Borates With Swg

[Florida Penguin]

I have been getting used to my new pool with my AquaPure 1400 SWG. I understand the reason for the higher CYA levels (60-80) and the lower TA level (70-80).

I am now focusing in on the pH issue, and the prevaling view is to keep the pH 7.5-7.6 range.

I can see how my pool is behaving with the pH...goes to 7.8...I add acid....drops to 7.2.....kinda swings back and forth.

I have read a little about the borate/boric acid buffer (50ppm). Can someone (....Chemgeek?) expand on this a bit more. What are the pluses and minuses about this.

I am always concerned about adding something that wont' go away easy to my pool, so I need to learn more about the borate issue.

Thanks!

[waterbear]

I have been getting used to my new pool with my AquaPure 1400 SWG. I understand the reason for the higher CYA levels (60-80) and the lower TA level (70-80).

I am now focusing in on the pH issue, and the prevaling view is to keep the pH 7.5-7.6 range.

I can see how my pool is behaving with the pH...goes to 7.8...I add acid....drops to 7.2.....kinda swings back and forth.

Try adding less acid to only drop the pH to about 7.6. You will find that you are not adding acid as frequently.

I have read a little about the borate/boric acid buffer (50ppm). Can someone (....Chemgeek?) expand on this a bit more. What are the pluses and minuses about this.

I am always concerned about adding something that wont' go away easy to my pool, so I need to learn more about the borate issue.

Thanks!

Borates have many pluses and really no minuses (except for pehaps a bit of toxicity to dogs if the dring a LOT of water to the pool--then again, borates would not be the only thing I would worry about here!) There are many borate products on the market for pool use--Proteam Supreme Plus, Bioguard Optmizer, Poollife Endure, Guradex Maximizer to name a few plus several salt and 'mineral' mixes for salt water chlorine generators that contain borates--Natural Chemisty's Salt water Magic, Bioguard Mineral Springs, Haviland (Proteam) Ocean Breeze Salt Suport to name a few. As you can see borates are an established pool additive that is being sold by several major chemical companies. The will allow you to run your generator at a lower output percentage (because of the lower chlorine demand) which translates into better pH stability and longer cell life besides the secondary borate buffer they introduce into the water that really helps lock the pH around 7.6- 7.7. Borates also 'soften' the water (which is why they are used in laundry products). Borates 'won't go away easy' but then again that is a plus because it means that you only have to add them when you have to add salt and CYA, which 'don't go away easy' too.

Borates are also being used in cal hypo shocks and in trichlor tabs ( the high tech ones from several manufacturers) because of the benefits of being algaestatic, pH buffering, and lowering chlorine demand.

[Florida Penguin]

Thanks. Two follow up questions:

1) Can you use the Laundry "20 mule team borox"

2) How do you monitor the borate level?

Thanks!

[waterbear]

Thanks. Two follow up questions:

1) Can you use the Laundry "20 mule team borox"

Yes, I do. Borax is borax. Just remeber that muriatic acid needs to be added to compensate for the pH rise from the borax and to create the boric acid/borate buffer. The commercial products (At least the Proteam/Haviland ones) are mixtures of sodium tetraborate pentahydrate and boric acid so they do not affect the pH when added to the water.

3/4 lb (12 oz) 20 mule team (sodium tetraborate decahydrate) and 6 oz muriatic acid will raise 1000 gallons 10 ppm borates.

3 3/4 lbs (60 oz) 20 mule team and 30 oz of muriatic acid will raise 1000 gal 50 ppm.

Remember that 20 mule team comes in a 76 oz (4 3/4 lb) box! (the green box)

Calculate the amount of each you need (do weight out the borax and measrue the acid! I use a kitchen scale for my pool chems) and add 1/2 the acid then 1/2 the borax and brush, add the remaining acid and borax and brush. Pump should be running. Circulate for 48 hous and check pH, adjust it down to 7.6 if higher. It probably will be pretty close. If it's any lower than 7.0 then start aerating or adding more borax to bring it up.

2) How do you monitor the borate level?

Easiest way is test strips. I have found the LaMotte borate strips easier to read than the Proteam or Aquachek. Initially get your borates to 50 ppm. Check them every so often (I check mine monthly) and when they drop to 30 ppm add more borax and acid to bring them back up to 50 ppm.

Thanks!

HTH

[Florida Penguin]

Follow-Up-

I am adding my 20 Mule Team Borox as outlined above.

My calculations are based on a pool of about 12,000 gal.

I have thus far adding 6 boxes of borox (@ 76 oz per box) and the appropriate HCl (about 4.75 cups per box of borox).

I have done this over about 48 hrs.

I am waiting to get my test strips for boric acid before going any further (...I think I will need another 4 boxes to get to the 50ppm goal).

My pH is actually pretty good at this point....7.6-7.7 range.

However, my TA has gone from 100 to about 180 (or more, just based on color test stips).

Should I be concerned? And how does one lower the bicarb level (TA)? My initial thought is more acid (so long as the pH is OK).

I await a response from pool chemistry Gods (? Waterbear ???....ChemGeek????)

Thanks!

[Florida Penguin]

From ChemGeek (from his post some time ago about TA and pH)

"So the procedure for lowering TA most effectively is to first lower the pH to around 7.0 -- the lower the pH, the faster the outgassing of carbon dioxide, but you don't want to damage vinyl liners or pool equipment (metal) so 7.0 is a practical lower limit. You then aerate the water as much as you can -- using an air compressor with a nozzle that produces lots of tiny bubbles and putting that in the deep end works really well. Turning on waterfalls, fountains, showers, etc. also works. Even turning up the eyeballs in the returns helps. Aeration makes the pH go up with no change in Total Alkalinity (TA) (you remove carbon dioxide via H2CO3 --> H2O + CO2 so are removing carbonic acid so you are removing BOTH carbonate which increases TA AND acid, hydrogen ions, which decrease TA and these exactly cancel each other out). When the pH rises to 7.2 (or more), you add acid to lower the pH back down to 7.0 and repeat this process until the TA is where you want it. Then, just aerate without adding acid to have the pH rise to where you want it -- usually around 7.5"

-Ok... I think I get it.....the TA (total alkalinity) is really a measure of the pH buffers in the pool...mostly bicarb buffer, but it can also include other buffer systems (like boric acid).

I tried looking up the pKa for boric acid, but it is complicated, and apparently at the low concentrations that we use in pool, the borate is in a mono-hydrate phase, so the pKa of 9.1 of boric acid (not the tetraborate in Borax) doesn't really apply. {I think I got this right, but it has been a while since chemistry classes)

Anyway, back to the nuts and bolts of running a pool-

1) What is the harm of higher TA levels as long as the pH is OK (7.5-7.6 ish)?

2) (same question, differnet way to ask it)...what is the rush to lower the TA as long as the pH is closely monitored and kept in the appropriate range?

3) So once the borate level is around 50 ppm, how much lower can we run the FC (...my target is about 5% of the CYA level....what should that be with borate in the pool?)

Thanks-

Rich H.

[Florida Penguin]

Hmmmm....I seem to be answering my own questions tonight with my additional searches....

Again from ChemGeek (7/07)-

There are many over-simplifications or direct falsehoods the pool industry has with regards to pool water chemistry. One is that higher TA makes pH more stable. That is only half-true. Higher TA that comes from carbonates, which is the largest component in TA (another is a fraction of the CYA level and even less is the Borates level) is a source of rising pH itself. The reason is that pools are intentionally over-carbonated, just like a beverage, since they have more carbon dioxide dissolved in the water than would be naturally found from exposure to air. This over-saturation is done when you add baking soda or Alkalinity Up upon pool startup though even fill water has some TA.

The reason for having this over-saturation of carbonates is twofold. First, it does buffer pH FROM OTHER SOURCES of pH change, but it has the side effect of being a source of rising pH in its own right. Second, the carbonates portion of TA is necessary in plaster/gunite pools to prevent corrosion (technically dissolving) of such surfaces.

So a higher TA makes sense when using an acidic source of chlorine such as Trichlor (or even Dichlor which is technically acidic when one takes into account chlorine usage). It does not make as much sense to have high TA when using a pH neutral source of chlorine such as bleach or chlorinating liquid. I say "pH neutral" because though the initial addition of bleach or chlorinating liquid makes the pH rise, the usage of the chlorine (breakdown from sunlight, oxidation of organics, killing algae or bacteria, etc.) is acidic so the net result is very nearly pH neutral.

So it has been the recommendation on this forum for a while to lower the TA level if you are using bleach or chlorinating liquid and find a tendency for the pH to rise. The pH rises more quickly at higher TA and lower pH and with more aeration. This chart shows the relative rate of carbon dioxide outgassing at various pH and TA levels. This is a relative rate since the actual rate depends on the amount of aeration. These relative numbers would correspond to the amount of acid you needed to add each week. This chart shows the relative rise in pH and shows the fact that the lower TA is a smaller source of pH rise, but the lower TA also buffers the pH less so these two factors somewhat cancel each other out, but there is still a small net improvement at lower TA levels.

As for your question of side effects, a lower TA is more corrosive to plaster/gunite so those with such pools would need to either increase the Calcium Hardness level or the target pH or both to compensate. Since a higher pH also results in less of a tendency to rise further, most people lower the TA level and target a somewhat higher pH, such as 7.7 instead of 7.5.

As for how low to go, I wouldn't go below 50 ppm because you do want some pH buffering in the pool and also may need some carbonates if you have plaster/gunite. If you had much lower TA, then a relatively small amount of acid (say, from Trichlor or Muriatic Acid) could make the pH move more than expected and if the pH got low then that could corrode metal as well as plaster/gunite. Since you have a vinyl liner and don't need the calcium nor the carbonates to prevent corrosion, the only risk you are taking is if some acid or base is added to your pool. Even relatively soft water will have some TA in it and the CYA itself contributes to TA, but what you are seeing just confirms the theory that we've been saying for a while.

Pools with SWG systems (which isn't the case with your pool) have a particularly hard time with rising pH because the hydrogen gas bubbles generated in the SWG cell essentially pull the carbon dioxide out of the pool through aeration and that causes the pH to rise quickly. Lower TA helps such pools, but so does the use of Borates since they act as an additional pH buffer and are also an algaecide that let SWG users lower their SWG output which reduces the outgassing and therefore the tendency for the pH to rise.

So, I think this means:

1) You need some (mostly bicarb) buffer to keep the plaster in the pool walls, not dissolved in the water

2) You need some buffer (again mostly bicarb) to keep the pH stable and prevent wild swings.

3) The lower bicarb in a SWG pool, the less CO2 available to blow off with the H2 bubbles, so the lower the bicarb (lower TA), the less rise in pH you get from generating chlorine.

4) If TA gets too high, it will combine with Ca++ in the pool water and precipitate out and form cloudy water and deposits on the walls...

Am I close?

Still, no luck on my last question-

So once the borate level is around 50 ppm, how much lower can we run the FC (...my target is about 5% of the CYA level....what should that be with borate in the pool?

Thanks-

Rich H.

[waterbear]

Hmmmm....I seem to be answering my own questions tonight with my additional searches....

Again from ChemGeek (7/07)-

There are many over-simplifications or direct falsehoods the pool industry has with regards to pool water chemistry. One is that higher TA makes pH more stable. That is only half-true. Higher TA that comes from carbonates, which is the largest component in TA (another is a fraction of the CYA level and even less is the Borates level) is a source of rising pH itself. The reason is that pools are intentionally over-carbonated, just like a beverage, since they have more carbon dioxide dissolved in the water than would be naturally found from exposure to air. This over-saturation is done when you add baking soda or Alkalinity Up upon pool startup though even fill water has some TA.

The reason for having this over-saturation of carbonates is twofold. First, it does buffer pH FROM OTHER SOURCES of pH change, but it has the side effect of being a source of rising pH in its own right. Second, the carbonates portion of TA is necessary in plaster/gunite pools to prevent corrosion (technically dissolving) of such surfaces.

So a higher TA makes sense when using an acidic source of chlorine such as Trichlor (or even Dichlor which is technically acidic when one takes into account chlorine usage). It does not make as much sense to have high TA when using a pH neutral source of chlorine such as bleach or chlorinating liquid. I say "pH neutral" because though the initial addition of bleach or chlorinating liquid makes the pH rise, the usage of the chlorine (breakdown from sunlight, oxidation of organics, killing algae or bacteria, etc.) is acidic so the net result is very nearly pH neutral.

So it has been the recommendation on this forum for a while to lower the TA level if you are using bleach or chlorinating liquid and find a tendency for the pH to rise. The pH rises more quickly at higher TA and lower pH and with more aeration. This chart shows the relative rate of carbon dioxide outgassing at various pH and TA levels. This is a relative rate since the actual rate depends on the amount of aeration. These relative numbers would correspond to the amount of acid you needed to add each week. This chart shows the relative rise in pH and shows the fact that the lower TA is a smaller source of pH rise, but the lower TA also buffers the pH less so these two factors somewhat cancel each other out, but there is still a small net improvement at lower TA levels.

As for your question of side effects, a lower TA is more corrosive to plaster/gunite so those with such pools would need to either increase the Calcium Hardness level or the target pH or both to compensate. Since a higher pH also results in less of a tendency to rise further, most people lower the TA level and target a somewhat higher pH, such as 7.7 instead of 7.5.

As for how low to go, I wouldn't go below 50 ppm because you do want some pH buffering in the pool and also may need some carbonates if you have plaster/gunite. If you had much lower TA, then a relatively small amount of acid (say, from Trichlor or Muriatic Acid) could make the pH move more than expected and if the pH got low then that could corrode metal as well as plaster/gunite. Since you have a vinyl liner and don't need the calcium nor the carbonates to prevent corrosion, the only risk you are taking is if some acid or base is added to your pool. Even relatively soft water will have some TA in it and the CYA itself contributes to TA, but what you are seeing just confirms the theory that we've been saying for a while.

Pools with SWG systems (which isn't the case with your pool) have a particularly hard time with rising pH because the hydrogen gas bubbles generated in the SWG cell essentially pull the carbon dioxide out of the pool through aeration and that causes the pH to rise quickly. Lower TA helps such pools, but so does the use of Borates since they act as an additional pH buffer and are also an algaecide that let SWG users lower their SWG output which reduces the outgassing and therefore the tendency for the pH to rise.

So, I think this means:

1) You need some (mostly bicarb) buffer to keep the plaster in the pool walls, not dissolved in the water

Calcium hardness is what does this. If you are running a lower TA then you simply increase the CH to compensate. If you decide to run your TA in the 60-80 ppm range along with 30 to 50 ppm borates then keep your CH around 300 ppm. YOU NEED A GOOD TEST KIT. I RECOMMEND A TAYLOR K-2006 (NOT THE K-2005!)

2) You need some buffer (again mostly bicarb) to keep the pH stable and prevent wild swings.

Carbonate buffer level (TA) is determined by the type of chlorine, either stabilized or unstabilized. Unstablilized chlorine (such as from a SWG, liqiud chlorine, or cal hypo) require a much lower TA for pH stability than stabizilized chlorine (trichlor and dichlor).

3) The lower bicarb in a SWG pool, the less CO2 available to blow off with the H2 bubbles, so the lower the bicarb (lower TA), the less rise in pH you get from generating chlorine.

You basically have the idea. TA is a test for the measurable bicarbonates and carbonates in the water. The other part of the carbonate buffer system is carbonic acid (which is not measurable). Carbonic acid is, for our purposes, the same as carbon dioxide dissolved in water (think club soda). Ariation drives this off (think shaking up a bottle of club soda to make it go flat). This means less carbonic acid (key word acid) and more alkaline carbonates and bicarbonates and the pH rises. The less carbonates and bicarbonates in the water the less carbonic acid at the equilbrium point so less CO2 dissolves so less outgassing. Also, keep you pH at 7.6 and when it hits 7.8 lower it to 7.6 and not lower. This will also minimize acid use and pH rise. The lower the pH the faster CO2 will outgas because the higher the carbonic acid in the water.

4) If TA gets too high, it will combine with Ca++ in the pool water and precipitate out and form cloudy water and deposits on the walls...

Yes, it forms calcium carbonate. This is most likely when the pH is high. It can also cause scale deposits on the pool itself. Scale is also calcium carbonate. Clouding is most common when shocking with cal hypo (calcium hypochlorite) and the TA is high or when adding bicarb to raise the TA and the calcium levels are high and the bicarb is added too fast or not diluted enough. Not a bit problem if calcium precipitation causes the water to cloud. Just drop the pH to about 7.0 and it will redissolve then aerate the water to bring the pH back up. Scale deposits on the pool are a different story and often require draining and acid washing. To avoid them keep close tabs on your pH and don't let it get above 7.8

Am I close?

(with an english accent) "By George, I think He's got it!"

Still, no luck on my last question-

So once the borate level is around 50 ppm, how much lower can we run the FC (...my target is about 5% of the CYA level....what should that be with borate in the pool?

Thanks-

Rich H.

I's a pool, not rocket science! Keep it simple! Richard (chemgeek) and I are on the same page and I know him. If you have your CYA in the 60-80 ppm range then practical experience has told us that keeping your FC at about 4 ppm will give you a trouble free pool with a SWG. Borates will not allow you to run at a lower FC but they will reduce your overall chlorine demand. This means that you can set your SWG to a lower output percentage to maintain the same FC level or, if you are manually chlorinating, you will need less chlorine to maintain the same FC level.

The most important thing you need to do is GET A GOOD TEST KIT and NOT STRIPS (except for salt and borates).

I've sent you a PM that should be helpful.

[Florida Penguin]

Thanks- You guys are awesome at this.

I totally agree with your point on test stips. I am using the TF-100 test kit set (which I think is very similar to the Taylor K-2006). The FAS-DPD test alone is worth the price of admission! Even the liquid OTO chlorine test is almost useless when compared to the FAS-DPD test.

I wish there was a better test for the borates. I got my shipment of LaMotte test strips today (...they seemed to get better marks on these posts than the Aquacheck ones)....and my pool has either 30ppm or 50ppm boriates....I can't tell the difference!

I guess it doesn't have to be that precise.

However, I did go swimming in the pool. Although it is hard to remember exactly what the pool water was like before the borates, but I really think adding the borates really makes a noticable difference. It is hard to describe, but the best way I can explain it is this: When you are in the pool, place the palms of your hands down on top of the water. Then push down on top of the water. The water just feels softer, like less surface tension. It almost has a "velvetity" feel to it. After drying off, my skin (most noticeable on hand and hair) don't seem as dryed out...and actually feels smoother.

Anyway, my last point is a bit of skepticism on your explanation for the lower clorine demand with borates. I think you and ChemGeek tried to figure this out back during your great borate experiment. I have having trouble accepting your explanation. There is no clear mechanism to explain how the chlorine lasts longer in a pool with borates. (As chemgeek pointed out, it is really all about the UV light breaking down the chlorine. Unless the pool has alot of alge, etc., in it to start...but we will assume a clean pool for this discussion). So I don't understand how the SWG works less if I set the FC to be a certain level (Lets say FC of 4) either with or without borates. (Unless we just accept there is an unknown mechanism at play to somehow slow down the loss of chlorine)

Thanks again-

You guys have been a tremendous help!

-Rich H.

[waterbear]

Thanks- You guys are awesome at this.

I totally agree with your point on test stips. I am using the TF-100 test kit set (which I think is very similar to the Taylor K-2006). The FAS-DPD test alone is worth the price of admission! Even the liquid OTO chlorine test is almost useless when compared to the FAS-DPD test.

Excellent choice of testkit!

I wish there was a better test for the borates.

IF you can find it, Proteam does have a borate titration test. It is a bit tricky to do but if done right will be more accurate than the strips. Then again, the amount of precision needed for the borate test is not that great so I don't know if it really justifies spending the $50 or so the Proteam borate testkit costs.

I got my shipment of LaMotte test strips today (...they seemed to get better marks on these posts than the Aquacheck ones)....and my pool has either 30ppm or 50ppm boriates....I can't tell the difference!

If you think the LaMotte strips are hard to read then get some of the Proteam or Aquachek! The LaMotte are MUCH better!

I guess it doesn't have to be that precise.

Nope!

However, I did go swimming in the pool. Although it is hard to remember exactly what the pool water was like before the borates, but I really think adding the borates really makes a noticable difference. It is hard to describe, but the best way I can explain it is this: When you are in the pool, place the palms of your hands down on top of the water. Then push down on top of the water. The water just feels softer, like less surface tension. It almost has a "velvetity" feel to it. After drying off, my skin (most noticeable on hand and hair) don't seem as dryed out...and actually feels smoother.

Borates do create many subjective differences in the water. Did you notice the 'sparkle'?

Anyway, my last point is a bit of skepticism on your explanation for the lower clorine demand with borates. I think you and ChemGeek tried to figure this out back during your great borate experiment. I have having trouble accepting your explanation. There is no clear mechanism to explain how the chlorine lasts longer in a pool with borates. (As chemgeek pointed out, it is really all about the UV light breaking down the chlorine. Unless the pool has alot of alge, etc., in it to start...but we will assume a clean pool for this discussion). So I don't understand how the SWG works less if I set the FC to be a certain level (Lets say FC of 4) either with or without borates. (Unless we just accept there is an unknown mechanism at play to somehow slow down the loss of chlorine)

Thanks again-

You guys have been a tremendous help!

-Rich H.

I still believe that, since borates are algaestatic, the lowered chlorine demand is because of the borates taking care of any nascent algae blooms so the chlorine doesn't have to. Remember, at the normal chlorine and CYA levels we keep we are not preventing algae from starting, only killing it quickly as soon as it does. This consumes chlorine. This theory also explains why chlorine demand goes up in summer with more sunlight and higher temps...once again favorable factors for algae blooms.

[bebfoo]

Can one of you chem gurus explain how the recommended level of borax don't seem to jive with my calculations of ppm:

1000 ppm is defined as:

1 gram per 1 liter of liquid.

So 50 ppm = 0.05g per 1 liter

1,000 gallons = 3,785 liters

0.05g/1L = X/3785L

so X = 189g, or 6.67 oz of borax per 1,000 gallons to get to 50ppm of borates

But everything here, and the pool calculator shows that it requires 59 oz per 1,000 gallons.

Is this due to the difference due to molecular weights of the remaining borates after they are converted by the acid (HCL) in the pool? Or I am making a mistake in my calculations?

I got a bit freaked out when I thought I may have just dumped 10X too much borax into my pool. I am still waiting on borate test strips, so I know I should have waited and tested before adding the entire amount recommended by the calculator.

I know just enough about chemistry to be dangerous.