Athosanswered grow question 6 years ago The best advice I was given some time ago when I was starting (and most of us ignore for quite a while) is to get a pH pen and a EC/PPM meter. It will take the guessing out of feeding the plants. Believe me, it really helps, you forget about how many ml to feed, it is a matter of how much PPM you feed. You don't need a profesional EC/PPM meter, a cheap pen meter will do.