What's easy to grow for Rocksor, may not be easy to grow for me.
Just like fish, some plants like a certain flow, a certain lineup of dissolved minerals, and very important ....light spectrum.
In both locations I have lived for any length of time, Vallisneria has been easy to grow.
Both places have higher pH, (Milwaukee 7.8, Panama 8.2) and mineral rich (at least 250 ppm Total hardness)
Cryptocorne also worked well, as did some others. As far as light went.....
In Milwaukee, I would scrounge bulbs from a salt water reef aquarist,r he considered spent after 6 months, and would toss, but I found they were great for my plants.
Below Cryptocorne in a Milwaukee tank
Here in Panama i don't use artificial lights at all, only the sun, and I haven't used fertilizers, only supplement are fish wastes.
Val grows great, some others haven't
below, Val in a Milwaukee tank, it grew so well it had to be trimmed
Below a stand of Val, in my Panama tank
I have also found Val likes heavier water current
Below, note how the leaves bend with the current in my former Milwaukee tank (that is also Cryyptocorne in the lower left)
Other species of plants tried, have melted away, from the type water current I use, and my preferred species of fish appreciate.
An Amazon sword I tried had a hard time competing with the Vals, and they forced it into melting.
After a while I planted it in a log to get it closer to light, and away from over competing plants.
I find tannins are sometimes not good for plants, certain blackwater habitats, plants are devoid of aquatic plant species, and only semi aquatic or terrestrial plants survive. When tannins get seasonally inundated with tannins, sonme aquatic plants temporarily melt back, and only semi aquatic grasses like Papyrus thrive.
In the shot above, Papyrus growing above the water surface on the right of the tank.