Aptus is very expensive but based from my friends using it and their results, hands down one of the best boosters with minimal effect on ppm readingsI just harvested tops from my cheese plants in budding. Will harvest bottoms in a week or so when they plump up a lil and finish heres my set up. I used to grow hydro but this is my first soil grow. Started over with all new grow stuff this time. I'm in Michigan so I'm legal to grow 12 so that's what I worked my way up to do. I used to just do 4 hydro plants at a time under 1000w old school hps magnetic ballast and air cooled hood. Now I'm rocking all leds. Loving the new set up so far.