Frustrating Ph Vs Ta Issue

[ncspa]

A bit back I wrote in about a frustrating pH vs. TA issue I've been having. In a nutshell, my TA is low (about 50) and my pH is high (about 8) [if it's relevant, this is a brand new Marquis Reward that has been up and running for a few weeks now. Fiberglass shell, etc. so no grout issues. Ozonator installed. Also no water quality issues in the area, city water, etc. etc.]. Also, all tests are done with a Taylor 2105

So, I tried to shoot my TA way up so that I could bring the pH down with small additions of acid. I used pH up (baking soda) to bring the TA to about 85. Then, I slowly added dry acid, about .5 oz at a time over several days. Of course, TA began to drop but pH hung right in there! So, I now have TA back to about 50 and pH still about 8.0.

My question is - should I leave well enough alone? Seems fairly stable at this point. Is 50 low enough and/or 8.0 high enough to be of concern?

For what it's worth, no help locally. Pool store tells me to bring up TA then deal with pH, which I did. My dealer, unfortunately, just uses the test strips and he tells me things are fine (of course, the strip looks like 7.8, or maybe 7.6 - hell, who can tell?!!) - but, in fact, Taylor kit is telling me 8.0. Great dealer otherwise - disappointing that he uses the strips.

Sure appreciate the help from those of you in the know.

[Chris W]

By chance do you have high calcium in your water? It has been my experience that in water with high calcium, the Alk has to be quite low before the pH starts reacting "normally" when making adjustments.

Another possiblity is that the level of aeration in your spa is driving the pH up. Are you leaving the air controls open all the time? You might try keeping the air controls closed all of the time except when you are using the tub.

Chris W

[ncspa]

By chance do you have high calcium in your water? It has been my experience that in water with high calcium, the Alk has to be quite low before the pH starts reacting "normally" when making adjustments.

Another possiblity is that the level of aeration in your spa is driving the pH up. Are you leaving the air controls open all the time? You might try keeping the air controls closed all of the time except when you are using the tub.

Chris W

No - in fact, my calcium is a little on the low side. Air is not controlled with this tub - some comes in with the jets automatically, but not much. Otherwise no air valves.

Thanks - other thoughts?

[Chris W]

I re-read your 1st note. To start with, pH Up (Sodium Carbonate) is NOT used to bring alkalinity up. It's primary effect is on pH. Sodium BIcarbonate (baking soda, 40 cents a pound at the grocery store) is used to bring Alkalinity up. This could be a big part of the issue, sorry I missed it before. I'd add the baking soda to get the alkalinity back up and if the pH needs to come down, bring it down with acid. The acid will likely bring the Alkalinity back down some, but you should start making progress.

Also, what are you using as a sanitizer? With Chlorine, I target a little lower pH for more effectives sanitization.

Chris W

[ncspa]

I re-read your 1st note. To start with, pH Up (Sodium Carbonate) is NOT used to bring alkalinity up. It's primary effect is on pH. Sodium BIcarbonate (baking soda, 40 cents a pound at the grocery store) is used to bring Alkalinity up. This could be a big part of the issue, sorry I missed it before. I'd add the baking soda to get the alkalinity back up and if the pH needs to come down, bring it down with acid. The acid will likely bring the Alkalinity back down some, but you should start making progress.

Also, what are you using as a sanitizer? With Chlorine, I target a little lower pH for more effectives sanitization.

Chris W

Look again my friend. pH up is indeed sodium bicarbonate (otherwise known as Sodium Hydrogen Carbonate = same thing). Anyway, that's what I use.

Thanks for taking a closer look, but the problem remains! Actually, found today that the pH had dropped to 7.6 using the acid (hurrah!) but my TA was down to 40 (bummer). May just leave it that way awhile and see what happens.

[fdegree]

My water tends to keep a high pH...usually around 7.8. At the advice posted in this forum, I have kept my TA low...usually around 40 - 60. I don't increase the TA until it reaches 30. I am thinking this may be due to the fact we don't use the spa as frequently as we did when we first got it, because the water chemistry was different the first 2 months after we got the spa. Now, I am dealing with this low TA and high pH issue.

Here is a link to a discussion on this topic. Maybe it will help.

[Jim_The_Jim]

A bit back I wrote in about a frustrating pH vs. TA issue I've been having. In a nutshell, my TA is low (about 50) and my pH is high (about 8) [if it's relevant, this is a brand new Marquis Reward that has been up and running for a few weeks now. Fiberglass shell, etc. so no grout issues. Ozonator installed. Also no water quality issues in the area, city water, etc. etc.]. Also, all tests are done with a Taylor 2105

So, I tried to shoot my TA way up so that I could bring the pH down with small additions of acid. I used pH up (baking soda) to bring the TA to about 85. Then, I slowly added dry acid, about .5 oz at a time over several days. Of course, TA began to drop but pH hung right in there! So, I now have TA back to about 50 and pH still about 8.0.

My question is - should I leave well enough alone? Seems fairly stable at this point. Is 50 low enough and/or 8.0 high enough to be of concern?

For what it's worth, no help locally. Pool store tells me to bring up TA then deal with pH, which I did. My dealer, unfortunately, just uses the test strips and he tells me things are fine (of course, the strip looks like 7.8, or maybe 7.6 - hell, who can tell?!!) - but, in fact, Taylor kit is telling me 8.0. Great dealer otherwise - disappointing that he uses the strips.

Sure appreciate the help from those of you in the know.

The pH is primary, the TA is a tool for controling pH. Lower the pH and let the TA go for now. The TA is used to contol pH, but if you are using only chlorine, and or chlorine shock you will get a high pH and low TA all the time. If you can get the pH to stabilize with a TA of 30 that is fine, but it will probably start to fall, then you can slowly raise the TA and pH. If you are using chlorine you need to keep the pH around 7.2 because it is not effective at high pH.

http://www.soundclick.com/havenhead

[ncspa]

I re-read your 1st note. To start with, pH Up (Sodium Carbonate) is NOT used to bring alkalinity up. It's primary effect is on pH. Sodium BIcarbonate (baking soda, 40 cents a pound at the grocery store) is used to bring Alkalinity up. This could be a big part of the issue, sorry I missed it before. I'd add the baking soda to get the alkalinity back up and if the pH needs to come down, bring it down with acid. The acid will likely bring the Alkalinity back down some, but you should start making progress.

Also, what are you using as a sanitizer? With Chlorine, I target a little lower pH for more effectives sanitization.

Chris W

Look again my friend. pH up is indeed sodium bicarbonate (otherwise known as Sodium Hydrogen Carbonate = same thing). Anyway, that's what I use.

Thanks for taking a closer look, but the problem remains! Actually, found today that the pH had dropped to 7.6 using the acid (hurrah!) but my TA was down to 40 (bummer). May just leave it that way awhile and see what happens.

Oops - my apologies! I was checking my bottle of "pH / Alkalinity Up". In any event, it has been the baking soda that I've been using again. Thanks again for the input

[ncspa]

My water tends to keep a high pH...usually around 7.8. At the advice posted in this forum, I have kept my TA low...usually around 40 - 60. I don't increase the TA until it reaches 30. I am thinking this may be due to the fact we don't use the spa as frequently as we did when we first got it, because the water chemistry was different the first 2 months after we got the spa. Now, I am dealing with this low TA and high pH issue.

Here is a link to a discussion on this topic. Maybe it will help.

Thanks for the link - I'd been following that thread but hadn't gotten back to it.

One thing I'll add (for anyone that's in a similar situation) - using unfiltered light when interpreting the Taylor kits is really important. I'd been doing my testing mostly at night after work, and apparently the artificial indoor lighting in my kitchen has been making the readings appear slightly higher than they are, even with a white background. I tried testing in natural light this weekend and found my readings slightly lower. Same problem remains (TA at ~40-50) with high pH, but it's more like 7.8-7.9 than 8.0+ (which I thought was where I was).

Keep me posted on your issues. Sounds like we use the tub quite a bit more (usually everyday) than you, so outgassing is a big problem for us - definitely raises the pH, but doesn't seem to take the alkalinity with it. Anyway, here's hoping we both get it solved!

[fdegree]

Thanks for the link - I'd been following that thread but hadn't gotten back to it.

One thing I'll add (for anyone that's in a similar situation) - using unfiltered light when interpreting the Taylor kits is really important. I'd been doing my testing mostly at night after work, and apparently the artificial indoor lighting in my kitchen has been making the readings appear slightly higher than they are, even with a white background. I tried testing in natural light this weekend and found my readings slightly lower. Same problem remains (TA at ~40-50) with high pH, but it's more like 7.8-7.9 than 8.0+ (which I thought was where I was).

Keep me posted on your issues. Sounds like we use the tub quite a bit more (usually everyday) than you, so outgassing is a big problem for us - definitely raises the pH, but doesn't seem to take the alkalinity with it. Anyway, here's hoping we both get it solved!

At this point in my hot tub endeavor (only 6 months in), I don't have plans to remedy what I am doing (I want to use as few chemicals as possible). I realize things are not in the ideal range, but I have come to trust Chem Geek's advice. If I am interpreting his posts correctly, what I am doing is not really that big of a problem...it is not perfect, but also not so far out of whack that I have to worry about developing problems. I test the water about once a week, and since we don’t use the spa that much it seems to stay fairly steady. If our usage ever increases, I will then have to be more diligent with my testing and treating. So, right now, I’m not overly concerned.

In fact, I just tested my water today:

TA = 40

pH = 7.6

Br = 4.0

I did nothing...when the TA hits 30; I'll add baking soda to get it up to 60. Usually, baking soda is the only chemical I add, after my initial balancing of my fill water, for the life of that fill (with the exception of the bromine floater). So, only adding baking soda about once a month for the 3 - 4 month fill seems fairly safe to me.

Good luck with your situation. If you get it where you want it, it will be nice to hear how you made that happen.

[ncspa]

Thanks for the link - I'd been following that thread but hadn't gotten back to it.

One thing I'll add (for anyone that's in a similar situation) - using unfiltered light when interpreting the Taylor kits is really important. I'd been doing my testing mostly at night after work, and apparently the artificial indoor lighting in my kitchen has been making the readings appear slightly higher than they are, even with a white background. I tried testing in natural light this weekend and found my readings slightly lower. Same problem remains (TA at ~40-50) with high pH, but it's more like 7.8-7.9 than 8.0+ (which I thought was where I was).

Keep me posted on your issues. Sounds like we use the tub quite a bit more (usually everyday) than you, so outgassing is a big problem for us - definitely raises the pH, but doesn't seem to take the alkalinity with it. Anyway, here's hoping we both get it solved!

At this point in my hot tub endeavor (only 6 months in), I don't have plans to remedy what I am doing (I want to use as few chemicals as possible). I realize things are not in the ideal range, but I have come to trust Chem Geek's advice. If I am interpreting his posts correctly, what I am doing is not really that big of a problem...it is not perfect, but also not so far out of whack that I have to worry about developing problems. I test the water about once a week, and since we don’t use the spa that much it seems to stay fairly steady. If our usage ever increases, I will then have to be more diligent with my testing and treating. So, right now, I’m not overly concerned.

In fact, I just tested my water today:

TA = 40

pH = 7.6

Br = 4.0

I did nothing...when the TA hits 30; I'll add baking soda to get it up to 60. Usually, baking soda is the only chemical I add, after my initial balancing of my fill water, for the life of that fill (with the exception of the bromine floater). So, only adding baking soda about once a month for the 3 - 4 month fill seems fairly safe to me.

Good luck with your situation. If you get it where you want it, it will be nice to hear how you made that happen.

Interesting - I'll keep you posted.

Surely you also shock? I have an ozonator, so I keep my bromine much lower (1-2ppm). I try to shock twice per week with about 2oz of MPS. That temporarily raises the bromine, but is necessary to rid the water of the debris from bacteria that the sanitizer has killed.

[waterbear]

[

Look again my friend. pH up is indeed sodium bicarbonate (otherwise known as Sodium Hydrogen Carbonate = same thing). Anyway, that's what I use.

pH up is sodium CARBONATE aka sal soda, soda ash, or washing soda

Alkalinity up is sodium BICARBONATE aka sodium hydrogen carbonate or baking soda.

Both will cause TA and pH to rise but sodium carbonate will cause much more of a pH rise than sodium carbonate.

Where you put your TA depends a lot on what santizer you are using and whether you use MPS for shocking.

Dichlor, bromine,and MPS are acidic and will cause TA to drop so running a higher TA with these products leads to a more stable pH.

Aeration will cause pH to rise so if your venturis that inject air in your jets are not adjustable (which I find very strange indeed) then you might want to run a much lower TA for increased pH stability. Also, if your primary sanitizer is an unstabilized chlorine (cal hypo, lithium hypochlorite or sodium hypochlorite) then running a much lower TA will lead to a more stable pH.

Also, get your pH to about 7.6. If you drop it lower you will actually cause the pH to rise faster then if you keep it at about 7.6.

[fdegree]

Interesting - I'll keep you posted.

Surely you also shock? I have an ozonator, so I keep my bromine much lower (1-2ppm). I try to shock twice per week with about 2oz of MPS. That temporarily raises the bromine, but is necessary to rid the water of the debris from bacteria that the sanitizer has killed.

Yes, I shock with liquid bleach, about once every 2 -3 weeks (sorry, I forgot to mention this). I realize this is not as frequent as instructed by most, but again, we don't use the spa too frequently.

I also have an ozonator, but my floater is barely cracked open. If I close it any further to get my bromine level down, I will have no bromine reading. In fact, I haven't had to add bromine tabs to the floater in over a month and it is still more than 3/4 full. As mentioned before, I believe this is also due to infrequent usage.

Maybe when we retire (in another 50 years :-)) we'll have time to use it more often.

[wireman]

I don't worry about TA... If my PH is good I could care less what the TA is. This method is the wireman method : ) Listen to waterbear and chemgeek.

[waterboy]

[

Look again my friend. pH up is indeed sodium bicarbonate (otherwise known as Sodium Hydrogen Carbonate = same thing). Anyway, that's what I use.

pH up is sodium CARBONATE aka sal soda, soda ash, or washing soda

Alkalinity up is sodium BICARBONATE aka sodium hydrogen carbonate or baking soda.

Both will cause TA and pH to rise but sodium carbonate will cause much more of a pH rise than sodium carbonate.

Where you put your TA depends a lot on what santizer you are using and whether you use MPS for shocking.

Dichlor, bromine,and MPS are acidic and will cause TA to drop so running a higher TA with these products leads to a more stable pH.

Aeration will cause pH to rise so if your venturis that inject air in your jets are not adjustable (which I find very strange indeed) then you might want to run a much lower TA for increased pH stability. Also, if your primary sanitizer is an unstabilized chlorine (cal hypo, lithium hypochlorite or sodium hypochlorite) then running a much lower TA will lead to a more stable pH.

Also, get your pH to about 7.6. If you drop it lower you will actually cause the pH to rise faster then if you keep it at about 7.6.

I have a low TA of 50 and my PH is 7.0. I have sodium hydrogen Carbonate. I do not want to raise the PH too much so could you clarify the statement from above

Both will cause TA and pH to rise but sodium carbonate will cause much more of a pH rise than sodium carbonate.

Which one of the above sodium carbonates is actually sodium bicarbonate?

[Hillbilly Hot Tub]

I have a low TA of 50 and my PH is 7.0. I have sodium hydrogen Carbonate. I do not want to raise the PH too much so could you clarify the statement from above

Both will cause TA and pH to rise but sodium carbonate will cause much more of a pH rise than sodium carbonate.

Which one of the above sodium carbonates is actually sodium bicarbonate?

Sodium Bi carbonate = Sodium hydrogen carbonate = Alkalinity increaser

Sodium Carbonate = PH increaser

Water bear had a typo....it should be sodium carbonate will cause more of a PH rise than sodium bi-carbonate

Sodium bi carbonate and sodium hydrogen carbonate is the same. Use sodium hydrogen carbonate to raise your levels, since you need to raise both, and this one will not raise the PH as quickly.

[waterboy]

Thanks for your response. I added enough sodium bicarbonate last night to supposedly raise the TA by 25 so I should be up to 75. I will check tonight and if the PH is up to 7.4 to 7.6 I will leave well enough alone for now

[chem geek]

In theory, if you start with a pH of 7.0 and TA of 50 and add 2 ounces weight (about 3 tablespoons or 9-1/2 teaspoons) in 350 gallons of baking soda (Alkalinity Up / Sodium Bicarbonate / Sodium Hydrogen Carbonate), then this will raise the TA to 75 but the pH will only rise to 7.15 so let us know what you find.

If you instead add 1-1/4 ounces weight (about 2 tablespoons or 6-1/2 teaspoons) of Arm & Hammer Washing Soda (pH Up / Sodium Carbonate), then this will raise the TA to 75, but the pH will rise to 8.50

So it gets tricky when you want to raise both pH and TA by specific amounts since a combination is needed. If one is going to use the above chemicals, then adjusting the pH first and then the TA usually gets you pretty close. If you do it the other way around, then the pH adjustment will increase the TA too much. If you add 0.4 ounces weight (about 2 teaspoons) of pH Up first (pH goes to 7.43) and then 1.3 ounces weight (about 2 tablespoons or 6-1/2 teaspoons) of Alkalinity Up, then you end up with the desired pH of 7.5 and TA of 75.

Another alternative is to use a pH adjuster that does not increase TA as much, such as using Borax instead. If we adjusted the TA as noted above with baking soda, then starting at TA 75 and pH 7.15 one can add 1.2 ounces weight (about 2-1/4 tablespoons or 6-1/4 teaspoons) of 20 Mule Team Borax which will raise the pH to 7.5 and only raise the TA to 81.6 (and the TA is raised without carbonates so without contributing to outgassing of carbon dioxide that causes pH to normally rise).

Richard

[Hillbilly Hot Tub]

In theory, if you start with a pH of 7.0 and TA of 50 and add 2 ounces weight (about 3 tablespoons or 9-1/2 teaspoons) in 350 gallons of baking soda (Alkalinity Up / Sodium Bicarbonate / Sodium Hydrogen Carbonate), then this will raise the TA to 75 but the pH will only rise to 7.15 so let us know what you find.

If you instead add 1-1/4 ounces weight (about 2 tablespoons or 6-1/2 teaspoons) of Arm & Hammer Washing Soda (pH Up / Sodium Carbonate), then this will raise the TA to 75, but the pH will rise to 8.50

So it gets tricky when you want to raise both pH and TA by specific amounts since a combination is needed. If one is going to use the above chemicals, then adjusting the pH first and then the TA usually gets you pretty close. If you do it the other way around, then the pH adjustment will increase the TA too much. If you add 0.4 ounces weight (about 2 teaspoons) of pH Up first (pH goes to 7.43) and then 1.3 ounces weight (about 2 tablespoons or 6-1/2 teaspoons) of Alkalinity Up, then you end up with the desired pH of 7.5 and TA of 75.

Another alternative is to use a pH adjuster that does not increase TA as much, such as using Borax instead. If we adjusted the TA as noted above with baking soda, then starting at TA 75 and pH 7.15 one can add 1.2 ounces weight (about 2-1/4 tablespoons or 6-1/4 teaspoons) of 20 Mule Team Borax which will raise the pH to 7.5 and only raise the TA to 81.6 (and the TA is raised without carbonates so without contributing to outgassing of carbon dioxide that causes pH to normally rise).

Richard

Richard,

On my personal exsperience when I use ALK increaser(sodium hydrogen carbonate) my PH rises much more than your predictions. Example. My personal tub....ALK was at 60, PH was at 7.4. Bromine tub, not tablets that are mixed with chlorine, 99.4% 1,3-dibromo-5, 5-dimethythydantoin, the other .6% is unknown. MPS shock, weekly stain and scale control. 480 gallon tub. I used 2 ounces of ALK and my ALK went up to 85 and my PH went up to 8.2. It drives me nuts, this consistantly happens to not just me, by others also and even those using other sanitation systems IE Nature 2 or tradional Bromine tabs. It would be so much easier if the PH did not rise as much, like you state above, when we add ALK increaser, but it seems to and this is why so many have an issue getting the tubs to test out properly. Any ideas why we get differnt results with our ALK addtions?

[Hillbilly Hot Tub]

In theory, if you start with a pH of 7.0 and TA of 50 and add 2 ounces weight (about 3 tablespoons or 9-1/2 teaspoons) in 350 gallons of baking soda (Alkalinity Up / Sodium Bicarbonate / Sodium Hydrogen Carbonate), then this will raise the TA to 75 but the pH will only rise to 7.15 so let us know what you find.

If you instead add 1-1/4 ounces weight (about 2 tablespoons or 6-1/2 teaspoons) of Arm & Hammer Washing Soda (pH Up / Sodium Carbonate), then this will raise the TA to 75, but the pH will rise to 8.50

So it gets tricky when you want to raise both pH and TA by specific amounts since a combination is needed. If one is going to use the above chemicals, then adjusting the pH first and then the TA usually gets you pretty close. If you do it the other way around, then the pH adjustment will increase the TA too much. If you add 0.4 ounces weight (about 2 teaspoons) of pH Up first (pH goes to 7.43) and then 1.3 ounces weight (about 2 tablespoons or 6-1/2 teaspoons) of Alkalinity Up, then you end up with the desired pH of 7.5 and TA of 75.

Another alternative is to use a pH adjuster that does not increase TA as much, such as using Borax instead. If we adjusted the TA as noted above with baking soda, then starting at TA 75 and pH 7.15 one can add 1.2 ounces weight (about 2-1/4 tablespoons or 6-1/4 teaspoons) of 20 Mule Team Borax which will raise the pH to 7.5 and only raise the TA to 81.6 (and the TA is raised without carbonates so without contributing to outgassing of carbon dioxide that causes pH to normally rise).

Richard

Richard,

On my personal exsperience when I use ALK increaser(sodium hydrogen carbonate) my PH rises much more than your predictions. Example. My personal tub....ALK was at 60, PH was at 7.4. Bromine tub, not tablets that are mixed with chlorine, 99.4% 1,3-dibromo-5, 5-dimethythydantoin, the other .6% is unknown. MPS shock, weekly stain and scale control. 480 gallon tub. I used 2 ounces of ALK and my ALK went up to 85 and my PH went up to 8.2. It drives me nuts, this consistantly happens to not just me, by others also and even those using other sanitation systems IE Nature 2 or tradional Bromine tabs. It would be so much easier if the PH did not rise as much, like you state above, when we add ALK increaser, but it seems to and this is why so many have an issue getting the tubs to test out properly. Any ideas why we get differnt results with our ALK addtions?

[Hillbilly Hot Tub]

This is a copy from our class, this class taught us to adjust Alkalinity first, not PH. We were told to raise the ALK as close as we could without bringing the PH to high, and if we got the ALK to 80 and if you still needed to raise the PH use PH increaser to bring that up the rest of the way.

This write up is in another thread somewhere, but I'll put it in again.

Alkalinity

Total alkalinity is the measure of the amount of alkaline buffers (primarily carbonates and bicarbonates) in your water. These alkaline substances buffer the water against sudden changes in pH. Total alkalinity is considered the key to water balance. It is the first parameter you should balance when making routine adjustments to your water.

If you neglect to check the total alkalinity in your pool or spa, you may have trouble balancing the pH. You may also notice that pH fluctuates suddenly despite your best efforts to keep it in the ideal range. If the alkalinity is too low, anything introduced to the water will have an immediate impact on pH. Abrupt shifts in pH can cause scaling or corrosion of metal equipment and fixtures as well as other problems. When the total alkalinity is high, the pH has a tendency to drift upward, causing scale to form.

Maintaining an ideal level of alkalinity will protect your pool or spa and its equipment from the harmful effects of sudden pH fluctuations. Think of the alkalinity as training wheels: it keeps the pH in balance without allowing it to tip too far to either side. Of course the pH can still drift upward or downward, but that change will happen gradually as long as the alkalinity falls within the ideal range. The ideal range of total alkalinity for pools and spas is between 80 and 120 ppm (mg/L).

When the total alkalinity is too low, add sodium bicarbonate. If the total alkalinity is too high, you can lower it by using muriatic acid or sodium bisulfate.

This is a copy of the PH description we had.

pH

We use pH as an index to express how acidic or basic a solution is. (The scientific definition of pH is “the negative logarithm of the hydrogen ion concentration”.) A pH greater than 7.0 is basic, and a pH lower than 7.0 is acidic. In pools and spas, it is important to maintain the water in the slightly basic range of 7.2 to 7.8. The National Spa and Pool Institute (NSPI), the industry association in the United States, has set a standard of 7.2 to 7.6 as the ideal pH.

If pH Is Low:

The water can corrode surfaces, metal equipment or fixtures.

Swimmers and bathers can experience discomfort from burning eyes and itchy skin.

The chlorine may dissipate more quickly.

The water may cause pitting and etching of plaster surfaces.

If pH Is High:

Calcium and metals tend to come out of solution (the opposite of dissolving) at high pH levels, creating the potential for staining and scale formation. The calcium and metals will actually create deposits and discoloration on pool walls and equipment.

Swimmers and bathers can experience discomfort from burning eyes and itchy skin.

High pH can contribute to cloudy water.

[waterboy]

Thanks for your comments chem geek and hillbilly. Here is what I did last night

tub is 1700 litres

I used spa essentials alkalinity up which is 100% Sodium bicarbonate. Instruction for an increase of 25 TA was 67.5 grams for 1500 litres so I added 75 grams.

I will let you know how it turned out

[waterbear]

Water bear had a typo....it should be sodium carbonate will cause more of a PH rise than sodium bi-carbonate

Sodium bi carbonate and sodium hydrogen carbonate is the same. Use sodium hydrogen carbonate to raise your levels, since you need to raise both, and this one will not raise the PH as quickly.

Thanks for catching that one!!! That's what happens when you don't proofread the post!!!

[waterbear]

Onew thing that people are neglecting to look at as far a pH rise is that AERATION and the outgassing of CO2 is what causes the pH to rise in either a tub or pool. Hottubs have a LOT of aeration, what with the venturi jets, bubblers, and blowers so pH will rise fast in a hot tub, particularly if the TA is high and/or the pH is on the low side. To get the best pH stability run the TA around 90-100 ppm for acidic sanitizers (dichlor, bromine tablets, MPS) and around 60-70 for alkaline sanitizers (cal hypo, lithium hypo, sodium hypo.) Limit the venturis and bubblers and blowers to when you are actually using the tub if possible. If you have an ozone system this, unfortunatly, usually will aerate the water and cause CO2 to outgas. Ditto for a bromine generator or a SWG.

Keep you pH on the high end (7.6 for chlorine, when it hits 7.8 drop it back to 7.6 and no lower. 7.8 for bromine, when it hits 8.0 drop it back to 7.8) The lower the pH the faster CO2 will outgas. (Lower pH converts some of the bicarbonate in the water into carbonic acid, essentially CO2 dissovled in water. Think club soda or seltzer, which is just CO2 dissolved in water. If you have more CO2 it will outgas faster with aeration. Think shaking up a bottle of club soda to make it go flat. Now you have decreased the amount of carbon dioxide in the water or, to put it another way, the amount of carbonic acid in the water. Key word here is acid. You have reduced the amount of acid so the pH goes up. (This is very oversimplified and not totally correct but is close enough to what happens so those not versed in chemistry can understand!)

The reason to run the TA as low as possible for the kind of sanitizer is to avoid "overcarbonating" the water. The less carbonation the less carbonic acid (carbon dioxide) that is in the water and the slower the pH will rise.

IF you read this until you undertand what is going on you will really have control of your water with respect to pH and TA! I know I gave some narrow parameters for pH and TA but this is why I say a GOOD testkit (such as the Taylor ones) is going to make your water balancing much easier. This cannot be done with 'guess strips' but with a good testkit it's actually pretty easy. You wll find that you might be adding baking soda more often to keep the TA in range but you will be adding a very small amount at a time.

It really isn't rocket science but it is some basic chemistry.

[wireman]

Screw TA I say and balance PH! Your mileage may vary : )