I watch my PH and when it gets to 8.0 I dose the recipe 1 on BRS two part and it goes back up to 8.05 to 8.1. i keep my alk around 8 dkh. it does not take much to do this. I add it slowly. I have 1200 gal so I add 600 ml's and it does the trick and I do this every 4 days or so.
do you add ro water strait to your system? that could also have an affect since it is low ph