I use a product from GH (general hydro) called "Sub Culture". It is made by GH and can be used in both hydro and soil. This is my first grow in years and am only in 3rd wk veg so cant really tell difference but GH recommends with each res change. So far everything is great so something working.... until I dropped my fan today on one of my prized plants "smash" dammit!!!!!!!!! Oh well the fan is fixed and she is tapped up and alive for now.... Its always something!!!!!!!!!!!!
BTW i am growing in 4x4x4 rockwool cubes, in pots filled w/ hydroton, top fed......