thanx for the advise Mr Pink !!! im running a 1000w hps on these. its just i got 2 opposite responses , one to lower ppm (too much fert) and one to increase ( more fert)so i guess its 50/50. here. stick around and well see how these cubes work !!! but ive heard theyre flawless and basically no work. i just need to find out what ppm is max or common for this type of grow. ive never done drain to waste before this. gh nute calc for drain to waste is 850-900 max and the same recipe for recirculating is 1400. just want to know where i should expect to be with DRAIN TO WASTE ppm strength. keep it comin guys i need all input and info......who agrees.......... we should raise ppm .........or lower ppm and raise N