I would grow just one under that light, especially since it is your first time doing it.
For nutrients, you can use any number of nutrient lines, but if you are in the market, why not go with the Flower Power nutrients that ILGM sells?
I personally use the General Hydroponics 3-part system (FloraMicro, FloraGrow, FloraBloom). I also augment that with General Hydroponics CaliMagic (calcium/magnesium sup) because my tap water is only ~70ppm (that’s a measure of how many mineral solids are already in the water) and General Hydroponics Armor Si (silica supplement - I don’t really know why I do this, just that other people highly recommend it).
Whatever system you use, you want to make sure that you are adequately covering your plant’s needs. To further help with that, informing us on all the aspects of your growiing environment would help. These are things to consider for hydro:
- What kind of hydro system (deep water culture, recycling, ebb and flow, autopot, etc)
- How big are your buckets?
- How are you putting air into your bucket and how much air?
- How big is your growing area?
Hydro growing is a great way to grow IMHO. I particularly like that you can immediately address issues you see with your plants and generally don’t have to wait long to see the results of changes/fixes.
The 300w MarsHydro is a very popular light around here and I am sure you will get some better informed answers re: growing with it.