i have used canna and vitalink in the past. Last grow was done with the vitalink easy for veg, its a one bottle solution for hydro. They are all pretty much the same to be honest. good luck
i left the water 24 hours to reduce the chlorine, then Ph's it and added a small amount of nutes to leech the system. I tend to use 3 to 4 times the container size, so a 20 litre pot would be flushed witrh 60 litres :)
I have read that other factors affect the overall strength. exposure to low temps during flowering stunts growth yet has been reported to increase potency/
Correct harvest time and harvest procedure, basically if you harvest too early or too late it affects the overall quality, as does fast...