It is a good idea to go organic with PH buffers, it works out quite cheap aswell. I worked with commercial chemical buffers in the past and have had a few finger print removing accidents, This Blog will cover how to make an safe and organic PH buffer and how to automate the delivery of it.
Building the Auger delivery system:
Automated Green House Blog:4 - Building an automated feeder
Paulo's Guise to making the Egg shell Powder:
Eggshell Powder - Aquaponics Lab
Paulo also loves his 3D printing and is a big fan of opensource, so there may be a open source 3D printed version available soon!
Like I mentioned in the video, there will be a upcoming Blog post on a automated self learning control system for PH management [just need to find a PH probe for cheap].
So Keep watching for updates and let me know what else you would like to see, the main home page is:
Automated Green House Blog's Home Page
Mike