not really, i would automatically think water !!!!
not enuff or too much, stick ya finger in the soil and determine which one it is
as for the super thrive
you can use this thru out the whole grow with no problems at all ,its more of a personal preference really
ganja plants love superthrive and there is a noticable difrence in the size and quality of the buds when finished ,compared to a ganja plant with out it.
do a quick search on it mobay has had some quite brilliant results when using superthrive
hope this helps elway m8
cheers all