The Great Tetraborate Experiment!

I have been toying with the idea of adding borax to 50 ppm to see exactly what effect, if any, it would have on stabilizing pH. My borate test strips arrived last night so today I tested my water:
FC 5 ppm
CC 0 ppm
pH 7.6
TA 120 ppm (before stabilizer correction)
TA 97 ppm (after stabilizer correction)
CH 220 ppm
CYA 70 ppm
Salt 3500 ppm (used the readout on my Aqualogic which is usually about 100 ppm high so I am estimating about 3400 ppm which is where I was last Friday when I tested it)
Borates 15 ppm (measured with AquaCheck borate test strip. I have used Borax in the past to raise pH)

Today I added 1 box (4 lbs, 12 oz.) 20 mule team and 1 pt muriatic acid to offest the pH rise. (might have to add more acid. I am being conservative, based on the recommendations for Proteam Supreme)
I will test the water in a few hours for pH, TA, and borates.
According to Bleachcalc this amount of borax should raise my pool to 50 ppm but the dosing chart for Proteam Supreme requires a lot more, and the pentahydrate uses less by weight than the decahydrate (20 mule team).

I have been conversing with chem geek (Richard) about the dosing and these discrepancies. The aquacheck test strips are designed for testing Proteam Supreme. We shall see what the outcome is.

My main purpose in this experiment is to see if I get less pH rise with my SWG by adding the tetraborates. (or a slower pH rise). Currently it takes a little over 2 weeks for my pH to hit 7.6 from 7.2. I add 1 1/2 pts. acid every three weeks which lowers me back down to 7.2. I want to see if the borates will hep keep the pH more stable as claimed. Many of the SWG monthly mixes contain tetraborates supposedly for this reason along with boric acid to offset the high ph...adding muriactic acid will form boric acid in the water so this just eliminates that step. I know NaturalChemisty's Salt Water Magic contains the tetraborates and I will bet that Mineral Springs by Bioguard does also.

I will post my results in this thread as they become available. This might turn out to be useful info or a bunch of junk....don't really know yet.

I have never used borax and have a constantly creeping PH. Will be very interesting to follow along.

Just checked my water and borates hadn't moved...still reading 15 ppm. If the proteam dosing chart is the correct one then I only added about another 6 ppm which won't show up on the test strips.
pH was off the scale. Added another quart of acid....in line with Proteam recommendations (and my acid demand test in my Taylor kit) so I will wait a while and retest. Gotta buy some more borax also.
So far this looks like what Richard and I expected and might point to a dosing error in BleachCalc.

ok, tested borates and pH.....borates still reading 15 ppm and pH is at 7.6.....so 1 box of borax takes about 1 1/2 qts (48 oz) acid to neutalize the high pH. This is exactly in line with the Proteam dosing which says 10 oz. acid per pound. I put in 4.75 lbs (contents of one box) and it took 48 oz acid to bring the pH back to 7.6.

After I took the readings above I added 2 more boxes and a half gallon of acid. This was about 45 minutes ago and I just retested
Borates are now reading about 40 ppm (test strip color is right between the 30 and 50 ppm reading) and this is in line with the Proteam dosing and taking the weight difference needed for borax vs. supreme (.75 by weight of pentahydrate needed to achive the same level as the decahydrate.) the three boxes I put in (14.24 lbs) is pretty much the same as 10 lbs. of pentahydrate which will give me a ppm increase of about 23-24 ppm for my pool. Since I started with a base reading of about 15 ppm and am now reading about 40 ppm this is all in line.

The pH is testing at 7.5.

It's getting dark now so I will let the pool circulate overnight and continue tomorrow. My goal is to reach about 50 ppm borates. I figure it should take me about 1 1/2 to 2 boxes more to do it and maybe another 2-3 qts. of acid.

restested my water this morning
FC 5 ppm (no change)
CC 0 ppm (no change)
pH 7.5 (no change)
TA 120 ppm (before stabilizer correction) (no change)
TA 97 ppm (after stabilizer correction) (no change)
CH 220 ppm (no change)
CYA 70 ppm (no change)
Salt 3600 ppm (It is hotter today, the pool water is at 92 degrees so this might be the reason for the higher salt reading...once again using the display on the Aqualogic)
Borates about 40 ppm (measured with AquaCheck borate test strip) (no change)


I added 2 more boxes of borax and 1 quart acid.

Restested pH and borates
pH is off the scale so I added another quart of acid and will retest in a bit.
Borates reading a bit higher than 50 ppm but not as high as 80 ppm. I guess 1 and 1/2 boxes would have been perfect. Once I get the pH corrected I am going to turn on the spllover and dump the spa water into the pool. I will let the system circulate for several hours and then recheck the borates. It might be just enought dilution to get me right on the 50 ppm mark!

Evan, are the borates supposed to stabilize PH even if alk is high?

borates will add about 10 ppm increase in TA for each 30 ppm. I did not see that in my pool so far....I will retest TA once I get the pH stabilized. I do not know what effect they will have at high levels of TA. Chem geek might be better able to answer that. My main goal with this is to see if my pH remains more stable and if my need for acid decreases. It will really take a few months of monitoring this to determine if it was worth it.

Finally got the pH down to 7.4. It took 3 quarts of acid to neuralize 2 boxes of borax. This is pretty much in line with the Proteam recommendation. I have turned on the spillover and will do more water testing late afternoon.

One thing I have noticed is that the water is so clear it actually seems to sparkle. I know this is just subjective but I really can't explain it any other way. Also, the feel of the water is 'silkier'. I suspect that this is because it is closer to the isoelectric point of the human body. I am starting with a salt water pool so to notice a subjective difference in feel is interesting. It actually leaves a 'soft' feeling on the skin when it drys. I guess this is the same effect of bathsalts which often contain borax.

Retested the water:
FC 5 ppm (no change)
CC 0 ppm (no change)
pH 7.4
TA 120 ppm (before stabilizer correction) (no change)
TA 97 ppm (after stabilizer correction) (no change)
CH 220 ppm (no change)
CYA 70 ppm (no change)
Salt 3600 ppm (once again using the display on the Aqualogic. The pool temp has come down some but since the aqualogic acutally uses conductivity to determine the salt readout the addition of the tetraborates might have caused this 100 ppm increase. I will check a sample with the salt meter at work)
Borates about 50 ppm, perhaps slightly higher (measured with AquaCheck borate test strip) (The dilution seens to have worked!)

I am a bit surprised that I see no increase in TA but then again I started the process with the pH at 7.6 and it is now at 7.4 so that might account for it.

Now it's going to be just monitoring the pH and see if there is any difference in the speed and amount of pH rise over time and the amount of acid needed to correct it. I will keep you posted.

restested today....all basically the same
FC 5.5 ppm
CC 0 ppm (no change)
pH 7.5
TA 120 ppm (before stabilizer correction) (no change)
TA 97 ppm (after stabilizer correction) (no change)
CH 220 ppm (no change)
CYA 70 ppm (no change)
Salt 3700 ppm (once again using the display on the Aqualogic.
Salt 3700 ppm (salt meter at work)
SAlt 3800 ( Taylor salt test kit)
It is interesting that my salt reading went up since adding the borax. Will have to ask Chem geek about this!
Borates about 50 ppm, Pretty much right on the money! (measured with AquaCheck borate test strip)
Also did a check for nitrates and nitrites....0 ppm for both
phosphates >1000 ppm....off the scale (probaby between 2000-3000 ppm based on dilution results (Hach phosphate test kit, colorimetric)
water is clear, has always been clear, never had algae, never had CC, never used an algaecide!
Since I have no nitrates ro nitrites, phosphates would be a limiting factor for my pool with algae growth... Guess I never had a problem because I keep on top of the chemsitry! Once again I thinik this proves tha chlorine is the best defense at keeping algae away!

Gonna do my daily pH and Cl checks and see how things go this week.

Great Experiment Evan!

I've been running 30-50 ppm Borates this year, and agree with your assesment on the feel and look of the water.

What would you impose for an upper limit on Borates? Is there a point of dimminishing returns above 50 ppm? What about 100? (Man Logic at its best; if 50 ppm is good, then 100 ppm must be better) ;)

All the info I have been able to find on tetraborates seem to indicate that 30 ppm is where the algaesatic properties become effective and that after 50 ppm there seems to be not that much additional benefit. I don't know about any other implicatons of running a higher boron level.

Weekly pool test....not much had changed
FC 5.0 ppm
CC 0 ppm (no change)
pH 7.5 (Usually up to about 7.6 after a week)
TA 120 ppm (before stabilizer correction) (no change)
TA 97 ppm (after stabilizer correction) (no change)
CH 220 ppm (no change)
CYA 70 ppm (no change)
Salt 3600 ppm (once again using the display on the Aqualogic.
Salt 3550 ( AquaChek White salt test strip)
Borates 50 ppm

Pool is clear, clean, and sparkling. Have company for the week. My Nephew, his wife, 1 grand niece and 2 grand nephews are coming in Sunday so the pool will be getting a lot of use. We will see what happens.

Okay, another week has passed (2nd week of experiment) and I had family visitng (Nephew, his wife, grandniece, and 2 grandnephews) this week so pool got constant use daily! Here are the numbers:

Borates 50 ppm
FC 5.5 ppm NO CHANGE (I lowered my SWG output very slightly after the test and will see where I end up in a week. I had bumped it up a bit a few weeks back because we were getting a lot of rain)
CC 0 ppm
pH 7.6 (this is amazing! By the end of 2 week my pH is usually at 7.7-7.8. I also started this experiment with a pH of 7.4 and usually lower my pH to 7.2 when I add acid to my pool! Richard, care to comment on this?
TA 120 ppm (I have had the spillover and waterfalls running almost constantly all week for the kids.) NO CHANGE
Adjusted alk 97 ppm NO CHANGE
Calcium 220 ppm NO CHANGE
CYA 70 ppm NO CHANGE
Salt 3600 ppm (readout on AuqaLogic)
Salt 3600 ppm Tayor K-1766)
Pool is still clear and sparkling. My nephew's wife commented on how she didn't need to wash her hair after swimming. She asked what I put in the pool because she said she usually has to shampoo after swimming or her hair dries flat. I told her it was because it was a salt pool. She told me she's been in salt pools before and still needed to shampoo. I just smiled at her;)

So far my pH seems to be more stable than usual. That is what I was hoping for. We shall see if it continues on a regular basis. I guess the real test will be when I need to lower the pH with acid! My grandnephews and grandniece told "Uncle Evan' that my pool didn't make their eyes burn even when they spent most of the day in it ....they liked that! Can't comment on whether that is from the borates or just because I keep on top of the water. I have done nothing to the pool the week they were here except test the chlorine levels Wednesday night because I suspected my 3.5 year old grandnephew went #1 in the pool! There was no CC.

I also tested the spa. The only difference is that my FC was 10.5 ppm. I am not surprised since the kids spent a lot of time in it and the SWG does run when the spa is on. I turned the heater way down since they were spending so much time there. They loved the bubblers and jets! When the spa wasn't running it was in spillover mode so it and the pool were being chlorinated to to same level. I turned off the spillover the last day they were here (thursday) and they were in the spa for several hours with it running so I am not suprised the FC in the spa rose above the normal 6-7 ppm it stays at.

The experiment continues......will report in another week.

Boric acid acts as a pH buffer, but not as much as the carbonate buffer. However, though I have put in the stoichiometric info into my spreadsheet so I can tell you how much boric acid is needed for a certain ppm (and vice versa), I don't have the equilibrium equations put in yet so can't tell you the precise buffering effect. At some point I will and will let you know if that's what's going on.

Your TA of 120 and pH of 7.6 is consistent with relatively stable CO2 outgassing. You might consider lowering the TA to 100 to see if that slows down your pH rise and acid usage even more (if not, then perhaps your pH rise is due to some acidic substance entering your pool -- rain, bathers, etc. -- though I'd like to eliminate the CO2 outgas as a possibility first). Other than that, it sounds like this experiment is an absolutely resounding success! I'll be checking out both the addition of salt (I don't have an SWG yet) and boric acid since both seem to have benefits.

Richard

Quote:

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Originally Posted by chem geek

Boric acid acts as a pH buffer, but not as much as the carbonate buffer. However, though I have put in the stoichiometric info into my spreadsheet so I can tell you how much boric acid is needed for a certain ppm (and vice versa), I don't have the equilibrium equations put in yet so can't tell you the precise buffering effect. At some point I will and will let you know if that's what's going on.
According to the info from Proteam about Supreme 30 ppm is supposed to increase TA 10 ppm. Is this info helpful?


Richard

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Also, wouldn't the buffering effect from borates be immune to the outgassing of CO2?

Yes, the boric acid buffering does not contribute the the outgassing of carbon dioxide. This is very similar to CYA since that also does pH buffering (in addition to its primary role as a chlorine buffer) and also does not contribute to CO2 outgassing.

Gee, you guys really like throwing out numbers to explain, don't ya!:)
OK, here goes. We now know that the ppm number for borates is really a measurement of Boron which has a molecular weight of 10.8117 while the TA is measured as ppm CaCO3 which has a molecular weight of 100.0892 (but remember that CaCO3 is CO3(2-) for alkalinity which counts twice as much as a single charged species such as OH-).

Now the alkalinity from Sodium Borate comes from the following reaction:

B(OH)3 + H2O <--> B(OH)4(-) + H+ pKa is about 9.0

So -log( [B(OH)4(-)] ) + pH + log ( [B(OH)3] ) = 9.0
and at a pH much less than 9, say at 7.5 or so, most borate is in the form of B(OH)3 whereas the alkalinity comes from B(OH)4(-)

30 ppm Borate = 30 mg/l Borate
(30 mg/liter) / ( (1000 mg/g) * 10.8117 g/mole) = 2.775x10^(-3) moles/liter

log( [B(OH)4(-)] ) = pH + log(2.775x10^(-3)) - 9 = -4.06
so [B(OH)4(-)] = 10^(-4.06) moles/liter
technically I should subtract this from the 2.775x10(-3) number and iterate (or solve the equation directly which is what I usually do), but this is an error of only about 4% so I'll ignore it.

So, converting to ppm CaCO3:
(10^(-4.06) moles/liter) * (100.0892 g/mole) * (1000 mg/g) / (2 B/CO3) = 4.4 ppm CaCO3

Unless I did something wrong, it looks to me like they forgot the factor of 2 needed to convert from the alkalinity of single charged B(OH)4(-) to the "twice as much" alkalinity of double charged CO3(2-). Either that or they made a different assumption for pH such as 7.86 which would give me a result of 10. Or they are using an equilibrium constant pKa of 8.64 (that's more likely). As is the usual case, I found a variety of different equilibrium constants from different sources but finally chose the one that I thought was most accurate and also had a temperature dependence that I could derive and put into the spreadsheet.

I had already put the equilibrium equation and constants with temperature dependence into the spreadsheet -- I just didn't hook up all the exact calculations for the different species since that's a pain due to the interations for ionic strength that I have. I'll get to it...

Richard

OK, I finally put in the full Boric Acid equations into my spreadsheet and here's what I found out (assuming I didn't make an error). [EDIT] I initially made a mistake, but have corrected it and corrected the numbers below. [END-EDIT]

One box of 10 Mule Team Borax which you say is 4 pounds and 12 ounces (76 ounces total) and which I've been told is sodium tetraborate decahydrate, will add 9.78 ppm Borate (measured as ppm Boron) so it would take about 5 boxes to get to 50 ppm.

So, to get to 50 ppm in your 6,600 gallon pool, you need 388.6 ounces (24 pounds, 4.6 ounces -- or about 5 boxes plus 8.6 ounces) and 193.9 ounces (1 gallon, 8 cups, 1.9 ounces) of Muriatic Acid or 1.19 quarts per Borax box (you should alternate adding some Borax and then Muriatic Acid back and forth so as not to wildly swing your pH in your pool). This will increase your TA by 7.0 ppm CaCO3 equivalent and will increase your TDS by 416.1 ppm (77.0 from chloride ions from the Muriatic Acid and 339.1 from Sodium and Boric Acid from the Sodium Tetraborate) though some of this TDS increase (about 270 ppm) will not generally be seen in TDS measurements because some of this increase is with the neutral ion B(OH)3 and the standard TDS measurment is made using a conductivity test (which does not measure neutral ions).

It would appear that the rise in TA with Borax is more like a 7:1 ratio of ppm Boron to TA rise, not the 3:1 that Proteam claimed. The 7:1 is also consistent with my earlier calculation, but then I'm the same person doing both calculations so I certainly could have made the same mistake twice!
Perhaps the relatively small increase in TA is why you didn't notice it. It's less than 1 drop on the TA test and you had other things going in your pool in the meantime.

As for the buffering ability of 50 ppm Borate (Boron) in your pool, here's an example. Let's say that we use your numbers and have 2 moles (about 4%) of the total carbonate in your pool outgas as carbon dioxide. This would cause the pH to rise from 7.6 to 7.86 with no Borates in your pool. With 50 ppm Borate, the pH rise is only from 7.6 to 7.71 which is much less. It appears that the Boric Acid / Borate buffer system is quite efficient and is a good compliment to the Carbonate buffer system without having the side effect of outgassing carbon dioxide. [EDIT] Remember that TA is measured in ppm CaCO3 (100.0892 g/mole) while Total Borates are measured in ppm Boron (10.8117 g/mole) and that CaCO3 counts twice for alkalinity (because it can consume two hydrogen ions). So the Total Borates measured in the same units as TA would be 100.0892/10.8117/2 = 4.63 times larger so 50 ppm of Borates has a buffering equivalent closer to 230 which is why it is so effective (it doesn't increase measured TA by that much because most of it is Boric Acid which is uncharged -- this just shows that TA isn't really a measure of buffering capacity unless you use carbonates at a typical pool pH where the HCO3- species dominates). [END-EDIT]

This means that you should be able to run your pool with much lower TA and still get good buffering. For example, you can lower your TA to 80 and without the 50 ppm Borate your pH would rise to 7.97 but with 50 ppm Borate it would only rise to 7.73 so about the same as with the higher TA.

Richard

Quote:

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Originally Posted by chem geek

OK, I finally put in the full Boric Acid equations into my spreadsheet and here's what I found out (assuming I didn't make an error). [EDIT] I initially made a mistake, but have corrected it and corrected the numbers below. [END-EDIT]

One box of 10 Mule Team Borax which you say is 4 pounds and 12 ounces (76 ounces total) and which I've been told is sodium tetraborate decahydrate, will add 9.78 ppm Borate (measured as ppm Boron) so it would take about 5 boxes to get to 50 ppm.
I put in six and it was a bit high. (I thought it might be before I did it) My initial calculations came to about 5 boxes and 2 lbs more (25.75 lbs) but I was not anywhere near as precise as you and based them on Proteams dosing chart and ajusting the weight of the decahydrate as 1.3 more than the pentahydrate needed. I was ballparking the whole way. I also started with an initial borate reading of 15 ppm and my testing is limited by the accuracy of the test strips...not great but it certainly got me in the ballpark pretty easily!
So, to get to 50 ppm in your 6,600 gallon pool, you need 388.6 ounces (24 pounds, 4.6 ounces -- or about 5 boxes plus 8.6 ounces)
Pretty close to what I came up with when I looked at my calculations more closely ! I got about 23-24 lbs!
and 193.9 ounces (1 gallon, 8 cups, 1.9 ounces) of Muriatic Acid or 1.19 quarts per Borax box
In actual practice I used 1 1/4 qts acid per box to keep the pH in line....It's pretty close. I was going for measurements that were easy to do.
(you should alternate adding some Borax and then Muriatic Acid back and forth so as not to wildly swing your pH in your pool).
Which is what Proteam recommends....add 3/4 gal acid and then 10 pounds of the pentahydrate...I added 1/2 gal and 2 boxes at a time....and found that I needed to add more acid... probably would have been right on the money if I added about 2.5 quarts and 2 boxes at a time. I added the acid and put the borax in a 5 gal pail of water and added it to the pool and brushed. It dissolved almost instantly once added to the pool. Pump was running the whole time. If I didn't have a SWG I would have just added the borax to the skimmer but I have found in the past that adding borax or baking soda to the skimmer trips the high salt sensor on my SWG and I have to reset it.
This will increase your TA by 7.0 ppm CaCO3 equivalent and will increase your TDS by 416.1 ppm (77.0 from chloride ions from the Muriatic Acid and 339.1 from Sodium and Boric Acid from the Sodium Tetraborate) though some of this TDS increase (about 270 ppm) will not generally be seen in TDS measurements because some of this increase is with the neutral ion B(OH)3 and the standard TDS measurment is made using a conductivity test (which does not measure neutral ions).

It would appear that the rise in TA with Borax is more like a 7:1 ratio of ppm Boron to TA rise, not the 3:1 that Proteam claimed. The 7:1 is also consistent with my earlier calculation, but then I'm the same person doing both calculations so I certainly could have made the same mistake twice!
Perhaps the relatively small increase in TA is why you didn't notice it. It's less than 1 drop on the TA test and you had other things going in your pool in the meantime.
Right in line with Proteam saying that 30 ppm will cause a 10 ppm increase in TA. Drop based kit might or might not show an increase since the precesion is 10 ppm.
As for the buffering ability of 50 ppm Borate (Boron) in your pool, here's an example. Let's say that we use your numbers and have 2 moles (about 4%) of the total carbonate in your pool outgas as carbon dioxide. This would cause the pH to rise from 7.6 to 7.86 with no Borates in your pool. With 50 ppm Borate, the pH rise is only from 7.6 to 7.71 which is much less. It appears that the Boric Acid / Borate buffer system is quite efficient and is a good compliment to the Carbonate buffer system without having the side effect of outgassing carbon dioxide.

This means that you should be able to run your pool with much lower TA and still get good buffering. For example, you can lower your TA to 80 and without the 50 ppm Borate your pH would rise to 7.97 but with 50 ppm Borate it would only rise to 7.73 so about the same as with the higher TA.

Richard

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I will continue running my pool with the ajusted alkalinity at 97 ppm and see how long the pH remains stable and if I can repeat the results before I lower the ajusted alk to around 80. then I will see how it goes with the lower alk. I intend to post my results weekly. So far I think the addition of borates is a good idea. It certainly is not an expensive experiment when done with 20 mule team. It has only cost me about $35 for the 6 boxes of borax, 2 gallons of acid, and borate test strips!

Now if there was any way to test whether it really has algaestatic properties without my having to turn off the SWG and see how long it takes for my pool to go green :eek:I would do that also!;) Maybe when it gets too cold to swim I will try it. Nothing a few gallons of bleach can't cure!

So far I feel that the experiment has been a success but it is still early into it.
It might be useful to simplify the measurements if anyone else cares to try it.
If I have not made an error 1 box (76 oz) of borax will raise 1000 gallons approx 50 ppm ( slighly higher actually) and will need 5 cups of acid to get the pH back into the proper ballpark. Does this seem like a good way to dose or will it create too large an error on a very large pool? I think the key is to figure out a simple and easy way to meaure the dosage of both the borax and acid. Richard, your thoughts would be appreciated!

Quote:

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Originally Posted by waterbear

If I have not made an error 1 box (76 oz) of borax will raise 1000 gallons approx 50 ppm ( slighly higher actually) and will need 5 cups of acid to get the pH back into the proper ballpark. Does this seem like a good way to dose or will it create too large an error on a very large pool? I think the key is to figure out a simple and easy way to meaure the dosage of both the borax and acid. Richard, your thoughts would be appreciated!

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I get that 1 box (76 oz) of Borax (decahydrate) will raise 1000 gallons by 64.54 ppm which is quite a lot more than the 50 ppm you quoted. I don't think an error of 10% is a huge deal, but this is a bit beyond that (about 15%). This 1 box of Borax also requires 38.56 oz. of acid or 4 cups, 6.56 oz. That's pretty close to 5 cups to be accurate enough.

I'm glad your experiment was a success. The improved buffering alone is a good reason to use borates (boric acid) as fighting a rising pH seems to be the biggest problem most people have. However, it would still be necessary to lower the TA to reduce the acid demand. Though the borates will have the pH rise less, the amount of acid needed to restore pH when it does rise is the same as it would have been without borates.

As for testing the algicidal properties, you could just use a large tub or basin for your test, rather than the entire pool. Of course, the quantities of chemicals you would use would be rather small, but you could also "enhance" the likelihood of developing algae by adding a small amount of nitrates and phosphates to this tub/basin and you could find some algae to dump in as well (if you have any around). That would certainly be a vigorous extreme test! Ideally, you would have two tubs/basins so one would have the borates and the other wouldn't and you'd add the same amount of other stuff to both (and keep both in the sun, keep the water warm, etc.).

Richard

Quote:

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Originally Posted by chem geek

I get that 1 box (76 oz) of Borax (decahydrate) will raise 1000 gallons by 64.54 ppm which is quite a lot more than the 50 ppm you quoted. I don't think an error of 10% is a huge deal, but this is a bit beyond that (about 15%). This 1 box of Borax also requires 38.56 oz. of acid or 4 cups, 6.56 oz. That's pretty close to 5 cups to be accurate enough.
If my math is correct than 3lbs 12 oz should raise 1000 gallons 50 ppm and would need 4cups (1 qt) acid to ajdust the pH.
I

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Does this sound right to you?

Yup, that's right. [EDIT] It's actually 3lbs 11 oz to raise 50 ppm in 1000 gallons and needs 30 ounces (3 cups, 14 ounces) of acid to compensate. Just being anal-retentively accurate! [END-EDIT]

This weeks test results (week 3):
(I have added my nromal amount of water to make up for evaporation each week, btw. I add it after I test...my normal procedure)
Borates 50 ppm
FC 5.5 ppm NO CHANGE (I lowered my SWG output again after the test and will see where I end up in another week. I had already lowered it last week. One of the claims made for tetraborates is less chlorine usage. I thought it was just marketing hype but maybe not....we shall see.)
CC 0 ppm
pH 7.7:eek::D (this is REALLY amazing, last week was 7.6! By the end of 3 week my pH is 8.0 and this is when I usually add my acid to bring it down! I rechecked the pH several times with 3 different kits just to make sure and even used the acid and base demand reagents to make sure the color was where I thought it was! I am going to leave it here and see if it increases anymore in a week.

TA 110 ppm (I have had the spillover and waterfalls running almost constantly last week for the kids and the TA did not move and this is 10 ppm from last weeks test of 120 ppm and that is also the accuracy of the test. As far as I am concerned this is NO CHANGE. I did not bother to repeat this test....close enough for government work, as they say:D
Adjusted alk 87 ppm NO CHANGE (see TA test results)
Calcium 220 ppm NO CHANGE
CYA 70 ppm NO CHANGE
Salt 3700 ppm (readout on AuqaLogic)
Salt 3600 ppm Tayor K-1766)
Pool is still clear and sparkling.
Now this is proof enought for me that the borates have helped to buffer the water. I will continue to report weekly and see what happens. I am particularly interested in my chlorine readings. I have my SWG down to 6% from 15% output in 3 week, normally it's at 10% and maintains about a 4 ppm FC. I raised it to 15% because we got a lot of rain and last week I lowered it back to 10%. Richard, your thoughts on this?

Didn't bother retesting phosphates, I know they are off the scale! (between 2000-3000 ppb).

One thing I have noticed, usually every 3 weeks is when I need to vacumn the pool because stuff collects near the main drain. It didn't need it today. Gonna wait another week and see. Also the skimmer sock usually needs to be changed out every week....this is the second week on the same sock...just took some leaves out of the skimmer. Don't know if this is from the borax or not but it was interesting since I KNOW my pool and what it normally requires. As Alice said, "Curiouser and Curiouser!" (Come to think of it, the pool is so clear it sort of looks like a 'Looking Glass'.;)

Quote:

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Originally Posted by waterbear

TA 110 ppm (I have had the spillover and waterfalls running almost constantly last week for the kids and the TA did not move and this is 10 ppm from last weeks test of 120 ppm and that is also the accuracy of the test. As far as I am concerned this is NO CHANGE. I did not bother to repeat this test....close enough for government work, as they say:D

I have my SWG down to 6% from 15% output in 3 week, normally it's at 10% and maintains about a 4 ppm FC. I raised it to 15% because we got a lot of rain and last week I lowered it back to 10%. Richard, your thoughts on this?

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Evan,

WOW! Maybe the borates will cure cancer! Seriously, I'm very impressed with your results. I (as usual) have a few comments -- take them for what they are worth.

Regarding the TA, though the Boric Acid will buffer the pH, I don't see how it affects changes in TA (carbon dioxide outgassing), at least not directly. It is true that increasing your total borates (ppm Boron) to 50 and adding acid to keep your pH the same at, say, 7.5 actually increases your TA by 6.1 (11.7 at pH 7.8) due to additional relatively small amounts of borate ion dissociated from the boric acid. This increase in the TA is not carbonate, however, and I calculate no change in CO2 outgassing. Besides, with your current numbers, your CO2 outgassing rate is down to 4.0 which is very small so I would expect your TA to be relatively stable.

Now for the chlorine usage question. I don't know why the Boric Acid would cut down the chlorine usage. If you can, try to see if this usage is cut down both day and overnight or if it seems to be mostly a reduction (percentage-wise) in daytime usage. I'm trying to figure out if the Boric Acid is helping to protect the chlorine from sunlight or if it is helping to disinfect and/or oxidize so that chlorine doesn't have to. I don't see the mechanisms for Boric Acid in either process, but it would be good to isolate down to one of these. Since most chlorine usage is due to breakdown from sunlight, it is more likely that the Boric Acid is helping there somehow, but I don't know the mechanism and if it helped prevent breakdown in the same way that CYA does (by binding with chlorine), then that would likely also lower chlorine's effectiveness which wouldn't be good. So we really do need to get to the bottom of this.

Richard

I ran into this little tidbit

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Borates are used to lower the pool's requirement for chlorine, by depriving algae of abundant quantities of dissolved carbon dioxide. The lowering of the carbon dioxide levels will slow algae growth and reduce the chlorine consumption.

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from this webpage and if it is true that algae depend on abundant quantities of dissolved carbon dioxide, then this could explain reduced chlorine usage IF you had algae in your pool using up your chlorine. I suppose that there may always be some algae dropping into your pool, but I didn't think it was that much nor that it ate up that much chlorine (except during a bloom which you then have to shock).

Also, you have to lower your carbonate alkalinity to get this benefit. This would also lower the tendency in the pH to rise (beyond the buffering effect) and would reduce acid demand. Essentially, the borates let you use a non-carbonate pH buffer in your pool so you can run at a lower carbonate level that apparently helps prevent algae and certainly lowers the outgassing of carbon dioxide with its resultant pH rise and acid demand.

So though the website claims that borates reduce the amount of dissolved carbon dioxide in the water, I believe this is only true if you let the carbonate alkalinity get lower which you might "naturally" do by lowering the TA after its rise from adding so much Borax. HOWEVER, as far as dissolved carbon dioxide being reduced, you would have to have your carbonate alkalinity reduced a whole lot more, I would think, since cutting TA in half will only cut the carbonate alkalinity by a little more than half (with water balance turning more corrosive, though probably still in the OK range). It's still an intriguing thought.

[EDIT] After thinking more about it, I don't think the "reduced dissolved carbon dioxide" theory is the answer. Consider ponds and lakes that have algae in them. They are probably closer in balance with the air for dissolved carbon dioxide and that means they have quite a bit less than pool water unless the water is extremely alkaline. It seems to be common wisdom that Boric Acid suppresses algae in pools and that it interrupts photosynthesis in plants (probably does the same to algae, since the kinds of algae found in pools are plants). This WHO document gives more details. Interestingly, smaller amounts of borates (10 ppm) actual stimulated certain kinds of blue-green algae growth, but growth was inhibited at 50 ppm or above with 100 ppm inhibiting more growth (so perhaps this is a more effective level to use??? -- but these tests were done in simulated sea water which is not the same as pool water). [END-EDIT]
Richard

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Originally Posted by chem geek

Now for the chlorine usage question. I don't know why the Boric Acid would cut down the chlorine usage. If you can, try to see if this usage is cut down both day and overnight or if it seems to be mostly a reduction (percentage-wise) in daytime usage. I'm trying to figure out if the Boric Acid is helping to protect the chlorine from sunlight or if it is helping to disinfect and/or oxidize so that chlorine doesn't have to. I don't see the mechanisms for Boric Acid in either process, but it would be good to isolate down to one of these. Since most chlorine usage is due to breakdown from sunlight, it is more likely that the Boric Acid is helping there somehow, but I don't know the mechanism and if it helped prevent breakdown in the same way that CYA does (by binding with chlorine), then that would likely also lower chlorine's effectiveness which wouldn't be good. So we really do need to get to the bottom of this.

Richard

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I will try but I am working two jobs and taking classes so I really only have time to test my water on Fridays. I will see if I can get a chance to do some spot checks in the AM and at night (I don't usualy get home from work until around 1 AM so I don't know if they will do much good). This might have to wait until next summer. I suspect that the known anti fungal action of boron might have something to do with this. Perhaps the boron is killing some of the nasties in the water so the chlorine doesn't have to?

Fine. That's it. I'm dumping enough boric acid in my pool to drop the pH to a normal level and bring the borates up to at least 50ppm. The only questions are where do I get the boric acid, how much do I add and will it hurt my DE filter if I dump it in the skimmer?

Sailork,
It really is much easier (and probably cheaper) to use borax and muriatic acid. They will neutralize each other and produce boric acid/borate buffer in the water and some salt. Just put in 5 cups of acid and pour a box of borax into the skimmer and repeat until you have reached your level. IF you go through this thread you will find where Richard has worked out the dosage for 1000 gal to reach 50 ppm and I gave a close approximation with easier measurements. Don't forget to get some borate test strips....I got mine online from
http://www.diywatertesting.com/aquachek_borate.html
They arrived in about 4 days and it was the cheapest price I could find...free shipping too.

Boric acid is not very soluable, if I remember my chemistry correctly. and you might have a problem geting it to dissovle...and also, if it lowers the pH too much you will need to add borax and that will raise your boron levels even higher.

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Originally Posted by waterbear

Perhaps the boron is killing some of the nasties in the water so the chlorine doesn't have to?

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Yes, but how many nasties are there in water each day? The largest consumption of chlorine by far is the breakdown from sunlight as this generally consumes about half of whatever ppm rate you maintain with your SWG system. So, at 4 ppm this would be 2 ppm lost by breakdown from sunlight.

What we don't know is how much your SWG additionally produces and is consumed by bugs or is used to oxidize organics or ammonia. This could be any amount, but I'm guessing that it is far less than the 2 ppm consumed by sunlight. Generally, the next large consumer of chlorine is ammonia or its biological organic equivalent urea found in sweat (which is mostly water and salt) and urine. Finally, chlorine is consumed by other organics (mostly by nitrogenous organics) from various sources (suntan lotion, material blown into the pool, etc.) but is a rather slow and inefficient process.

Richard

Thanks Evan, I've done some digging around on wikipedia etc and they do mention that boric acid isn't terribly soluble in water. You mentioned that some of the stuff you carry at the pool store contains boric acid. Any idea what they might be doing to get it to dissolve?

These products are meant as weekly or montly additions to replenish the borate level lost by backwashing, splashout, etc. in a pool that already has the required amount of borates in the water. They are used in very small quantities and consist of mostly tetraborates and boric acid or tetraborate and sodium bisulfate (dry acid, pH increaser)
The dosage for the Proteam product (which is sodium tetraborate and sodium bisulfate) is only 4 oz per 10000 gallons at a time!
The NaturalChemistry Salt Water Magic Monthly treatment contains only 1-10% boric acid by weight according to the MSDS for it!

Richard, I've never understood how we can tell how much chlorine is lost through direct action of sunlight and how much is consumed by algae. Given that algae photosythesize I've always assumed they consume most of their chlorine when the sun is shining...

What am I missing? I suppose we could measure CO2 levels during the day and that would give us some kind of guesstimate of photosynthesis?

Ah, thanks Evan. I was thinking something like the methods people use to add CYA would be adequate. I'm pretty sure boric acid is available cheap, but I don't have any idea what might be added to it. Maybe I'll just go to bed and buy a bunch of borax in the morning. :D

Don't forget to get a few jugs of acid and order some borate test strips also!:D

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Originally Posted by sailork

Richard, I've never understood how we can tell how much chlorine is lost through direct action of sunlight and how much is consumed by algae. Given that algae photosythesize I've always assumed they consume most of their chlorine when the sun is shining...

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I am basing my assumption from the experience of users in the algae threads where it appears that algae continue to consume chlorine overnight and that when this stops (which is some time after the water is no longer green and is either cloudy and getting filtered or is near clear), then this means the algae is all killed.

The algae continue to metabolilze (though possibly at a lower rate) at night -- it's just that they oxidize stored organics and "exhale" (so to speak) CO2. During the day, the algae use photosynthesis to build up the organics as "food" and take in CO2 in this process and "exhale" O2.

The oxidation of nitrogenous organics and ammonia also occurs both day and night. So the overnight rate may underestimate the non-sunlight sources of chlorine consumption due to lower chlorine usage from algae algae at night vs. day, but it will at least give one some minimum number to work with.

Richard

Week 4 (1 month milestone)
Been raining heavily for past 2 days and water level in pool and spa both a few inches higher than normal, surprisingly, test results are pretty good! I do notice some effects on my numbers from dilution from the excess water. I collected my samples during a break in the rain this afternoon.
Borates still about 50 ppm....the test strips have division for 30, 50, and 80 and it is much closer to 50 than any other color. I would guestimate that it is just under 50 ppm now. Still within the "good" range and will probably go up when the excess water evaporates.
FC 4.0 ppm (I lowered my SWG output last week after the test and it's also been raining pretty hard the past two days. I really expected the FC to be a bit lower than this after the rains....shame I didn't have time to test it during the week before the rains came.)
CC 0 ppm
TC (oto) looked to be 4 ppm also, more than 3 and not quite 5)
pH 7.7(rechecked this, Used both Ben's kit and Taylor 2005...don't know if it had goneup and the rains brought it down or it's still holding....time will tell)
TA 90 ppm ( I expected this to drop some after the rain...was 110 ppm)
Adjusted alk 70 ppm (CYA also dropped 10 ppm due to dilution from the rain...was 87 ppm)
Calcium 170 ppm (once again dilution from the rain...was 220 ppm)
CYA 60 ppm (rain....was 70 ppm)
Salt 3400 ppm (readout on AuqaLogic)
Salt 3400 ppm Tayor K-1766)
Salt level down once again because of the rain
Pool is still clear and sparkling.

Also tested the spa for chlorine and pH
FC 5 ppm (usually at abut 6-7)
CC 0 ppm
TC (oto) darker than 5 ppm
pH 7.6 (tested this with Ben's kit and Taylor K-2005 also)

I am going to wait for the water level to go down by evaporation before I make any changes to the chemistry. Might have to bump up the TA just a bit by maybe 10 ppm to keep the adjusted alk at aroun 80 ppm. We shall see.
Have also decided NOT to any any acid at this time.
I hope the rains end by Sunday because I need to change the skimmer sock and vacumn. Don't know if the dirt in the pool is from the rains or not....It was pretty clean at the beginning of the week so I suspect that a lot of it is just stuff that washed into the pool.

So far I am very happy that I decided to add the borax to my pool.

Is it possible that the sodium released by the salt cell is being bound by boric acid as it leaves the cell? It seems like that would increase the performance of the SWG by reducing the amount of chlorine that binds back to the free sodium in the water. If the SWG is having to work less, then obviously the pH of the pool will rise less slowly as well.

On the otherhand, maybe it's just been too many years since i took chemistry. :D

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Originally Posted by sailork

Is it possible that the sodium released by the salt cell is being bound by boric acid as it leaves the cell? It seems like that would increase the performance of the SWG by reducing the amount of chlorine that binds back to the free sodium in the water. If the SWG is having to work less, then obviously the pH of the pool will rise less slowly as well.

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Nope, that doesn't make sense chemically. First, sodium is not released by the salt cell. The salt cell doesn't do anything with the sodium ions that are in the water, except that they help the conductivity of the water itself to help carry (balance) charges from one plate to the other. The salt cell simply converts chloride ion into chlorine gas and this chlorine gas dissolves in the water to produce disinfecting chlorine (HOCl). See this post or this post for more technical details.

The main way that Boric Acid (borates) may help reduce chlorine consumption is in inhibiting algae growth. It is well known that Boric Acid will inhibit algae growth (see this link) so with less algae growth, there is less algae for chlorine to kill or deactivate. I am surprised that this results in a measurable decline in chlorine usage since I didn't think the killing of algae in "clean" pools consumed very much chlorine at all, but I could be wrong. I thought that the bulk of the chlorine consumption was from the breakdown from sunlight and I doubt that Boric Acid has anything to do with reducing that process, though if it does (which I believe is unlikely), then I have the concern that it might operate the way that CYA does and bind to the chlorine making a new compound that is essentially ineffective as a sanitizer.

Richard

Doh! I really was forgetting my basic chemistry!

Found this link in some old bookmarks. I haven't used them, am not related, etc., but it is an interesting site that sells bulk chemicals, including borax. You can get a 55 pound bag for $1.35/lb. + shipping. Not sure how this stacks up with 20 mule team on sale, but you won't have all those boxes.

http://www.chemistrystore.com/borax.htm