okay so I bought some GH ph down because my tap comes out at about 7.1. I was told all it will take is a few drops to bring it down to about 6.5. im growing in soil. I have a liguid test kit and a digital meter. the thing I want to know is to be able to get my ph down to 6.5 im having to add 30 drops. is that okay? its a big difference from a few drops.