2021 Spring/Summer OD Hydro Autoflowers

This week I moved the system outside on the patio. I use a transfer pump to reduce the weight by pumping nutrient out of the kit so it is easier to move. The nutrient is then pumped back into the reservoir. This week I started misting foliage with a light solution 5ml/L of BioCanna Rhizotonic. It seems that the beneficial bacteria drive PH up to 7. I am not sure how to stabilize PH around 6. I tried to use Botanicare Power PH down product but even 60ml of that into 12 gallon of nutrient solution only brought it down a few points and I have a feeling it will creep back up in a day or two. Update May 15th: I cycled the tank and buffered the tank with 1ml/5gal of Ph Down from Nutri+ after all nutrient was added. It is a Phosphorus based acid at 35%. PH is sitting steady at 6.2. I also added BioCanna Rhizotonic at 50ml/10L. As I forgot to add this in as a root shooting starter last week.