When adding borax and acid for a secondary buffer and algaestat I usually split it into tow or three equal doses. You really don't have to wait after each addition (I add borax first and then acid) but I do brush down the sides of the pool to "stir" everything after each borax/acid addition. Of course, I do this with the pump running. Let it circulate for about 24-48 hours before readjusting pH or testing your borate levels. It's really pretty much a no brainer if you have calculated the proper amount of borax and acid. If you overdose by a bit it's not a problem at all but generally you want to shoot for 50 ppm for a chlorine or bromine sanitized pool or spa. With biguanide up to 80 ppm will give better protection against pink slime and white water mold.