Hi Lala,
my (little) experience in a similar situation.
I started one year ago my (very first) tank, SG 1.002, sand only, and artificial roots. I just wanted a little corner of plants, since they actually didn't fit that environment (a mangrove river bank). Also, I wanted it looooow-tech. So, no CO2, and my standard 2x 39W, 6500 K, T5 tubes.
1) After quite some time of research I opted for Ceratophyllum, which seemed hardy enough, and didn't need any nutrient from the substrate (that solved the problem with the very poor substrate I had): I simply attached it to a hollow rock; this way, I also solved the rotting problem typical of this plant, if buried in the substrate. I started with freshwater, and very slowly rose to SG 1.002; it did grow quite well, but always looked miserable, and covered with some kind of algae: worth mentioning here that the tank was not mature at all. I was adding simply a liquid fert, once a week, half the recommended dosis.
2) In July I removed what was left of the hornwort, and tried Vallisneria Asiatica. In this case I had to enrich the ground a bit, so I used Tetra Plant Crypto tablets, and again a liquid fertilizer, on an irregular basis. Again, the plants are struggling, with the leaves opened wide, instead of growing nicely vertically. Also, lots of rotting tips. They are propagating, though, and I can see that the plants born in there appear faring better.
Again, I'm a beginner, so I AM doing lots of wrong things in there, but I must admit so far my experience with plants is not a happy one. But I keep trying. And learning, hopefully.