It's been quite a while (couple of years?) since the size of the 20 Mule Team borax boxes changed from 76 ounces to 65 ounces yet Poolmath has not been revised accordingly. When holding your mouse cursor over the weight of the borax, Poolmath still reports how many 76 ounce boxes are needed. This may confuse new users and should be corrected. If 76 ounce boxes are still available in some markets then maybe a pulldown menu with the box sizes (similar to the chlorine jug size) would be helpful.