Bleach In Hot Tubs

[DarinC 0]

Hello, I've decided to try the bleach method to control CYA levels, this seems to be the most recently active thread regarding the topic.  The only bleach available in my local store is the "Concentrated Formula", which appears to be 7.5% bleach as opposed to 6%.  It did mention on the label something to the effect of "makes clothes last longer", which concerned me a bit, since I don't know if that suggests some added ingredient that I wouldn't want in a tub, but I decided to try it.  I am now experiencing a lot of foam.  It goes away with the air off, but it's pretty significant with the air on.  Is this an expected result with all bleach, or would this go away if I found the non-concentrated formula?

Thanks!

[RDspaguy 742]

Most store bought bleach these days has additives. Get pool chlorine.

[DarinC 0]

Thanks, that's what I ended up doing.  Turns out it's cheaper than household bleach anyway, and a little more convenient since it's more concentrated.

[mscdman 11]

On 10/28/2020 at 8:45 AM, DarinC said:

Hello, I've decided to try the bleach method to control CYA levels, this seems to be the most recently active thread regarding the topic.  The only bleach available in my local store is the "Concentrated Formula", which appears to be 7.5% bleach as opposed to 6%.  It did mention on the label something to the effect of "makes clothes last longer", which concerned me a bit, since I don't know if that suggests some added ingredient that I wouldn't want in a tub, but I decided to try it.  I am now experiencing a lot of foam.  It goes away with the air off, but it's pretty significant with the air on.  Is this an expected result with all bleach, or would this go away if I found the non-concentrated formula?

Thanks!

I’ve been using the 7.5% bleach and not experienced any foam in my bromine spa thus far.   Use the bleach to oxidize the bromide. 

[mscdman 11]

On 10/28/2020 at 8:51 AM, RDspaguy said:

Most store bought bleach these days has additives. Get pool chlorine.

What is the chemical name of pool chlorone?

[mscdman 11]

On 10/28/2020 at 8:51 AM, RDspaguy said:

Most store bought bleach these days has additives. Get pool chlorine.

I’m curious about this.   The “additives” in regular bleach are unknown sure but even pool chlorine seems to have them too.  Here’s a photo. “Other ingredients” just like the bleach...

plus this stuff is 8x more expensive than ordinary bleach from what I can tell   I’d love to be proven wrong though and if there’s a product that is just sodium hypochlorite without extras let me know where it can be found  as I’d look into it  

 

[mscdman 11]

I stand corrected.  Walmart has pool chlorine 10% sodium hypochlorite for only 3.74.$.  With the higher % concentration it IS cheaper than plain bleach.  Not sure about additives.  Either way no reason for me not to use this over the bleach

[RDspaguy 742]

Pool chlorine is not going to have anything that might affect your spa. Laundry bleach may have a variety of different stuff in there, sometimes listed alongside hypochlorite sometimes not. I bought some cheap beach, not splashless or anything, just sodium hypochlorite listed, but it looked like I was doing dishes in my spa when I used it. Now I buy pool stuff only.

[Apollothesun 2]

Any preference in brand for pool chlorine?

[waterbear 147]

Most house brand laundry bleach does not contain additives as long as you buy the unscented, unthickened type and make sure it's bleach and not a bleach cleaner with detergents.. Janitorial Clorox does not contain additives, Clorox chlorine laundry bleach (the unscented, unthickened kind) has an additive to help prevent dirt from settling back on clothes. However, this additive is also the active ingredient in most pool and spa water clarifiers and has the effect of causing the particles that are clouding the water (and probably passing through the filter) to clump together into larger particles that can be filtered out. Therefore, while there IS an additive it is one that is possibly beneficial and certainly nothing that will have any adverse effects in the low concentration present in the bleach.

[mscdman 11]

I’m seeing that each time I add bleach my PH is rising a little higher than I want when it was in range before my soak and adding the bleach.  Is it normal to have to add a little PH down with each addition of bleach/pool chlorine?

I only add 1 tsp to bring it back I range but just wondering if it’s normal to have to add everytime you add the bleach/pool chlorine

[waterbear 147]

What is the pH before you add the bleach and what does it rise to after adding the bleach?  Also, what is your TA? If you are trying to run your pH too low you will have pH stability problems.  Same If your TA is too high. Adding pH down with each bleach addition is not a good idea and not necessary if your numbers are in the correct range. Also, saying that your numbers were "in range" or "a little higher than I want" tell us nothing about the conditions in your tub. We need actual numbers and your testing method to help determine what's going on 

Bleach is net pH neutral. It is alkaline when added but the reaction when it is consumed is net acidic so its effect on pH is negligible. 

[mscdman 11]

15 minutes ago, waterbear said:

What is the pH before you add the bleach and what does it rise to after adding the bleach?  Also, what is your TA? If you are trying to run your pH too low you will have pH stability problems.  Same If your TA is too high. Adding pH down with each bleach addition is not a good idea and not necessary if your numbers are in the correct range. Also, saying that your numbers were "in range" or "a little higher than I want" tell us nothing about the conditions in your tub. We need actual numbers and your testing method to help determine what's going on 

Bleach is net pH neutral. It is alkaline when added but the reaction when it is consumed is net acidic so its effect on pH is negligible. 

According to the Taylor k-2005 kit PH using reagent 004 before soak is 7.5. After soak and adding bleach it gets up to about 8.1ish after a retest after 20 mins.  
 

TA is about 140 according to Taylor kit. 
 

given these factors what do you think could be causing the rise in PH if not for the bleach?

 

im using the bleach to reactive the bromine   Perhaps not enough free bromine?

I’d like to keep it in the proper PH range which I’m to understand is 7.5 to 7.8

is it possible I’m not waiting long enough after adding the bleach to reactivate the bromine to retest (I’m only waiting 20 mins) 

 

 

[waterbear 147]

When you add the bleach what is your sanitizer reading before adding the bleach and what is it immediately after? How much bleach are you adding, what is the strength, and what is the volume of your tub? Please post a full set of test results including sanitizer before adding bleach, sanitizer after adding bleach (wait just long enough for it to mix, about 5 minutes with jets going should be more than enough time), also test pH before and after. Don't add any pH down and test TA before adding the bleach. Also test CH before adding the bleach (I am trying to avoid interference from high sanitizer in case you are adding too much bleach. Be sure to read the level on the bromine side of your comparator and also, look out for the red color 'flashing' when you add the DPD reagent (Color flashed red and then turns either clear or lighter pink as you add the drops). This often means a high sanitizer level, the DPD is bleaching out, and you need to dilute your sample to get an accurate reading, (which is why I prefer the FAS-DPD test in the K-2006 over the DPD test in the K-2005. You can buy a stand alone FAS-DPD kit from Taylor that will convert your kit to a K-2006 since all the other tests in the kit are the same.

1 hour ago, mscdman said:

is it possible I’m not waiting long enough after adding the bleach to reactivate the bromine to retest (I’m only waiting 20 mins) 

IF you have bromide ions in the water then the reaction is almost instantaneous. If not you have chlorine instead of bromine but the point is moot. You have active sanitizer in the water. My question now is what is the sanitizer level after adding the bleach? Are you shocking or just trying to bring the level up to a 4 to 6 ppm range?  High sanitizer levels can cause the pH test to read high when it's not.

1 hour ago, mscdman said:

TA is about 140 according to Taylor kit. 

WAY TOO HIGH! Should be 50-70 ppm if you are oxidizing bromide with bleach for a bromine tub. This could be part of your problem but I suspect a few things are happening.

 

1 hour ago, mscdman said:

According to the Taylor k-2005 kit PH using reagent 004 before soak is 7.5

Just to be clear, this means you are getting a color that is in between the 7.4 and the 7.6 color block, correct? It's really a bit low. Bromine is active up to a pH of about 8.0 and the pH will be more stable if you don't place it to low. Here are some  often overlooked truths about pH and TA:

THE MAIN CAUSE OF pH RISE IN A POOL OR SPA IS OUTGASSING OF CO2.

THE HIGHER THE TA (CARBONATION IN THE WATER), THE FASTER CO2 WILL OUTGAS AND THE FASTER THE pH WILL RISE.

THE HIGHER THE AERATION OF THE WATER (OZONE SYSTEMS, SALT WATER SANITIZER SYSTEMS, AIR INJECTORS,  AERATION FROM YOUR JETS, 24 HOUR CIRCULATION ON HIGH SPEED, ETC.) THE FASTER CO2 WILL OUTGAS AND THE FASTER THE pH WILL RISE.

THE LOWER YOU PLACE THE pH THE FASTER IT WILL RISE (YOU ARE CONVERTING MORE BICARBONATE IONS, WHICH IS WHAT WE MEASURE AS TA,  INTO CARBONIC ACID, ESSENTIALLY CO2 DISSOLVED IN THE WATER.

Therefore, lower your TA and run your pH a bit higher, perhaps 7.8.

 

1 hour ago, mscdman said:

I’d like to keep it in the proper PH range which I’m to understand is 7.5 to 7.8

Not sure where you got the idea that the 'proper pH range is 7.5 to 7.8 for bromine but it's wrong. If it came from the Taylor booklet my advice is to only use it for the acid demand test tables and ignore the rest. You can also ignore the watergram. Not applicable to an acrylic or fiberglass tub. If your tub is plaster then it does have some use.

Post the results I asked for and we can take it from there to see what's going on.

 

 

 

[mscdman 11]

8 hours ago, waterbear said:

When you add the bleach what is your sanitizer reading before adding the bleach and what is it immediately after? How much bleach are you adding, what is the strength, and what is the volume of your tub? Please post a full set of test results including sanitizer before adding bleach, sanitizer after adding bleach (wait just long enough for it to mix, about 5 minutes with jets going should be more than enough time), also test pH before and after. Don't add any pH down and test TA before adding the bleach. Also test CH before adding the bleach (I am trying to avoid interference from high sanitizer in case you are adding too much bleach. Be sure to read the level on the bromine side of your comparator and also, look out for the red color 'flashing' when you add the DPD reagent (Color flashed red and then turns either clear or lighter pink as you add the drops). This often means a high sanitizer level, the DPD is bleaching out, and you need to dilute your sample to get an accurate reading, (which is why I prefer the FAS-DPD test in the K-2006 over the DPD test in the K-2005. You can buy a stand alone FAS-DPD kit from Taylor that will convert your kit to a K-2006 since all the other tests in the kit are the same.

IF you have bromide ions in the water then the reaction is almost instantaneous. If not you have chlorine instead of bromine but the point is moot. You have active sanitizer in the water. My question now is what is the sanitizer level after adding the bleach? Are you shocking or just trying to bring the level up to a 4 to 6 ppm range?  High sanitizer levels can cause the pH test to read high when it's not.

WAY TOO HIGH! Should be 50-70 ppm if you are oxidizing bromide with bleach for a bromine tub. This could be part of your problem but I suspect a few things are happening.

 

Just to be clear, this means you are getting a color that is in between the 7.4 and the 7.6 color block, correct? It's really a bit low. Bromine is active up to a pH of about 8.0 and the pH will be more stable if you don't place it to low. Here are some  often overlooked truths about pH and TA:

THE MAIN CAUSE OF pH RISE IN A POOL OR SPA IS OUTGASSING OF CO2.

THE HIGHER THE TA (CARBONATION IN THE WATER), THE FASTER CO2 WILL OUTGAS AND THE FASTER THE pH WILL RISE.

THE HIGHER THE AERATION OF THE WATER (OZONE SYSTEMS, SALT WATER SANITIZER SYSTEMS, AIR INJECTORS,  AERATION FROM YOUR JETS, 24 HOUR CIRCULATION ON HIGH SPEED, ETC.) THE FASTER CO2 WILL OUTGAS AND THE FASTER THE pH WILL RISE.

THE LOWER YOU PLACE THE pH THE FASTER IT WILL RISE (YOU ARE CONVERTING MORE BICARBONATE IONS, WHICH IS WHAT WE MEASURE AS TA,  INTO CARBONIC ACID, ESSENTIALLY CO2 DISSOLVED IN THE WATER.

Therefore, lower your TA and run your pH a bit higher, perhaps 7.8.

 

Not sure where you got the idea that the 'proper pH range is 7.5 to 7.8 for bromine but it's wrong. If it came from the Taylor booklet my advice is to only use it for the acid demand test tables and ignore the rest. You can also ignore the watergram. Not applicable to an acrylic or fiberglass tub. If your tub is plaster then it does have some use.

Post the results I asked for and we can take it from there to see what's going on.

 

 

 

Thanks for all your help. I’ll check it all out tonight and post results thank you.    I think though that you may have solved the issue with something you said above:

per pool math calculator, I’m bringing the bromine level up from 4 ppm pre soak (and about 0 after soak) to 10-12ppm  after soak by adding 10% concentration sodium hypochlorite  1.25oz   In a 215 gallon fiberglass (?) acrylic (?) marquis tub.    I do this because I use the tub every other day and raising it to 10-12ppm with decay brings me down to 1-4ppm when I try and soak the day after the off day.   It also prevents me from having to add anything on the off day.  
 

I will do all the pre and post tests you mention above though and repost the results but my initiaL thought now is that the PH is reading artificially high because the bromine level after adding bleach to bring it over 10ppm after I use the tub and then testing is making the PH read higher than it really is.     

While I’m waiting to test and provide the data, can you answer the following:

 

1) what is the proper acceptable or target PH range for a bromine tub if not 7.5 to 7.8?  You say bromine is active up to 8.   Yes, when I mentioned my Ph is 7.5 pre soak it is a color between the two blocks on the test kit and that is how I determined it.  

2) how does one lower TA while not lowering PH too low, should I need to adjust it?   I’m asking because if my 140 ppm TA is way to high what steps are taken to lower the TA and then raise the PH back to 7.8?

 

 

 

[waterbear 147]

42 minutes ago, mscdman said:

what is the proper acceptable or target PH range for a bromine tub if not 7.5 to 7.8?

Whatever number is giving you pH stability. pH WILL rise. It's a given in a hot tub. The goal is to minimize the rise for the longest period of time. Running a higher pH and a lower TA is how this is achieved. Also adding borate to 50 ppm is helpful since it introduces a secondary boric acid/borate pH buffer that works with the carbonic acid/bicarbonate buffer (TA) to help maintain the pH around 7.7 for a longer time period than without the borate but first the TA needs to be much lower than yours currently is. To lower you can't lower TA without lowering pH. The trick is to bring the pH back up without raising TA. This cannot be done by adding a chemical. It's done by aerating to cause CO2 to outgas. It is a process that has to be repeated until the TA is where you want it but once it's done it's pretty stable until you refill or add either TA increaser (which is nothing more than ordinary baking soda-sodium bicarbonate, sodium hydrogen carbonate, btw) or pH increaser (ordinary washing soda-sodium carbonate).

Read this to learn how to lower TA:

https://www.poolspaforum.com/forum/index.php?/topic/28846-lowering-total-alkalinity-howto/

 

[sophiemurray 0]

As far as I know, you don't have to use bleach. It can be damaging for the bath. I have a hot tub at home, and I don't use bleach, never! Bleach can deteriorate filter media and permanently damage your hot tub cover. I would recommend using white vinegar and water in a bucket or spray bottle. That is the way I clean my hot tub. I have it for two years already, it doesn't need much maintenance. And having a saltwater hot tub has a lot of benefits for me, I've ordered it from this site https://poolcareschool.com/salt-water-hot-tub/. When I lay there, my skin becomes softener and saltwater soothes it. It's very important for me because I'm 56 and my skin is no longer elastic as it was.

[mscdman 11]

1 hour ago, waterbear said:

Whatever number is giving you pH stability. pH WILL rise. It's a given in a hot tub. The goal is to minimize the rise for the longest period of time. Running a higher pH and a lower TA is how this is achieved. Also adding borate to 50 ppm is helpful since it introduces a secondary boric acid/borate pH buffer that works with the carbonic acid/bicarbonate buffer (TA) to help maintain the pH around 7.7 for a longer time period than without the borate but first the TA needs to be much lower than yours currently is. To lower you can't lower TA without lowering pH. The trick is to bring the pH back up without raising TA. This cannot be done by adding a chemical. It's done by aerating to cause CO2 to outgas. It is a process that has to be repeated until the TA is where you want it but once it's done it's pretty stable until you refill or add either TA increaser (which is nothing more than ordinary baking soda-sodium bicarbonate, sodium hydrogen carbonate, btw) or pH increaser (ordinary washing soda-sodium carbonate).

Read this to learn how to lower TA:

https://www.poolspaforum.com/forum/index.php?/topic/28846-lowering-total-alkalinity-howto/

 

This process sounds good and I will try it to lower TA but it begs the question:  if aerating raises PH then arent I raising PH every time I use the tub with jets?  Does it go back down?  Otherwise isn’t PH ever increasing with each use?

[RDspaguy 742]

22 minutes ago, sophiemurray said:

can be damaging for the bath.

How? Do you know, or are you just repeating what your dealer said?

The short version is: unless you spill it on your wooden cabinet or vinyl cover, you can't hurt your spa with bleach. It is just chlorine in water.

In this thread alone, there is a century or more of real life in the field experience and we all agree that sodium hypochlorite (aka bleach) is just fine in a spa.

[waterbear 147]

2 hours ago, sophiemurray said:

As far as I know, you don't have to use bleach. It can be damaging for the bath. I have a hot tub at home, and I don't use bleach, never!

Perhaps you should educate yourself a bit more in the field of water chemistry before posting. You obviously don't understand the pros and cons of different chlorine sources and when to use them. My question for you is if you don't use bleach are you using dichlor and if you are are you testing your cyanruic acid level?

Also, not sure if you are aware that the  poster is using bleach as an oxidizer in a bromine tub to activate the bromide bank and not as the primary sanitizer.

Finally, are you aware that bleach is the same as liquid chlorine (sodium hypochlorite)?

 

[waterbear 147]

2 hours ago, mscdman said:

 if aerating raises PH then arent I raising PH every time I use the tub with jets?  Does it go back down?  Otherwise isn’t PH ever increasing with each use?

Yes, No, Yes. However, how fast it rises depends on the TA (which is why I said to get it between 50-70 ppm) and if you have a secondary borate buffer in the water (easy to do with either borax and acid to get the pH back in line, or boric acid which will cause a slight drop in pH but that is self correcting, or a commercial borate product like Gentle Spa or Optimizer). IF you exclusively use an acidic santizer (dichlor, trichlor-which is EXTEMELY acidic), or MPS exclusively as a shock or oxidizer then you would want to have a higher TA (perhaps 80-100 in a spa) so the pH will not drop but you need to closely monitor the TA and add baking soda as it drops. I posted this before but it bears repeating:

THE MAIN CAUSE OF pH RISE IN A POOL OR SPA IS OUTGASSING OF CO2.

THE HIGHER THE TA (CARBONATION IN THE WATER), THE FASTER CO2 WILL OUTGAS AND THE FASTER THE pH WILL RISE.

THE HIGHER THE AERATION OF THE WATER (OZONE SYSTEMS, SALT WATER SANITIZER SYSTEMS, AIR INJECTORS,  AERATION FROM YOUR JETS, 24 HOUR CIRCULATION ON HIGH SPEED, ETC.) THE FASTER CO2 WILL OUTGAS AND THE FASTER THE pH WILL RISE.

THE LOWER YOU PLACE THE pH THE FASTER IT WILL RISE (YOU ARE CONVERTING MORE BICARBONATE IONS, WHICH IS WHAT WE MEASURE AS TA,  INTO CARBONIC ACID, ESSENTIALLY CO2 DISSOLVED IN THE WATER.

[mscdman 11]

@waterbear just undertook that TA lowering procedure via aereation.  It worked!   It took about an hour but after checking TA/acid demand testing/adding PH down/aerate - repeat. I now have the TA at 70 and PH at 7.5.    
 

Now the test will be what happens at next soak and if PH rises significantly. Ill test PH, bromine, and Alkaline before and after soak and what happens after bleach add and report back and see what next steps are

[mscdman 11]

Ok here are numbers post me lowering the TA following the aereation method from 140ppm to 70ppm TA after.  Taylor K2005 kit tested
 

Presoak Values:

2ppm bromine 

7.5 ph

70 Alkalinity

 

After soak with 15 mins jets on & pre bleach

2ppm bromine - Why didn’t this go down?  hmmm

Ph 7.6ish

70 Alkalinity 

 

5 Mins After adding 1oz 10% bleach

Bromine - 6ppm - this should have been higher per the pool math calculations but 6ppm is acceptable 

Ph 7.6-7.7 - good!  No big change from bleach!!

Seems like that bleach rising the ph is now a nothingburger.  However looks like a .1 increase just from 15 mins of usage due to aereation.  So wouldn’t that mean I’m going to have to add PH down then once it reaches above 8 due to aereation/use?

also curious why the bromine levels didn’t rise as much as they should have post bleach   Wierd  getting closer though!!

 

 

[waterbear 147]

15 hours ago, mscdman said:

So wouldn’t that mean I’m going to have to add PH down then once it reaches above 8 due to aereation/use?

Yes. Adding borate will help as might lowering the TA a bit more but it is the nature of the beast. You also need to monitor TA every week or two and when it drops BELOW 50 raise it back to your 'sweet spot' for pH stability. Also, don't try to keep the pH at 7.5. Run it a bit higher (around 7.7-7.8) and you should find it doesn't rise quite as fast. If you are doing water changes every 3 to 4 months (as normally recommended) then you will probably find that if you balance the water on filling TA should be good for the duration. pH adjustments will probably be needed, as will sanitizer adjustments. Santizer might be upon every use if you are doing 1 step or 2 step bromine (sodium bromine and an oxidizer, either as an all in one product or added separately) or 3 step bromine (create bromide band with sodium bromide, bromine tabs in a floater, and 'shocking' with an oxidizer every week or two, depending on spa usage), which should maintain the desired 4-6 ppm bromine between use once the floater is properly adjusted (which takes a bit of patience and trial and error).

 

15 hours ago, mscdman said:

After soak with 15 mins jets on & pre bleach

2ppm bromine - Why didn’t this go down?  hmmm

Do you have a floater with bromine tabs? IF so that's why. Also, if your bromine is around 2 ppm before adding bleach then you need to open the floater more. You want your bromine to be between 4-6 ppm.  IF you are not using a floater but have added sodium bromide to create a bromide bank and are using bleach to oxidize then it's normal for bromine levels to drop.

Finally, are you using the bromine scale on the right hand side of the sanitizer comparator block? This might seem like a stupid question but I once worked at a commercial facility with 2  large pools (55K gal and 60K gal) , 2 (1000 gal) hot tubs, and a 1000 gal kids splash area (water features like dancing fountains and overhead sprays) that drained into an underground tank. All were using liquid chlorine with peristaltic pumps for both chlorine and acid dosing and we were using Taylor K2005 for testing. When I started there I noticed that our FC readings were being listed in the Health Dept. logbook at 3.6 ppm. The K2005 does not have that much resolution for testing chlorine so I questioned one of the CPOs (Certified Pool Operator, which is a training with an exam needed to run a commercial pool or spa) and he grabbed the comparator and showed me where it had a 3 printed on the left (chlorine side) and a 6 printed on the right (bromine side). Needless to say I went to the Manager and explained the situation and also explained about FAS-DPD testing. the K2005 kits were supplemented with the FAS-DPD test and I had to train the other staff that tested water how to properly use both the DPD test and the FAS-DPD test. Remember, these were supposed to be trained commercial pool operators!

[mscdman 11]

19 minutes ago, waterbear said:

Yes. Adding borate will help as might lowering the TA a bit more but it is the nature of the beast. You also need to monitor TA every week or two and when it drops BELOW 50 raise it back to your 'sweet spot' for pH stability. Also, don't try to keep the pH at 7.5. Run it a bit higher (around 7.7-7.8) and you should find it doesn't rise quite as fast. If you are doing water changes every 3 to 4 months (as normally recommended) then you will probably find that if you balance the water on filling TA should be good for the duration. pH adjustments will probably be needed, as will sanitizer adjustments. Santizer might be upon every use if you are doing 1 step or 2 step bromine (sodium bromine and an oxidizer, either as an all in one product or added separately) or 3 step bromine (create bromide band with sodium bromide, bromine tabs in a floater, and 'shocking' with an oxidizer every week or two, depending on spa usage), which should maintain the desired 4-6 ppm bromine between use once the floater is properly adjusted (which takes a bit of patience and trial and error).

 

Do you have a floater with bromine tabs? IF so that's why. Also, if your bromine is around 2 ppm before adding bleach then you need to open the floater more. You want your bromine to be between 4-6 ppm.  IF you are not using a floater but have added sodium bromide to create a bromide bank and are using bleach to oxidize then it's normal for bromine levels to drop.

Finally, are you using the bromine scale on the right hand side of the sanitizer comparator block? This might seem like a stupid question but I once worked at a commercial facility with 2  large pools (55K gal and 60K gal) , 2 (1000 gal) hot tubs, and a 1000 gal kids splash area (water features like dancing fountains and overhead sprays) that drained into an underground tank. All were using liquid chlorine with peristaltic pumps for both chlorine and acid dosing and we were using Taylor K2005 for testing. When I started there I noticed that our FC readings were being listed in the Health Dept. logbook at 3.6 ppm. The K2005 does not have that much resolution for testing chlorine so I questioned one of the CPOs (Certified Pool Operator, which is a training with an exam needed to run a commercial pool or spa) and he grabbed the comparator and showed me where it had a 3 printed on the left (chlorine side) and a 6 printed on the right (bromine side). Needless to say I went to the Manager and explained the situation and also explained about FAS-DPD testing. the K2005 kits were supplemented with the FAS-DPD test and I had to train the other staff that tested water how to properly use both the DPD test and the FAS-DPD test. Remember, these were supposed to be trained commercial pool operators!

First off - great stuff sir.  Always appreciate you time and efforts to the numerous questions on this forum.  Thank you. 
 

to answer a few of your questions I’m currently using a 2-step bromine system.    But I’m thinking some of my bromine reserve needs to be replenished which is why after adding the bleach the bromine didn’t increase much. Yes I am using the bromine scale of the right side of the comparator block. Part of it is me trying to eyeball The color.  So if it’s just a HAIR darker than the 7.5 block but not even close to the next block I assume it’s just barely above 7.5.  
 

last question I promise:  you mention rechecking TA frequently and raising when it falls below say 50ish.    What do you use to raise TA?  PH plus?  TA increaser?