The Great Tetraborate Experiment!

[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.

[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?

[waterbear]

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!

[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...

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?

[sailork]

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.

[waterbear]

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

[chem geek]

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...

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

[waterbear]

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.

[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.

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