No, you do not need substrate ferts for those plants, water column fertilizing will be fine. You will, however, need CO2 for them to thrive. And, definitely do lose the actinics.Now, my plan is to grow a glosso mat, with some hairgrass in a iwagumi style set-up.
My question is this: Do I need fertilizer placed under the colourquartz (inert) in order to achieve what I want?
What types of fertilizer is suggested for under the substrate? Where can I find it?
BTW, I would not start out the tank with those plants. Plant lots of fast growing stems, then once tank stabilizes, make your desired arrangements with the plants you want.