Quote Originally Posted by waterbear View Post
Also, the addition of borates will tend to move pH down and can (and does)help with rising pH in most pools and reduces acid demand (Chem geek disagrees and says that total acid use will stay the same but I have seen a reduction in acid use in my pool and in customers pools). The algaestatic effects of borates have been demonstrated to me sufficient times for me to recommend them as a useful pool additive and one that is really beneficial in pool with a SWG, where the reduced chlorine demand can translate into better pH stability because of less on time of the salt cell.
My comments on the borates having no effect on total acid used, just on the rate of pH rise (so acid is added less frequently, but more needs to be added to move the pH) are based on borate buffering that does not outgas carbon dioxide. However, if waterbear sees a real effect of acid reduction, then it is always possible that the borates affect the rate of carbon dioxide outgassing, perhaps related to their lowering of surface tension in the water or some other effect inhibiting the facilitated transport near the water's surface. In my own pool I haven't seen the total acid change, but my pool is covered most of the time so that only some of the pool's pH rise is due to carbon dioxide outgassing. We'll need to track more users to see the effects. I know that there are some who have added borates and not seen benefits in their pools with regard to acid addition and in some cases even in the rate of pH rise (which doesn't make sense).

Richard