Just thought I'd share my experience with everyone in case it is helpful. I'm about to start with Borax for two reasons.

First, I've never been able to keep my ph down without adding acid all the time. Higher borates have helped others control this so I'm hopeful this will get it under control.

Second, I've been battling mustard algae for about 1 1/2 years now, and I'm hopeful this will help that as well.

Here are my numbers going in for my inground pool about 23k gallons:

FC 5
CC 0
pH 7.5
Alk 90
Cal 220
CYA 45

Any helpful advice as I proceed is welcome. I plan to start adding Borax and Acid tomorrow. Hopefully sharing this will be helpful to others who have similar problems (assuming this helps me )

Jim