Quote 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!
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