hello;well don't be discouraged by this....I personally don't like this concept(bottom watering) beyond the stage of plant sturdiness then I switch to top watering (clear water flushes/fertilizer applications:~15% of total applications flowing through the cell/or small pot (but don't let it puddle) to reduce soluble salt build-up...Container cell size /volume is helpful to help manage media moisture.... Fertilizer concentrations /frequencies are determined by media and container volume;growing in less than optimal greenhouse conditions (i.e.light quality and duration);plant type and stage of development;root-zone temperatures;and so forth....
With regards to Impatiens, you might sneak a glimpse at the Ball Flora Plant Site(cultural info-left margin)
http://www.ballfloraplant.com/Site_Map.aspx
some useful theory can be found on the ncsu and u-mass floriculture sites...