay at 7.8 for weeks. I use dichlor and MPS which are both adding acid to the tub's water. When I add dichlor the pumps are on for 5 minutes and with MPS for 20 minutes - again without air.
How much aeration is needed to raise the PH, keep it there and combat the effects of the dichlor and MPS? I would agree if the tub had air blowing out as well as this would be a cause for the PH to rise but IMO there's not much aeration going on in my tub.
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Raising TA will also raise pH. Try it in a pool or a hot tub or a bucket of water. It's a natural side effect.
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And some people wonder why sometimes us "newbies" have problems and get frustrated over trying to get our hot tubs properly balanced in all respects; even the "experts" don't always agree. I think I will just relax and not try to micromanage my water.....just get the readings reasonably close.
Heck, now I'm learning that trying to be too precise with the pH is not such a huge deal because it's gonna change anyway due to aeration when I use the tub............lol
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If you start with a TA of 80 ppm and a pH of 7.5 and add baking soda to raise the TA to 120 ppm, then the pH rises immediately to 7.6. Outgassing of carbon dioxide, which occurs even without explicit aeration (though more slowly) will have the pH continue to rise. So with larger increases in TA you do see a pH rise. If you start out at a lower pH, then you will see a larger pH rise of around 0.15 that may look like 0.2 (say, from 7.2 to 7.4).
Of course, if one uses sodium carbonate (pH Up) instead of sodium bicarbonate (baking soda; Alkalinity Up), then the pH rise is much larger.
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Getting back to HHT's question, the ONLY way to raise TA, without raising pH (much), is to use Baking Soda.
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And some people wonder why sometimes us "newbies" have problems and get frustrated over trying to get our hot tubs properly balanced in all respects; even the "experts" don't always agree. I think I will just relax and not try to micromanage my water.....just get the readings reasonably close.
Heck, now I'm learning that trying to be too precise with the pH is not such a huge deal because it's gonna change anyway due to aeration when I use the tub............lol
Actually, the trick is to determine who the experts really are, and ignore the rest. LOL
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Actually, the trick is to determine who the experts really are, and ignore the rest. LOL
No need to laugh at that one. That's the most accurate thing I've ever read on this forum!
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You missed my point. We have many people that have a PH of 7.7-8.0 and an ALK of 10-20, we have to raise the ALK up a lot which raises the PH up a lot,(yes I use ALK up, not PH up) even without running jets ect. We see this a lot with the water in our area...High PH with no ALK reading.
Just a little adjustment is easy, and I will have to say I see a bigger increase in PH than whats being stated, but the new tubs do have many jets and newer ozone's that produce thousands of bubbles.
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If you see the pH rise much higher than 8.0, then the baking soda may not be quite pure (it might have some sodium carbonate in it) or some outgassing occurs almost right away. When the pH is very high, say 9.0, bicarbonate will lower the pH, not raise it. The "natural" pH when adding baking soda is dependent on temperature but is in the range of around 7.8 to 8.0.
The MSDS says it's 100% sodium bicarbonate, but clearly if you are seeing a larger pH rise then there's at least a little base getting added or there's outgassing (bubbling) that happens very quickly, perhaps during addition since the TA is very high locally when you are adding it (i.e. some carbon dioxide outgasses right away). That's probably the explanation and would account for most people's experience when they add baking soda. That would mean that the way it is mixed would make some difference.
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If you see the pH rise much higher than 8.0, then the baking soda may not be quite pure (it might have some sodium carbonate in it) or some outgassing occurs almost right away. When the pH is very high, say 9.0, bicarbonate will lower the pH, not raise it. The "natural" pH when adding baking soda is dependent on temperature but is in the range of around 7.8 to 8.0.
The MSDS says it's 100% sodium bicarbonate, but clearly if you are seeing a larger pH rise then there's at least a little base getting added or there's outgassing (bubbling) that happens very quickly, perhaps during addition since the TA is very high locally when you are adding it (i.e. some carbon dioxide outgasses right away). That's probably the explanation and would account for most people's experience when they add baking soda. That would mean that the way it is mixed would make some difference.
Might make a difference if people stopped putting baking and other house hold products in their hot tub, too.
Funny, you never see anyone baking a cake with TA Increaser. ::)
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First, I will say that HOWEVER PH gets increased - it does. To say that baking soda does not increase PH was wrong and I believe chem geek "proved" that.
Considering that 0.15 is a number close to the next PH number vs 0.02 - I stand firm on what I've said. I have added approximately 2 oz if my PH is 7.2 to 4 oz if I didn't catch it before dipping below 7.0 and it will go to about 7.8. I don't care if it not the correct way to get there - it gets there!
Second, I am by far an expert but have done a lot of reading and experimenting and try to get as knowledgeable as I can for my own good. I know what works for my water but I don't know it all and have asked others about problems for both my pool water and my spa water. I personally try not to give "because I said so" answers as some do on other websites. Knowledge is the key to understanding.
Third, TubsAndCues, sodium bicarb is just that. If a spa alkalinity up is sodium bicarb there is no difference in the $0.79 box in the grocery store or the $9.99 bottle in a retail store. Most of the ingredients that I have read on these is sodium bicarb. Powder is powder and I would think and hope that food grade bicarb is closer to pure than spa or pool grade bicarb.
Fourth, Hillbilly Hot Tub, the most that PH can go to by adding bicarb is 8.4 (I think thats what it's PH is). Since I have no practical experience I can only think that the way to do what you ask is to raise the alkalinity to above the reading you want and then hit it with PH down until both readings are in range. Maybe it's reversed - lower PH and then bring alkalinity up. Sorry, I have the perfect water for the spa - low PH and alkalinity.
Lastly, kokanee001, as a once newbie I can tell you that most of us do/did micromanage the water. If you look at the watergram that comes in the Taylor kits - everything is a range. You don't need 3 PPM chlorine, you can have more but 3 is the minimum; the last thing Taylor has you check/balance is the PH and it's based on the temp of the water and it tells you that any reading that's in +/- 0.5 reading of the PH is OK and the water is balanced. There are 2 major theories in water balancing that are popular and I'm not sure which Taylor uses - so you see it's not an exact science.
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Considering that 0.15 is a number close to the next PH number vs 0.02 - I stand firm on what I've said. I have added approximately 2 oz if my PH is 7.2 to 4 oz if I didn't catch it before dipping below 7.0 and it will go to about 7.8. I don't care if it not the correct way to get there - it gets there!
Fourth, Hillbilly Hot Tub, the most that PH can go to by adding bicarb is 8.4 (I think thats what it's PH is). Since I have no practical experience I can only think that the way to do what you ask is to raise the alkalinity to above the reading you want and then hit it with PH down until both readings are in range. Maybe it's reversed - lower PH and then bring alkalinity up. Sorry, I have the perfect water for the spa - low PH and alkalinity.
2 ounces weight of baking soda in 350 gallons raises the TA by about 25 ppm while 4 ounces weight raises it by about 51 ppm (by volume, 2 ounces raises TA by about 32 ppm, 4 ounces by about 64 ppm). These are rather large increases in TA (at least 50 is). The pH starting at 7.2 would rise to around 7.4 depending on starting TA so if you see it going to 7.8 almost immediately after addition then that could happen if around 0.2 ounces of carbon dioxide were to outgas. It seems reasonable to me that this could happen during the baking soda addition since the TA is extremely high where you add it until it gets diluted and outgassing is very dependent on TA level (even more so than on pH). The problem is that this isn't reliable or predictable since it should depend somewhat on how the baking soda is added and mixed with the water. Also, you clearly get a large increase in TA so if you want to increase the pH without such a rise then this wouldn't be the way to do it (you'd either use Borax or aerate instead).
I think that Nitro's point is that if you have a somewhat consistent type of tub usage including type of chlorine and amount of aeration, then there is a TA level that will roughly result in a fairly steady pH over time. When using Dichlor, this means a small addition of baking soda is needed over time. For example, with 2 teaspoons per day Dichlor usage, approximately 1/2 teaspoon of baking soda would compensate for the resulting TA loss and there is a TA level such that the pH will stay fairly constant after such combination of chemical additions and outgassing. To make things simple, one should focus on adjusting the TA level until their pH gets stable and not mistakenly think that increasing TA always does that -- sometimes a lower TA is more stable and this is especially true when using bleach instead of Dichlor. When using bleach, if one gets to stable pH at a lower TA level, then neither acid nor baking soda will need to be added -- in practice, one usually needs to add a small amount of both periodically.
The pH I quoted earlier from adding baking soda that tends to go to 7.9 or 8.0 is at spa temps. At that pH an equal amount of bicarbonate goes to carbonate and to carbonic acid (actually, that's at around pH 8.1, but with calcium in the water some of the ions form ion pairs with the calcium so shift things a little bit) so the pH doesn't change -- it's not 8.4, though I've heard that quoted before. I can calculate 8.4 for pH from baking soda if it's added to distilled water at a cooler temperature of 20C (68F). A pH of 8.4 (at a TA of around 85 ppm) is also the pH where there is in equilibrium between the carbon dioxide in the air and in the water so outgassing would completely stop at that point. Pools and spas are intentionally over-carbonated in order to provide a pH buffer and (for pools, mostly) to saturate the water with calcium carbonate to prevent dissolving of plaster/gunite/grout. TA is mostly a measure of that carbonation, mostly as bicarbonate.
Richard
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Fourth, Hillbilly Hot Tub, the most that PH can go to by adding bicarb is 8.4 (I think thats what it's PH is). Since I have no practical experience I can only think that the way to do what you ask is to raise the alkalinity to above the reading you want and then hit it with PH down until both readings are in range. Maybe it's reversed - lower PH and then bring alkalinity up. Sorry, I have the perfect water for the spa - low PH and alkalinity.
I have always lowered the PH/ALK to about 7.0 then brought the Alk back up. I was told this is called slugging and should not be done, its "old School" so I was wondering what others takes may be on it.
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Richard, the 8.4 is what I remember from Chemistry class. I've never actually measured it.
Hillbilly Hot Tub, I've only read on what to do but is old school so bad? I don't believe there's a perfect way to adjust anything.
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Unless someone has a better way, it works for me! :)
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Living in Southern Cal, I seldom get a call to adjust TA without also needing to adjust pH at the same time. They tend to go up and down together, and adding a bit of Spa Down takes care of 99 out of 100 of my customers. I try to keep things a simple as I can.
If I do get a call from somebody who has a high TA and low pH, I usually suggest they drain and refill the tub. Much easier - and may take less time as well. If they have just refilled, I suggest they bring in a sample and I do a work-up on the water lab. But most of the time I find out they used a strong cleaner/cleanser during the water change, and they will need to drain and refill anyway.
Water is the cheapest chem you can add to a tub. Keep the chem maintenance simple for best results.
8-)
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Living in Southern Cal, I seldom get a call to adjust TA without also needing to adjust pH at the same time. They tend to go up and down together, and adding a bit of Spa Down takes care of 99 out of 100 of my customers. I try to keep things a simple as I can.
Here in the Chicago area, people who have lake water have it great (TA=100 ppm and pH=7.5). TA still has to lower if using the Dichlor/Bleach method. Otherwise, they can leave it alone.
However, there are still a lot of people outside Cook/Lake country who have well water with really high TA levels (400-500 ppm). Their only options are to use this method, or have their water trucked in.
If I do get a call from somebody who has a high TA and low pH, I usually suggest they drain and refill the tub. Much easier - and may take less time as well. If they have just refilled, I suggest they bring in a sample and I do a work-up on the water lab. But most of the time I find out they used a strong cleaner/cleanser during the water change, and they will need to drain and refill anyway.
Again that wouldn't work if your source water is high in TA.
Water is the cheapest chem you can add to a tub. Keep the chem maintenance simple for best results.
I totally agree! And the less you put into your tub water the better.
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Hello there, this for him of lowering total alkalinity without changing pH was very useful to me with my situation. Could you please tell me on what acid to use to lower total alkalinity? Thanks
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To get back on point - another facet to remember when lowering TA or pH, if you add the product to calm, still water and allow it to sit for, say, 30-60 mins, and then turn on the jets, the reducing agent is more effective. If adding to a pool - you want to add the product to the deep end, and let sit overnight. In the morning, turn the pump back on and re-test after a few hours.
This is a great tip that I have applied to the hot tubs I test and it really does increase the effectiveness of Sodium Bisulfate or Muriatic Acid. I hope this helps. Good luck moving forward.