I'm in league with technorancer on this one.
Lots of people fertilize Neps (and other CP's for that matter), and the plants appear to appreciate orchid/epiphytic fertilizer. It seems like, for Nepenthes, it is best to stick with foliar feeding. That method is preferred by many for several reasons, namely: it minimizes potential root damage, and it does not "contaminate" the pot/soil.
I have noticed that *watering* my plants with Superthrive really causes the algae in the pot to take off -that's why I stick to foliar feeding.
Superthrive can be mixed with fertilizers -I, too, heard that one should not let the treated water sit for ~24 hours. When I add Superthrive to water and let the water sit, I notice that the water changes color after a while, dunno if that means anything or not.
Flip Side, it sounds as if you are always watering your Neps with Superthrive. You may want to stick to a less constant schedule of Superthrivin'. Once a month or so is how often I Superthrive/fertilize plants, and that is not even every plant -just a few that I am worried about, those that have been repotted, or those that are new additions to my growing environment. Using this schedule, I find that the plants are happy and I have few problems with algae and unwanted guests.
-trev