Borax (borates) in DE filtered pool

What is floc, clarifier, stabilizer, cyanuric acid,
algaecide, brightener, dichlor, sodium hypo,
sodium bisulfate, ....??
IkeRay
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Borax (borates) in DE filtered pool

Postby IkeRay » Sat 27 Oct, 2007 00:52

i just got done reading this article and it seemed that he had a salt water filter/generator, but i liked his results and the "silker" feel of the water described. i understand that i would lose a bunch of borates when i backwash the DE filter (once a week) but how much would i really be losing?

also, he had a 6600 gallon pool (quite small) in comparison with my 30k gallon pool. it took 5 boxes of 4lbs 20 mule team borax, (20 lbs) and thus i would have to use ~100 lbs worth (or ~25 boxes) to achieve the 50 ppm initial borate reading. is it worth spending the $100 one time use and then $5/week to keep boric acid up (would that even be enough)? im not having problems with pH or anything else really (other than algae), i want the water texture results more than the chemical results.

finally, 5 cups per 1 box right, so that would be ~7 3/4 gal acid (maybe closer to 8 gal acid)?


so that would make total cost $100 (borax) + $125 (HCl)[might be cheaper, i dont remember it being anywhere near $50/case at the pool store, ill check again, it might be closer to $20/case so $40 which helps a lot in cost :)] + $10 (test kit)= ~$250 after taxes [or $~150 if HCl is cheaper than what im finding online right now]? again i ask...is it worth it?


chem geek
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Borax (borates) in DE pool

Postby chem geek » Sat 27 Oct, 2007 02:57

Just FYI, The Pool Forum website you referred to has many of its people, including waterbear who did the Borates experiment, now over at TroubleFreePool.

Your pool is larger than most so yes in 30,000 gallons it would take 110 pounds (23-1/4 boxes since each box is 76 ounces) of 20 Mule Team Borax and 842 fluid ounces (105 cups or 6.6 gallons) of Muriatic Acid (31.45% Hydrochloric Acid). By the way, one box of 20 Mule Team Borax is 76 ounces weight and is about 9 cups in volume (Borax isn't very dense -- it's roughly the same density as water).

As far as how much you would lose each week from backwashing the DE filter, I don't think it would be very much in percentage terms. You basically have one box of Borax for every 1290 gallons of water and I doubt you backwash anywhere near that amount.

As for the feel of the water, adding salt to the pool also changes its feel and some people like that as well, though most people have to get to 1000-1500 ppm to notice the difference. The water is also easier on the eyes.

As for whether adding the Borates is worth it, that's a personal choice. It will act as an algaecide so should help out there, though really you can keep away algae using chlorine alone, but need to maintain an absolute minimum Free Chlorine (FC) level of at least 7.5% of the Cyanuric Acid (CYA) level.

Richard
IkeRay
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Borax (borates) in DE pool

Postby IkeRay » Sat 27 Oct, 2007 10:45

chem geek wrote:Just FYI, The Pool Forum website you referred to has many of its people, including waterbear who did the Borates experiment.

Your pool is larger than most so yes in 30,000 gallons it would take 110 pounds (23-1/4 boxes since each box is 76 ounces) of 20 Mule Team Borax and 842 fluid ounces (105 cups or 6.6 gallons) of Muriatic Acid (31.45% Hydrochloric Acid). By the way, one box of 20 Mule Team Borax is 76 ounces weight and is about 9 cups in volume (Borax isn't very dense -- it's roughly the same density as water).

As far as how much you would lose each week from backwashing the DE filter, I don't think it would be very much in percentage terms. You basically have one box of Borax for every 1290 gallons of water and I doubt you backwash anywhere near that amount.

As for the feel of the water, adding salt to the pool also changes its feel and some people like that as well, though most people have to get to 1000-1500 ppm to notice the difference. The water is also easier on the eyes.

As for whether adding the Borates is worth it, that's a personal choice. It will act as an algaecide so should help out there, though really you can keep away algae using chlorine alone, but need to maintain an absolute minimum Free Chlorine (FC) level of at least 7.5% of the Cyanuric Acid (CYA) level.

Richard



curious...what kind of salt are you referring to? just plain old, every day NaCl (table salt/sodium chloride) or something else. 1000 ppm you say...that would be quite a significant amount of salt to add. can you elaborate....you are just so helpful!


also, i just went and checked prices (not online, in person) and the borax at wally world is $2.67/box (24 boxes is ~$65) and HCl (muriatic acid) is $4/gal at the pool supply store ($16/case x 2 cases=$32). so in order to create the boriatic(?) environment, it wouldnt cost much more than $100 which sounds much better than my first prediction of $250.
chem geek
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Borax (borates) in DE pool

Postby chem geek » Sat 27 Oct, 2007 13:59

IkeRay wrote:curious...what kind of salt are you referring to? just plain old, every day NaCl (table salt/sodium chloride) or something else. 1000 ppm you say...that would be quite a significant amount of salt to add. can you elaborate....you are just so helpful!


also, i just went and checked prices (not online, in person) and the borax at wally world is $2.67/box (24 boxes is ~$65) and HCl (muriatic acid) is $4/gal at the pool supply store ($16/case x 2 cases=$32). so in order to create the boriatic(?) environment, it wouldnt cost much more than $100 which sounds much better than my first prediction of $250.

Yes, the salt is plain sodium chloride salt, but it needs to be quite pure. It's the same salt that is added to pools to convert them to salt pools for saltwater chlorine generators (SWG). See this thread for brands of solar or pool salt you can use.

I still can't help you with regard to whether it will be worth it for YOU to spend $100 and have 50 ppm Borates in your pool. It's a personal decision. I don't know anyone who has done it that regretted it, BUT do keep in mind that if you have a dog that drinks from the pool every day that the borates are near the "first symptoms" limit at about a pint to quart per day for a medium-sized dog. The risk is low, but is higher than those with dogs that drink from the pool might want.

Richard
IkeRay
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Borax (borates) in DE pool

Postby IkeRay » Sat 27 Oct, 2007 15:55

chem geek wrote:Yes, the salt is plain sodium chloride salt, but it needs to be quite pure. It's the same salt that is added to pools to convert them to salt pools for saltwater chlorine generators (SWG).

I still can't help you with regard to whether it will be worth it for YOU to spend $100 and have 50 ppm Borates in your pool. It's a personal decision. I don't know anyone who has done it that regretted it, BUT do keep in mind that if you have a dog that drinks from the pool every day that the borates are near the "first symptoms" limit at about a pint to quart per day for a medium-sized dog. The risk is low, but is higher than those with dogs that drink from the pool might want.

Richard



thanks for the direction. im not worried about dogs drinking my pool water, the only dog that ever drank it moved out when my sister-in-law moved out, so we are a pet free home currently. i will remember that though if we do get a dog in the future, not let it drink too much or any pool water.

how much salt would i need to add? one website said 10 bags (55lbs each bag, so 550 lbs) per 10000 gal of water, which comes out to 30 bags for me, while another said i would have to get up to 3200 ppm (or 1 tsp/gal), and according to my stoichiometry...

6 tsp/oz*16 oz/lb=96 tsp/lb*1gal/tsp=96gal/lb*40 lbs/bag=3840 gal/bag
30000 gal(pool size)*1 bag/3840 gal=~7.8 bags

...that would mean, to achieve the 1000-1500 ppm you suggested, i would only need 1 tsp/2gal, which makes it only 4 bags (3.9 bags, or 156 lbs).

does it require more salt to get to the desired dilution or am i missing something here?

also, i hope im not bothering you too much :)
chem geek
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Borax (borates) in DE pool

Postby chem geek » Sat 27 Oct, 2007 16:15

First of all, your pool already has salt in it so you should measure that with a salt test (the Aquachek test strip is good for this or you can use the Taylor K-1771). To add 1000 ppm salt to 30,000 gallons would require 250 pounds of salt. So the actual needed amount for your pool would likely be less since it starts out with more salt already.

The website that said 10 bags of 55 pounds, so 550 pounds, per 10,000 gallons of water is wrong. That would add 6600 ppm of salt. The real number is that 100 pounds of salt in 10,000 gallons raises the salt level by 1200 ppm.

In my own pool, I just use chlorinating liquid, and over time the salt level builds up if I don't dilute the water. That's because I have a cartridge filter so there is no backwashing and it's oversized so I only have to clean it once a year. So there is very little dilution of my pool water. Bleach and chlorinating liquid add about 0.8 ppm of extra salt for every 1 ppm Free Chlorine (FC). All sources of chlorine convert 1 ppm FC to 0.8 ppm salt, but I'm talking about an extra 0.8 ppm on top of that. So bleach or chlorinating liquid end up adding 1.6 ppm salt for every 1 ppm FC after the chlorine gets used up.

Richard

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