The Great Tetraborate Experiment!

[waterbear]

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

Does this sound right to you?

[chem geek]

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]

[waterbear]

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 (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
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'.

[chem geek]

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

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?

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

[chem geek]

I ran into this little tidbit

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.

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

[waterbear]

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 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?

[sailork]

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?

[waterbear]

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.

[chem geek]

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

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

[sailork]

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?