New beekeeper here in Northern California. Got my first nuc in April. The colony has been growing nicely and looks healthy. The bottom frames were nearly completely full so I added the Flow super last week. Yesterday, looking in the side windows, they had started to build a tiny section of comb on one of the visible frames and I was super excited. Today there is a ton of condensation in the frames, as seen through both side windows and the back. The bottom pest tray is also wet (in just the section closest to the front of the hive). It has not rained here recently. I tasted the wetness and it doesn’t taste like anything, not sweet or sticky, just seems like water. I am worried something is wrong or this will encourage mold growth. Anyone have any thoughts on why it is so wet in there, and what I can do to make it better? Or is this OK? Thank you!!
Condensation in supers often happens when there is a strong nectar flow. As the bees fan their wings to dehydrate the honey they are making from the nectar, the water condenses on the cooler surfaces inside the hive. It is not harmful, and you don’t need to do anything.
One other thought. You are in Norcal. I imagine most beekeepers in your area use double deep brood boxes. Are you doing that? They will probably need 2 deeps worth of food to help them get through the winter, unless you want to feed them aggressively in the colder months. 
Thank you so much for your response.
Yes, I am in NorCal near San Jose. My mentor says he uses single deeps on the majority of his ~40 hives near me. But I’ll check with him to see if that means he is feeding them during winter.
Thanks again!