Weedhound - The gravity is some weird stuff. I think that it does make the plants denser which is nice. However - you know how it says move the lights up six - 12 inches? Well - make sure you actually do move them up a bit. For some reason, after I added the gravity, my top leaves turned very purple and became very photosensitive - which caused light burn - which I believe results from some sort of nutrient build up in the leaves. You will see what I mean. Also - it made my rez a little gunky but not too bad. I am going to try it again on my next grow for the whole 12 days that it recommends. I only ran it for about 4 days b/c the plants were ready to be flushed so I didnt really give it a fair trial.
P.S.
When I used it, I cut down my nutes by 1/3. This stuff didnt make my EC go up at all, which was weird. My theory is that the Gravity does not make the EC reading go up b/c it is not a salt. When you pour it in, it looks more like a lipid - you see an oil on water effect. This is def. some weird shit. Correct me if my EC theory is wrong. Peace