Can't Get Ph Down

[rdefino]

My PH is at 8.0 and little more. I've been adding SPA qaurd PH decreaser for 2 days and the PH hasn't moved. Any thoughts?

[quantumchromodynamics]

What is your Total Alkalinity? If your pH is too high and won't come down, then your TA is too high. You would also get better results if you used muriatic acid rather than dry acid.

Lowering Alkalinity

[rdefino]

What is your Total Alkalinity? If your pH is too high and won't come down, then your TA is too high. You would also get better results if you used muriatic acid rather than dry acid.

Lowering Alkalinity

Well I just check and th PH finally dropped to 7.6.

TA is at 60ppm.

As for the muriatic acid, can I get that Home depot or a hardware store. Also, is that a liquid,and do I just pour it in?

Thanks

[OttawaGreg]

What is your Total Alkalinity? If your pH is too high and won't come down, then your TA is too high. You would also get better results if you used muriatic acid rather than dry acid.

Lowering Alkalinity

Well I just check and th PH finally dropped to 7.6.

TA is at 60ppm.

As for the muriatic acid, can I get that Home depot or a hardware store. Also, is that a liquid,and do I just pour it in?

Thanks

You can get muriatic acid at home hardware/depot. Be VERY careful with it! That stuff is seriously toxic.. but works like a charm.

[rdefino]

You can get muriatic acid at home hardware/depot. Be VERY careful with it! That stuff is seriously toxic.. but works like a charm.

My setup uses an ozanator, will this be alright. What precautions should I take when using it? How long do I have to wait from using it to going in the tub.

Also, how much do I use, is there a reference chart or something?

thanks for the helph

[OttawaGreg]

You can get muriatic acid at home hardware/depot. Be VERY careful with it! That stuff is seriously toxic.. but works like a charm.

My setup uses an ozanator, will this be alright. What precautions should I take when using it? How long do I have to wait from using it to going in the tub.

Also, how much do I use, is there a reference chart or something?

thanks for the helph

I carefully poor 30ml of acid into a plastic container (ice cream, yogurt) that is filled with tap water to dilute. I then add this to the center of my tub with jest on low so not to splash. I tend not to add more then 30ml per treatment then measure the effect a few hours later. You could use the tub probably 30 minutes after adding it.

No issue with ozanator.

Greg

[steev.ca]

I have been having a similar problem with my spa however it has been going on much longer. I have a Genesis Salt water bromine generator system. We just refilled our spa recently (this is the first refill for us) and used a liquid product called "BromeAdd" to add the Sodium Bromide (NaBr) to the water. BromeAdd is 35% NaBr, this was used because the 98% NaBr TruBlu granular product is not available in Canada. I suspect this has caused the high pH however I cannot be sure. After adding many iterations of Sodium Bisulfate (acid to lower pH) to lower the pH and also adding sodium bicarbonate to raise Total Alkalinity, (this is done first when it is required) it seems to remain at 8.4 according to my dipstick reading and 8.0-8.2 according to my local spa dealers test.

TA has been maintained anywhere from 120-180 ppm.

What I am wondering if there is anyone else out there who may be using BromeAdd for their Genesis system, and if they have experienced the same issue with pH after startup?

Cheers,

~Steve

[quantumchromodynamics]

I have been having a similar problem with my spa however it has been going on much longer. I have a Genesis Salt water bromine generator system. We just refilled our spa recently (this is the first refill for us) and used a liquid product called "BromeAdd" to add the Sodium Bromide (NaBr) to the water. BromeAdd is 35% NaBr, this was used because the 98% NaBr TruBlu granular product is not available in Canada. I suspect this has caused the high pH however I cannot be sure. After adding many iterations of Sodium Bisulfate (acid to lower pH) to lower the pH and also adding sodium bicarbonate to raise Total Alkalinity, (this is done first when it is required) it seems to remain at 8.4 according to my dipstick reading and 8.0-8.2 according to my local spa dealers test.

TA has been maintained anywhere from 120-180 ppm.

What I am wondering if there is anyone else out there who may be using BromeAdd for their Genesis system, and if they have experienced the same issue with pH after startup?

Cheers,

~Steve

Your TA is too high; it is causing your pH to be too high. You need to lower it until the pH stays right.

Also, get a good test kit. Test strips are not accurate.

[mzimm]

I have been having a similar problem with my spa however it has been going on much longer. I have a Genesis Salt water bromine generator system. We just refilled our spa recently (this is the first refill for us) and used a liquid product called "BromeAdd" to add the Sodium Bromide (NaBr) to the water. BromeAdd is 35% NaBr, this was used because the 98% NaBr TruBlu granular product is not available in Canada. I suspect this has caused the high pH however I cannot be sure. After adding many iterations of Sodium Bisulfate (acid to lower pH) to lower the pH and also adding sodium bicarbonate to raise Total Alkalinity, (this is done first when it is required) it seems to remain at 8.4 according to my dipstick reading and 8.0-8.2 according to my local spa dealers test.

TA has been maintained anywhere from 120-180 ppm.

What I am wondering if there is anyone else out there who may be using BromeAdd for their Genesis system, and if they have experienced the same issue with pH after startup?

Cheers,

~Steve

Your TA is too high; it is causing your pH to be too high. You need to lower it until the pH stays right.

Also, get a good test kit. Test strips are not accurate.

Hi, this is my first post! I've been having this exact same issue with the PH staying around 8.0. I use dry acid to lower it to 7.4 and the next day its right back at 8.0. My TA is right around 70 right now (keeps getting lower with all the dry acid until I add baking soda to bring it back to around 100).

How do I find my ideal TA to stabilize my PH at around 7.4.

I've also recently added Gentle SPA thinking it would help but still have the same issue.

Without balancing my water here are the details of my fill water: TA: 300, PH 7.2, CH 293, TDS 250 - is this a potential cause of my issue?

The water in the spa (250 gallon) is around 3 weeks old. And using Brilliance for Spas Bromine and testing the water with a good Taylor kit.

Thanks for your help!

Mike

[quantumchromodynamics]

Hi, this is my first post! I've been having this exact same issue with the PH staying around 8.0. I use dry acid to lower it to 7.4 and the next day its right back at 8.0. My TA is right around 70 right now (keeps getting lower with all the dry acid until I add baking soda to bring it back to around 100).

How do I find my ideal TA to stabilize my PH at around 7.4.

I've also recently added Gentle SPA thinking it would help but still have the same issue.

Without balancing my water here are the details of my fill water: TA: 300, PH 7.2, CH 293, TDS 250 - is this a potential cause of my issue?

The water in the spa (250 gallon) is around 3 weeks old. And using Brilliance for Spas Bromine and testing the water with a good Taylor kit.

Thanks for your help!

Mike

The first problem is that you keep adding baking soda to raise the TA to 100. The TA needs to be wherever it is when the pH stays stable at 7.4 to 7.5. That is probably going to be around 40 to 80 ppm.

I also recommend that you use muriatic acid instead of the dry acid.

Use the pool calculator to calculate your CSI. You want to keep it between -0.3 and 0.0 to prevent scaling.

[mzimm]

Thanks for the reply.

Is it for sure OK to keep my TA of around 40-50? Is it hard on the equipment?

I was trying to keep it in the "ideal" range of 80-120 because my dealer told me I must not fall below 80 or else...

So what I should do is adjust the PH to 7.4-7.5 and let the TA do its own thing?

[quantumchromodynamics]

Is it for sure OK to keep my TA of around 40-50? Is it hard on the equipment?

I was trying to keep it in the "ideal" range of 80-120 because my dealer told me I must not fall below 80 or else...

Many dealers do not understand the chemistry involved. It is definitely OK to have a TA of 40 or 50 ppm, if necessary.

The key is to keep your CSI in the -0.3 to 0.0 range. CSI is one of the most underestimated elements of pool and spa water care. (Did your dealer even tell you about CSI?)

Due to your high calcium levels, you are at increased risk of calcium carbonate scaling. Managing your CSI will protect your equipment from corrosion and scaling. I recommend that you try to aim for a CSI of about -0.10 to -0.15.

Use the pool calculator to calculate your CSI.

So what I should do is adjust the PH to 7.4-7.5 and let the TA do its own thing?

You should adjust the pH indirectly by adjusting the TA.

If the pH is constantly too high, then the TA is too high. If the pH is constantly too low, then the TA is too low.

When your TA gets to the right level, your pH will stay at the right level with almost no effort.

[mzimm]

I was messing around with the Pool Calculator. I'm seeing to maintain a CSI of -.10 with my ch=293 I would need ph=7.3, ta=70, with borate=30 (does that sound correct)

I see that there isn't a field on the Pool Calc for Bromine users.

How would bromine effect my CSI reading? Do I zero the CYA and FC being I'm using bromine?

Would adding a field for bromine users in the Pool Calculator be a nice to have formula or does bromine not effect water chem too much?

Thanks

Mike

[chem geek]

Neither the chlorine or bromine readings affect the CSI. Yes, you would zero the CYA reading when using bromine, assuming you've never used Dichlor not even for shocking.

Adding bromine to the pool calculator has been mentioned, but I think Jason will create a spa calculator with different recommended ranges (lower CH and TA, for example) if he adds bromine. Since bromine is usually added with tablets, it doesn't make much sense to have that in the calculator. If you use chlorine to shock and want to know the bromine level, just note that the bromine level is 2.25 times the chlorine level, each measured in their respective ppm. So an FC of 3 ppm is equivalent to 6.75 ppm bromine.

[quantumchromodynamics]

DMH (5,5-dimethylhydantoin) might have an effect on the CSI.

However, I don't think that it has been determined conclusively. One reference shows a pKa of 8.1. Another reference shows a pKa of 9.19, which is almost identical to boric acid (pKa₁ = 9.14, pKa₂ = 12.7)

pKa of DMH = 8.1

pKa of DMH = 9.19

It might be worthwhile adding a DMH correction to the CSI if we can figure out what the correction should be. Someone using a lot of bromine tabs would add a significant amount of DMH after a few months.

For every 10 ppm of bromine supplied by DBDMH, you will get 4 ppm of DMH.

Every 1 ounce of DBDMH added to 100 gallons of water will add 83.72 ppm of bromine and 33.56 ppm of DMH. (This works out to a bromine of 118 % by weight).

Assuming a 0.70 ounce tab, every DBDMH bromine tab will add 58.60 ppm of bromine and 23.49 ppm of DMH to 100 gallons of water.

1 DBDMH bromine tab added to 400 gallons of water will add 14.65 ppm bromine (measured as Br₂) and will add 5.87 ppm of DMH.

Every 1 ounce of BCDMH added to 100 gallons of water will add 99.13 ppm of bromine and 39.74 ppm of DMH. (I counted the chlorine as bromine since it will oxidize bromide to bromine quickly. This gives an effective bromine of 132 % by weight.)

Based on the high pKa, and if the DMH is limited by using MPS or chlorine on a regular basis, the CSI should not be affected too much.

While the DMH will contribute to the TA, it will do so in a way that causes the CSI to calculate higher than it really is, which is less problematic than if it were to cause it to calculate lower than it really was.

I found an interesting alleged fact about DMH:

5,5-dimethylhydantoin (DMH), when added to a water feature containing bromine, inhibits the formation of bromate. http://www.patentstorm.us/patents/6811747/description.html

That would be a good thing as bromine users who have an ozonator might develop bromate from the ozone.

Although bromates are mostly problematic in drinking water. I don't think that there is much risk due to absorption through the skin or via breathing in volatilized bromates.

The same source also had this quote:

Cyanuric acid is also effective at stabilizing bromine. The mechanism by which the cyanuric acid stabilizes bromine is not fully understood, although it is likely that the cyanuric acid "binds" a portion of the bromine present in the water of the water feature, thus lowering the vapor pressure of the bromine. This bound bromine is less susceptible to thermal loss and ultraviolet loss than is unbound bromine. Conventional wisdom in the spa and pool industry at one time held that cyanuric acid should not be used with bromine because, rather than stabilizing the bromine, the cyanuric acid was believed to remove bromine from the system. The removal of bromine, however, only occurs for an initial "bromine demand" resulting from bromine removal by impurities in the cyanuric acid. Once that initial demand is overcome, the cyanuric acid behaves as a bromine stabilizer as discussed above. Thus, when the chemical formulation is used with a water feature sanitized by electrolysis of a bromide salt, an initial "start up" dose of bromine is typically added to satisfy the initial bromine demand of the cyanuric acid. http://www.patentstorm.us/patents/6811747/description.html

Note: You might find that a pH of 7.3 and a TA of 70 won't work because the pH keeps rising. I'm thinking that your pH will be stable at 7.4 to 7.5 at a TA of 50 to 60.

Keep adjusting the TA in small increments based on what the pH does until the pH stabilizes.

[chem geek]

I'm usually skeptical about patent descriptions since those aren't scientific papers and are not peer-reviewed. The patent you referred to also says the following:

Cyanuric acid may also be employed as a buffering agent. Although the buffering properties of cyanuric acid are known (pKa=6.8), cyanuric acid is typically not utilized in buffers for chlorinated water features because cyanuric acid concentrations must be kept relatively low to avoid "chlorine lock"--a condition wherein the sanitizing strength of chlorine drops sharply. NSPI standards consider a cyanuric acid concentration of 30 to 50 ppm to be ideal for chlorinated swimming pools, and state health regulations often set a maximum cyanuric acid concentration for public swimming pools at 100 ppm. At such low concentrations, cyanuric acid does not provide substantial buffering. In contrast to chlorine, when bromine is employed as a sanitizing agent, an equivalent "bromine lock" condition is not observed.

As we know, there really isn't any such thing as "chlorine lock". There is a continual equilibrium of chlorine with CYA (unbound as hypochlorous acid or hypochlorite ion vs. bound as one of several chlorinated isocyanurates). The sanitizing strength of chlorine drops sharply even at lower CYA levels. They also say that at swimming pool concentrations CYA doesn't provide buffering which is not true, though it isn't as strong as the carbonate buffer. For example, in terms of preventing a drop in pH, 50 ppm more TA is roughly equivalent to 80 ppm CYA as described in this post.

It is true that the industry lore about CYA not having any effect on bromine and being silent about DMH doesn't mean that there aren't really effects, though I can't find anything in the scientific literature on this. It would be fairly easy to tell if CYA had a significant effect on bromine by seeing if there is a large drop in ORP when CYA was added. Same with DMH. I'm a bit surprised no one has tried that. One must make sure the probe stays clean since CYA can also have an effect on the probe, but that is easily handled and one can have a control with CYA in the water with no sanitizer for comparison.

[quantumchromodynamics]

I am also skeptical about patent descriptions. I do think that the claims are interesting. I would hope that they would have at least some basis for making them. I would be interested in knowing what references they have for their claims.

In regard to the new pKa that I found, do you think that it is accurate? Do you think that a DMH correction to the CSI is worthwhile? I think that it would be more important for a plaster tub that needed a saturated index.

Also, do you think that it would be worthwhile to add 30 ppm of cyanuric acid to a bromine tub just in case it does provide some stabilization? I don't think it would hurt.

It would be good to know about cyanuric acid's effect on bromine, especially where the person is using dichlor to shock their bromine tub. "Granular bromine" is a mix of dichlor and sodium bromide. People using this product could accumulate a lot of cyanuric acid after using the product for a while.

PQ Spa Bromine Granules

510g/Kg Available Chlorine present as Sodium dichloroisocyanurate

150g/Kg Sodium Bromide

Spa Essentials Brominating Concentrate

Chemical Name..................................CAS#............... Wt.%

Sodium dichloro-s-triazinetrione....2893-78-9............. 82.5

Sodium bromide............................7647-15-6..............14.7

[quantumchromodynamics]

I went to the library today to look up the pKa of 5,5 dimethyl hydantoin (C₅H₈N₂O₂).

According to "Lange's Handbook of Chemistry", 16th edition, copyright 2005, the pKa of 5,5 dimethylhydantoin is 9.19. Molecular weight = 128.129220 grams per mole.

5,5 dimethyl hydantoin (C₅H₈N₂O₂).

BCDMH (C₅H₆BrClN₂O₂)

[chem geek]

So DMH has a pKa pretty close to boric acid. So for practical purposes, it doesn't show up in the TA test at normal spa pH so would not influence the CSI calculation. 50 ppm Borates (measured as 50 ppm Boron) at a pH of 7.5 only increases the TA by about 5 ppm and that's quite a lot of boric acid. It would probably take quite a while for the DMH to build up to an equivalent molar concentration. It's around 328 ppm cumulative FC equivalent so around 82 days at 4 ppm FC per day equivalent usage.

As for CYA in a bromine tub, I'm still skeptical whether it would make a difference in bromine concentration and I'm not so sure you need that concentration to be that much lower since bromine is a weaker oxidizer than chlorine and might need to be unstabilized in order to kill pathogens quickly enough. So unless we know something more definitive, I'd keep CYA out of a bromine tub, at least not intentionally adding it, though it probably doesn't matter.

[quantumchromodynamics]

There is such a thing as Dibromoisocyanuric Acid C₃HBr₂N₃O₃ and Tribromoisocyanuric Acid (C₃Br₃N₃O₃). Therefore, bromine will combine with cyanuric acid.

I don't think that we can automatically assume that all of the bromine will dissociate when the product is dissolved in water.

Tribromoisocyanuric Acid (C₃Br₃N₃O₃).

Dibromoisocyanuric Acid. C₃HBr₂N₃O₃

[chem geek]

It's around 328 ppm cumulative FC equivalent so around 82 days at 4 ppm FC per day equivalent usage.

I forgot that there are two bromine or chlorine or bromo/chloro combination with the DMH so the FC equivalent is actually double what I wrote above, so that doubles the time it takes to build up. It basically means that the buildup of DMH will have a negligible affect on TA and therefore CSI.

As for the dibromoisocyanuricacid and tribromoisocyanuric acid, I did know that those existed in solid form, but don't know the equilibrium for them with respect to hypobromous acid. You are right that we shouldn't assume they aren't in equilibrium such that there could be an issue lowering effective bromine concentration -- I just don't know and have not found pK numbers for the hydolysis constants. Again, it should be pretty easy to see the effect by measuring ORP and seeing if it drops noticeably when adding CYA to the water (having a control without bromine that just has CYA added to the water).

[quantumchromodynamics]

If a person added 4.06 ppm bromine per day from bromine tabs, they would add a cumulative total of 1481.6 ppm bromine over 1 year. That would add 592.64 ppm dimethyl hydantoin, which would have the same effect on TA as 50 ppm Borate.

I think that it would be good if we can find the pK numbers for the hydrolysis constants for bromine with cyanuric acid and for bromine with Dimethyl hydantoin.

Since DMH and Cyanuric acid have almost the exact same molecular weight, they would have an equal molarity for the same ppm concentration.

Even if the equilibrium constants for bromine with DMH are a fraction of what they are for chlorine with cyanuric acid, there would still be a significant effect.

[Pacopaco]

Please explain the 

acronyms or abbreviations.

[waterbear]

Please start a new thread in the hot tub water chemistry section and list which acronyms and abbreviations you want explained. Thanks!