To touch on the heavy metal thing.
http://oda.state.or.us/dbs/heavy_metal/detail.lasso?-op=eq&product_id=10286
They don't have zinc listed.
Of the heavy metals listed, there is a whopping 1.39ppm of metals in the bottle. Then this is cut down by adding less than 1ml of it per gallon of clean water. At that concentration, you're using all of 0.000368ppm of metals. We're talking about 0.000000037% of the final solution being a heavy metal.
Considering what is contained in your tap water, or in that sushi you ate, or that sweet 1900's Balder cap... You are TRIPPING saying that the metals are what is adding weight to the plants. The amount of metal provided to the plants for uptake isn't even a millionth of a gram. Entertaining this thought is ridiculous.
Before going for the hardcore method of keeping plants shorter with Bushmaster I'm using sea kelp extract this time around. I'll probably give Bushmaster a shot in a grow or two depending on how well this works so I can compare both methods. You know, so I can be educated by experience rather than talking out of the wrong end.
I have run Gravity for the last few grows, stuff works exactly as advertised. For me, I get flowers stacking on flowers. I usually use it in my reservoir for 2 feedings at about 0.5ml/gallon or less. I drop my EC about 30% but I don't move the lights. Burning has happened before but has not happened in other grows. Depends more on the strain and pheno how it will react in my experience. Definitely invigorates and stimulates flowering forcing the plant to throw out tighter nugs.
I am also going to be using Snow Storm. For me, it is all about having top grade medical herb. The difference maker can be quantity of Cannabinoids on the plant. More resin, more high, less used. So if I can take my resin production up say 10% to 20% with a $10 bottle of stuff (given good reviews and everything else they make working as advertised) then I'm all for it. If not... then it is no sweat off my back and I can let other people know how the product works based on my experiences.