Another PH question

[Nitro]

I have been been chasing my tail.  Start to get  ph in than ak low.  Add ak increaser than ph high.  Done this 3 times now.  When I get the ph in the ak is pretty low.  I have my ak at around 100 now and ph is high.  Will just let set for a week and see where it ends up.  Is it worst to have high ph or low ak?

I wouldn't bother letting it sit for a week, because it will end up right where you left it, with high TA and pH.

First thing you need to do is, STOP adding Alk Increaser (Baking Soda). There is no reason to use it, unless your TA is very low < 50, and/or your pH won't rise above 7.2 from continued aeration (i.e. running your Jets/Air). In your case this should not happen, unless you add too much acid. Also, there is no reason to use Soda Ash. You should only raise pH by aeration.

If you want to balance your water, you need to lower your TA to 60-80 range. This will stop your pH from creeping up too high (> 8.0) via aeration. I suggest lowering it to 80, then adjust it on an ongoing basis. Your Calcium is fine at 190 ppm and doesn't need adjusting.

To lower TA follow these directions exactly.

1. Add enough acid to lower your pH to 7.0.
2. Run all your jets and air features for 30 mins.
3. Check TA and pH.
4. If TA > Target and pH > 7.8, goto step 1.
5. Run all your jets and air features for 60 mins.
6. Check TA and pH.
7. If TA > Target and pH > 7.8, goto step 1.
8. If TA > Target and pH < 8.0, stop. Your TA is fine for now.

Now, continue to use your tub as normal. However, right after every soak, check TA and pH. If pH > 8.0, lower your TA by 5 ppm using the above method.

If you continue to do this your TA will be fine tuned to a level that won't allow pH to rise via aeration. Again, this should be in the 60-80 range, but it could be 50 ppm. Don't go below 50 ppm TA, you shouldn't need to anyway.

If and ONLY if your pH is < 7.4 and will not rise from continued aeration (i.e. over 2 hours), you can raise TA by 5 ppm using Baking Soda. (1 tbs) However, this should never happen if you did the above procedure correctly.

Lastly, in order to calculate how much acid or base to use, goto http://www.thepoolcalculator.com/ and plug in your values. It will calculate everything you need to know.

Good luck.

[brian_tr]

Thanks for replies.  I will do as suggested.

[gadfly]

.... First thing you need to do is, STOP adding Alk Increaser (Baking Soda). There is no reason to use it, unless your TA is very low < 50, and/or your pH won't rise above 7.2 from continued aeration (i.e. running your Jets/Air). In your case this should not happen, unless you add too much acid. Also, there is no reason to use Soda Ash.

You should only raise pH by aeration.....To lower TA follow these directions exactly.

1. Add enough acid to lower your pH to 7.0.
2. Run all your jets and air features for 30 mins.
3. Check TA and pH...

Nitro, I agree with most of your post, but I find that trying to test pH/TA after adding chems any sooner than a couple of hours, may give false reading.  It sometimes takes longer than that, for the base/acid reaction to finish.  I believe that some of the "chasing the tail" occurs as a result of testing too soon.  I personally wait until the next day to test, and add more acid/base if necessary.

I also question the reliance on aeration to raise pH.  Tubs without air systems, do not get as much aeration, and in my experience once the water is balanced, aeration has little impact.  Carbonates are often needed to raise pH to manage MPS and bromine.  Even dichlor users need to grab the baking soda or ash, as the water ages.

I am always leary of recommendations that tell people that they have to do "these directions exactly", and "this will never happpen, if you did the above procedure correctly".  Notice the wide differences between your approach and Ndbunka.  I used to visit another spa forum that had a couple of regulars who always thought they had the only approach, and fail to realize that we don't always know all the variables of a situation.  Don't fall into that trap.

[Nitro]

Nitro, I agree with most of your post, but I find that trying to test pH/TA after adding chems any sooner than a couple of hours, may give false reading.  It sometimes takes longer than that, for the base/acid reaction to finish.  I believe that some of the "chasing the tail" occurs as a result of testing too soon.  I personally wait until the next day to test, and add more acid/base if necessary.

I lowered the TA in tub from 400 ppm to 80 ppm in just a few hours. There is no need to wait a day between checking, unless you don't have the time. Acid will lower TA by an exact amount that can be calculated. It takes ~8 oz Dry Acid to lower TA by 100 ppm in a 350 Gal Tub. The only reason not to add all the acid at once is becuase the pH will drop too much (<7.0). That's why you aerate to keep raising it.

I also question the reliance on aeration to raise pH.  Tubs without air systems, do not get as much aeration, and in my experience once the water is balanced, aeration has little impact.  Carbonates are often needed to raise pH to manage MPS and bromine.  Even dichlor users need to grab the baking soda or ash, as the water ages.

Older tubs with less air just take longer to raise pH via aeration, but ALWAYS do. As a matter of fact, you can raise pH in a pool with very little aeration compared to hot tubs. The higher the TA, the more effect aeration will have on raising pH. There is no reason to use Soda Ash to raise pH. If pH is too low, and you can't raise it via aeration, your TA is too low and needs to be raised, with Baking Soda.

Your quote of "in my experience once the water is balanced, aeration has little impact." is exactly what we are trying to achieve. This only happens with a lower TA. If TA is higher, aeration has more of an impact on pH. I agree Dichlor users need to keep TA a little higher and may need to add Baking Soda, once in a while. But if your water is well balanced it will not be very often. If you notice, my procedure does say, "If and ONLY if your pH is < 7.4 and will not rise from continued aeration (i.e. over 2 hours), you can raise TA by 5 ppm using Baking Soda."

I am always leary of recommendations that tell people that they have to do "these directions exactly", and "this will never happpen, if you did the above procedure correctly".  Notice the wide differences between your approach and Ndbunka.  I used to visit another spa forum that had a couple of regulars who always thought they had the only approach, and fail to realize that we don't always know all the variables of a situation.  Don't fall into that trap.

I have used this appraoch personally on my own spa and on friends spas (some older). I have also seen it work on many online user's spas. This is the best approch to lowering TA without lowering pH also. And, lowering TA is the best way to keep pH from rising via aeration, which happens in most spas. I'd be willing to place a bet that it will work for Brian too.

I will cede your point that all spas act different, and using the words "never" and "exactly" are a little bold. However, there has been alot of misinformation in this thread. I felt the need to post with confidence, or it would have just gotten lost in the shuffle. Brian doesn't need to be confused. He needs a method that will balance his water (i.e. lower his TA), and this will do it.

[Nitro]

Thanks for replies.  I will do as suggested.

Let us know how it works out, and if you have any questions.

Also, what kind of sanitizer are you using?

[gadfly]

Nitro, I find your confidence interesting, with you having admitted that your experience is limited to your tub, and some friends, and what you have seen on-line.  There are members on this and other boards, with experience with hundreds, some thousands of customers... who might have valid you should consider points.  My own experiences both on-line, and real world chemical applications, is that the makeup of the source water, has a major impact on the strategy for water management.  For example, water from deep wells, vs rivers, vs lake sources can all create unexpected challenges.  Add in metals, organics, and municipal water treatment in issues... and in my opinion, things are not always as clear-cut as "follow my procedure".  

One of the reasons I had dropped off these boards for a while, was because I tired of mis-information, and others who thought they had all the answers.  In this thread, I only saw one post that trying to help was on the wrong track and which admitted that "chem experts" were needed... and one that was "mis-information" who was sure the rest of us were wrong.  Most everyone was clarifying similar suggestions.

The good news is that brian got good info, if it took too many posts to weed through.   Given your question twice of what sanitizer brian uses, has to got me curious what type you use?  I'll go first... I have used dichlor, bleach, and bromine, with/without supplemental sources of metals and ozone at different times in the past.  I now use dichlor/bleach and N2 when the seasons the tub gets alot of use, and bromine when it is not.

[brian_tr]

Added ph down earlier today and just checked water and ph is 7.5 and alk is 120.  Hardness is 190.  I have had tub for 7yrs and dont remember this much trouble.  I used to add about 3 cups muraitic acid all at once and then check it in about a week and it was right on.  I have since learned it is not a good idea to do all at once so this time I spaced it out.  I use dichlor for sanitizer.  Thanks for all the help.

[Nitro]

Nitro, I find your confidence interesting, with you having admitted that your experience is limited to your tub, and some friends, and what you have seen on-line.  There are members on this and other boards, with experience with hundreds, some thousands of customers... who might have valid you should consider points.  My own experiences both on-line, and real world chemical applications, is that the makeup of the source water, has a major impact on the strategy for water management.  For example, water from deep wells, vs rivers, vs lake sources can all create unexpected challenges.  Add in metals, organics, and municipal water treatment in issues... and in my opinion, things are not always as clear-cut as "follow my procedure".

My confidence not only comes from my own experience, it comes from others who do deal with hundreds of tubs. This procedure is not mine. It has been put together by hundreds, if not thousands of spa users. If you don't think it will work, let us know your approach. I already know this method works, and if Brian uses it he will know too. Spa Water Maintenance is not rocket science, unless you make it.

But I agree, Hell (I mean Well) water is much worse to deal with. My friend (the one with 400 ppm TA) has very bad well water. In that case I filled the tub right from his water softener, and used a pre-filter. Since the water softener removed the calcium, we just added some. No big deal. The hard part was getting his TA down, which took ~30 oz Dry Acid. I added it in only four hours, without the pH ever dropping below 7.0, by using this method.

One of the reasons I had dropped off these boards for a while, was because I tired of mis-information, and others who thought they had all the answers.  In this thread, I only saw one post that trying to help was on the wrong track and which admitted that "chem experts" were needed... and one that was "mis-information" who was sure the rest of us were wrong.  Most everyone was clarifying similar suggestions.

I would not drop off boards because of mis-information. That's the reason I'm here.

The good news is that brian got good info, if it took too many posts to weed through.   Given your question twice of what sanitizer brian uses, has to got me curious what type you use?  I'll go first... I have used dichlor, bleach, and bromine, with/without supplemental sources of metals and ozone at different times in the past.  I now use dichlor/bleach and N2 when the seasons the tub gets alot of use, and bromine when it is not.

I use the Dichlor/Bleach method with 30 ppm CYA. I learned it from the creator himself. I also have 50 ppm Borates in my tub. My CH is at 200, TA is 60 and my pH has been rock solid at 7.8 for the last month (last water change). I have yet to add acid after the initial dose. Sometimes I'll use MPS during high bather loads to help oxidize waste, but I haven't needed to on this water change yet. Bleach is the only thing I add to my tub on a regular basis.

[Nitro]

Added ph down earlier today and just checked water and ph is 7.5 and alk is 120.  Hardness is 190.  I have had tub for 7yrs and dont remember this much trouble.  I used to add about 3 cups muraitic acid all at once and then check it in about a week and it was right on.  I have since learned it is not a good idea to do all at once so this time I spaced it out.  I use dichlor for sanitizer.  Thanks for all the help.

You're going to need ~5.5 oz Dry Acid in a 400 Gal tub to drop your TA by 40 ppm, which will put you at 80 ppm. That's where you need to be at. How many Gallons is your tub?

So, add one ounce Dry Acid, then aerate for 15-30 min.
Check your pH/TA.
If your pH is >7.5, and another oz and continue to aerate.
Do this until your TA is ~80 ppm, which should be 4-5 times depending on your tub size.
Then aerate until your pH is ~7.6 and you're go to go for now.

Keep track of your pH, and adjust TA as needed. No big deal!

[gadfly]

My confidence not only comes from my own experience, it comes from others who do deal with hundreds of tubs....

I use the Dichlor/Bleach method with 30 ppm CYA. I learned it from the creator himself.... Bleach is the only thing I add to my tub on a regular basis.

I figured.  Nothing like a true believer, with most of their experience off the internet, would be so sure.

[Nitro]

I figured.  Nothing like a true believer, with most of their experience off the internet, would be so sure.

Funny, because the method you're using (Dichlor/Bleach) came from the Internet.

Again, if you have a better method on lowering TA, let's hear it.

[gadfly]

Funny, because the method you're using (Dichlor/Bleach) came from the Internet.

I don't think so, my first pool/spa dealer was using bleach, many years ago.  He predates the Internet, and I would take his advice over any one who claims to have invented it.  There is a fine line between confidence and cocky.  You are on the wrong side of the line.  For the record, I think that dichlor and bromine are fine choices for spas, and that hot-tub itch is found more on the internet, than in real tubs.

Pretty much everyone in this thread but two, had the same aproach on helping brian.  Some of us have enough real experience to know that cookbook directions, are less helpful than helping one identify the tools needed, and allow them to make it work in their situation.  

Have a good weekend.  

[Nitro]

I don't think so, my first pool/spa dealer was using bleach, many years ago.  He predates the Internet, and I would take his advice over any one who claims to have invented it.

I'm glad your dealer is using bleach. I think more dealers should teach their customers how to use it, if it weren't for those pesky Warranties. What CYA level does he recommend?

For the record, I have a little experience with Hot Tub itch, and it IS found in real tubs. A friend of mine was trying to follow the advice of his dealer using Bromine, and his wife came down with a rash. I'm not saying there is a problem with Bromine, if used correctly. However, there is a problem with a lot of dealers (not all) who push tubs out the door, and don't spend the time to teach their customers about proper Water Maintenance.

Pretty much everyone in this thread but two, had the same aproach on helping brian.  Some of us have enough real experience to know that cookbook directions, are less helpful than helping one identify the tools needed, and allow them to make it work in their situation.

This "cookbook" procedure works, period. Unless you can come up with a fault with it, i'd suggest you stop criticizing it.

I'm not here to convince you of anything. I'm only here to help Brian, and that's what I intend to do.

[chem geek]

I wasn't going to register here and don't intend to post here regularly, but I do want to comment on this thread since it's getting a bit out of hand.  Everyone please take a deep breath and try and stay away from getting personal.

The essence of this thread, brian's issue, is that his tub was registering very high pH.  His water has high TA and he has been going around in circles with the often prescribed method of "just add acid to lower the TA", but then that drops both pH and TA so the TA may get too low and one adds Alkalinity Increaser and the TA gets to some target.  But then the pH rises again over time so one adds acid to lower it, TA gets too low, more Alk increaser is added, etc.  A vicious cycle.

All that Nitro, tony, nodrewbunkageek and some others were saying was that Total Alkalinity (TA) is not only there to be a pH buffer, that is to stabilize pH, but it is also a SOURCE of rising pH by itself.  Higher TA makes the pH rise more rapidly unless there are other sources of acidity regularly added to the water.  The solution is simply to have a lower TA target and not to try and "set" the TA higher when one is experiencing regular pH rise.

The chemical reason for the above is that pools and spas are intentionally over-carbonated in order to provide a pH buffer and, for plaster pools, to saturate the water with calcium carbonate to prevent dissolving of plaster.  However, the amount of TA at a pH of 7.5 that is equal to the "natural" (equilibrium) amount that would exist with the normal amount of carbon dioxide in the air is only 10 ppm (with no CYA in the water as that also partially registers as TA in the test).  When the TA is higher than that, then carbon dioxide will outgas from the water and this occurs more rapidly when the pH is lower, when the TA is higher, and when there is more aeration (air/water mixing).  The rate of this outgassing is roughly proportional to the square of the carbonate alkalinity or adjusted TA (adjusted down to remove the CYA component).  So a higher TA may buffer the water more against pH changes, BUT the rate of outgassing outstrips this effect so the net result is a rise in pH over time and, for technical reasons I won't get into here, no change in TA.  In practice, water with a TA of 50 or 60 ppm is usually very stable in pH because the rate of outgassing is relatively slow even though it is technically out of equilibrium.

If one is using chemicals that have a net acidity effect, then one wants a higher TA level to balance the tendency of the pH to drop from this acidity.  Dichlor may be relatively pH neutral upon addition, but the usage of chlorine is an acidic process so the net effect of adding Dichlor and having chlorine used up is net acidic.  Non-chlorine shock (monopersulfate, MPS) is acidic upon addition.  Trichlor is very acidic because it's acidic upon addition and then more acidic as chlorine gets used up so is not recommended for spas -- but in pools, this is why the TA is usually 120-140 ppm or more when Trichlor is used.  Hypochlorite sources of chlorine including chlorinating liquid, bleach, lithium hypochlorite and Cal-Hypo have the pH rise upon addition but then drop back down as the chlorine gets used up -- they are close to pH neutral when accounting for both addition and consumption.  Any net pH rise that is seen is mostly due to outgassing of carbon dioxide; that is, to a TA level that is too high.

As for how long it takes for chemicals to react and for re-testing, the theory says that the reactions are relatively fast -- even the "slower" ones relating to dissolved carbon dioxide and carbonic acid.  The really slow reaction is the exchange of dissolved carbon dioxide from the water to the air.  Essentially, if one adds acid or base to the water over a return flow and waits after circulating even 10 minutes, the pH reading should be OK.  Nevertheless, I've heard about this problem before so I experimented in my 16,000 gallon pool and found that both with chlorine and with acid the changes to measurements of FC and pH stabilized within 30 minutes and that most of the change was in the first 10 minutes.  I have very good circulation in the pool and verified that by using a "blue dye" test to visually see the mixing.  If one waits too long after a chemical addition, then the outgassing of carbon dioxide may result in the pH rising.  That's not a problem, of course, but would look as if the acid addition didn't do as much as predicted (assuming one can predict -- doing so is difficult since the effect on pH from acid or base depends on the TA level).

As for the difference between baking soda (sodium bicarbonate aka sodium hydrogen carbonate; Alkalinity Up/Increaser) and soda ash (sodium carbonate; pH Up/Increaser), there is often confusion about this.  The "bi" in bicarbonate does NOT mean two carboantes.  In chemistry, the "bi" is often associated with hydrogen where sodium bicarbonate is NaHCO₃ whereas sodium carbonate is Na₂CO₃.  Both of these increase the amount of carbonate in the water by the same amount on a molar basis.  The difference is that the sodium carbonate raises the pH in addition to the TA.  In fact, adding sodium carbonate is chemically identical to adding a combination of baking soda (sodium bicarbonate) and lye (aka caustic soda; sodium hydroxide).  Adding Baking Soda does not raise pH by very much and should never be used to adjust pH.

(to be continued...)

[chem geek]

One more thing regarding pH and TA.  When adding an acid or a base to the water, both pH and TA will move together.  With pH Up / Soda Ash / Sodium Carbonate, the TA will move up twice as much for the same pH move as compared to using a pure base such as lye or a mostly pure base (at spa pH) such as 20 Mule Team Borax.

As for hot tub itch being reported on the Internet, that is certainly true and I've kept track of that on one forum here, but many incidents are not confirmed by doctors and could just be heat and pressure (from jets) rashes and there aren't enough to know for certain what is going on.  I just wanted to see if it was related to Dichlor-only use -- clearly letting the FC get to zero was a problem in some cases, but when chlorine was maintained the question was whether the buildup of CYA made chlorine so ineffective that hot tub itch bacteria could grow (possibly in biofilms).  As I said, this isn't definitive, but there's nothing else to go on.

As for the Dichlor-then-bleach method, Nitro is attributing that to me because at the time this was something I came up with based on the chemistry of chlorine and Cyanuric Acid (CYA).  I don't claim to be the first one to think of it (though I had not seen it described before as such), especially since it's just based on common sense understanding of the chemistry.  It's really just an extension of principles described for pools at The PoolForum and at Trouble Free Pool.  Using bleach alone would generally be too harsh on a hot tub and is probably why most hot tub manufacturers are against it.  However, I don't think they understand how using Dichlor first for about a week to get to at least 20 ppm CYA makes subsequent chlorine addition using bleach orders-of-magnitude less harsh while making the rate of disinfection and oxidation more consistent over time.  I'm glad your dealer figured that out years ago.

The science behind this has been known since at least 1974 and is described in the paper in this link where I recently got permission to reprint/distribute/post the paper that hitherto was only available in some libraries and a few copies that could be purchased.  The industry knows of this paper as is evident by its reference in this EPA PDF file on page 12/13 (PDF page 18/19).

When rereading the posts in this thread, I don't think there was much disagreement; it sounds more like a style issue.  Though one can be certain of basic chemistry, one can never be sure what will happen in a more complex system.  I prefer to assume the chemistry is valid, then see what happens, then adjust the model if theory does not match reality.  So far, this has worked reasonably well.  The one serious exception was when Dichlor-then-bleach was initially used by some (including TinyBubbles) where the pH rise was way too extreme, possibly due to an ozonator in the spa.  That was also before the TA was dropped as aggressively and before we used an additional pH buffer of Borates and higher CH to balance the low TA.  I was royally chewed out by a spa professional for that.

Richard