I've been experimenting with an all unmalted grain recipe for the last couple of months. Have been using enzymes for saccharification, namely alpha amylase and glucoamylase. I have also been using RO water and adding minerals to build my own water profile. The results have been great, however the final pH is really low at pH 3.3 and the wash is taking a very long time to reach final gravity.
I think I need to add a buffer / stabilizer so that the pH doesn't crash so much. I know beer guys use Five Star 5.2 stabilizer, however I have heard that it add 100ppm of sodium, which an effect taste.
Are there any other commercially available solution? Any suggestions?
Baking soda has been working well for us for correcting pH. Last time we had pH issues, I added an ounce per barrel, measured, and repeated until we got back up to 3.8. Flavor was fine. I don't know that I would use it proactively, though.
If you are using RO and building up your mineral profile from scratch, why not just correct it there? You need more alkalinity. Calcium carbonate (chalk) or sodium bicarbonate (baking soda) or both. It's likely whatever you are adding is simply resulting in too low a concentration.
Salts don't make it though distillation. What concerns brewers here is irrelevant to us.
Baking soda is cheap and easy, you can add it proactively. In the quantities you might use to manage pH crash - it would make a beer very salty. Chalk won't completely dissolve unless your water is high in co2, but don't worry about it, as fermentation will take care of it.
What type of grain are you using? Also I went on Brewersfriend website and used one of their water profile calculators. I used a standard one. I'm also on RO water and use baking soda, calcium carbonate, and gypsum it has worked very well for me. The calculator will help you figure out how much you need for your particular set up.