yes they can be used in hydro, if you dont use them your buds will be the size of a pencil eraser, follow the ff nutrient feeding schedule avalible on there web site
I use both of these products also for flowering and my last grow was my largest when using these products, but i also used there soluble nutes in conjunction w/ their liquid nutes OpenSesame, BeastieBloomz and ChaChing helps to get massive yeilds