Is Borax hard to find?

[waterbear]

Some history on Sodium Percarbonate and swimming pool:

Sodium Percarbonate WAS sold to the commercial pool industry by one company that I know of as a non chlorine oxidizer. It was discovered that it not only was not compatible with chlorine but it also messed up ORP readings that many commercial pool installations depend on to maintain properly sanitized water. (I was actually told this by the President of said company.) Said company had stopped selling it for pool use several years back and (after moving their manufacturing location across the country) now is selling phosphate removers!

There is still one company selling sodium percarbonate for pool use as a specialty product to clear a badly fouled pool. The company is Proteam (who brought us Supreme and did much of the initial research on Borax as an algaestat in their St. Augustine, FL test pools before they were bought out by Haviland.)
The product is called System Support and it actually does work but is expensive (both for the product itself and for the large amount of dry acid needed to maintain the pH, since sodium percarbonate, as chem geek said, is highly alkaline). Waste has called it the "Alka-Seltzer Treatment" which is an apt name.

I personally have used it on green swamps with all kinds of leaves and stuff at the bottom. It causes the stuff to float up so it can be easily skimmed off and can usually clear a mess like that in about 48 hours with one treatment. Since it is being used in a pool without any chlorine at the time and since the peroxide is expended there is no problem getting the chlorine to hold after the treatment in my experiences with it. IMHO, it is useful for a pool service that cannot be on hand to dump chlorine in every few hours to clear a pool and where expense is not an issue.

However, as Ben said, once you have a pool with chlorine in it (and not a nasty green swamp) there is NO valid reason to put it in a pool.