rockm

All of this discussion on pH is really just pie in the sky for the most part. Most plants, with the exception of 'Lime haters" like azalea, camelia, stewartia and a few others, can survive in the pH range found in typical bonsai soil. It's rarely a substantial problem if you keep up with repotting--unchanged soil can become too acidic over a period of years, depending on where you are.

Acid lovers like blueberries and the like can have more organic material added to their soil mix to compensate.

I don't measure pH in my soil. Others do. I find it's too much work for not enough return. It can also lead to alot of misguided futzing with the soil that's really counterproductive. I also suspect that your R.O. may be at the root of your problem. Tap water is usually adequate for a limited collection of bonsai, unless you get your water from a local well.

As for a good source of BC refinement in Calif., you're not in the best place for them. You might contact the local bonsai club to see if anyone has been growing a specimen or two and ask for assistance. You might even ask if you could help with care of someone else's established BC. This can give you hands-on experience in repotting and pruning, etc. I've had people ask me to help repot and style mine. Believe me, I welcomed it, especially with the bigger trees.