Plant nutriment requirements vary from plant to plant. There's really a huge amount of different nutrient mixes out there, but what you need to do is research.
a. What macro/micro nutes does my plant like, what pH do they like?
b. Which NPK nutrient solution can work best for my plants needs, you don't NEED to substitute micronutes, but your plants could develop a little less healthily
I have a bio seaweed concentrate nutrient mix, weak on Nitrogen, stronger on Phospohorus and K(Potassium), with 10% organic matter (which I assume has non NPK macro/micronutes) which I use on lettuce. My hydro lettuce are thriving, my earth lettuce also love it as a foliar spray.
But anyway, research your plants!
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Worm tea works wonders. Runoff from an aquarium seems to do the trick.
If you're looking for something a little more grocery-store, try adding two tablespoons of miracle gro, and one tablespoon of epsom salt per gallon of water in the system.
Best of luck!
A standard plant fertilizer should be good - theres lot of hydroponics instructibles on here.