Citric acid and fulvic acid are safe. Phosphuric acid is not (this ones in all the liquid ph bottles)
Discussion
Hey guys. I just got some feedback from a brain surgeon/ chemist doctor friend of mine. I was asking about the liquid Ph booster drops. He does not recommend using the drops I use because of the potassium hydroxide. He recommends using good old fashion Arm n Hammer baking soda. I’ll have to play around with it to see what amount to use to get to a neutral Ph of 7. 
Some of us true organic growers know whats toxic!