Tell him to buy "Washing soda" if he can't find borax. But, be careful. Washing soda will raise the pH more than borax. So he should be adding 2 boxes of washing soda or 4 boxes of borax via the skimmer, waiting 30 minutes to an hour; testing and then repeating if he sees no change in pH. Once he sees the SLIGHTEST increase in pH, he needs to drop back to 1 box of washing soda or 2 boxes of borax . . . OR he will overshoot and end up with high pH.