Fresh squeezed lemon juice- easy and organic. Don't use the bottled stuff, it has other preservative chemicals in it and is also weaker than fresh juice.
Takes a bit of time to disolve and read right on a ph meter and I wouldn't use to much as it really increases the PPM and will cause salt induced nute lockout in some cases
Thanks... learned something today... the bottled lemon juice has been working for me... but I'll try vinegar next time... I think that bottled lemon juice attracted drain flies to my babies
Im using phosphoric acid apprently its inorganic so plants can absorb it
which I think is a bad thing but I brought it from a hydro store and its for hydro so im not sure