Your setup is more high tech than any of my setups, but I do have dirted tanks. I will say that your dwarf sag is going to go crazy. Mine, without as much light in a 90g and no co2 formed a lawn-like carpet fast. With all those ferts and exploding new dirtbed, you have so many options. Mermaid weed grows feathery and is all of the colours you want to add, yellow and red. Same as rotala magenta, although I find it grows more solidly pinkish red.
For red plants, and pardon me for not knowing the actual name, my personal favorite is ludwigia rubin 'mini'. It grows easily super red, underside of leaves and all, with smaller, more delicate leaves than regular ludwigia rubin, and faster, I find.
There is also ludwigia arcuata, which has spikier leaves more resembling rotala, but it's easy to grow and also grows super red.
Myriophyllum tuberculatum is labelled red, but grows more of an orangy red, for diversity in colour.
I think later you might want to try a more difficult foreground plant, like pogostemon helferi, it is more interesting, but grows slower than dwarf sag producing lateral shoots to form a carpet. I think this plant in smaller sections would look amazing.
I am sure there will many other suggestions. I think your options are endless.
Btw, how did you separate the dirt from the sandy path?
For red plants, and pardon me for not knowing the actual name, my personal favorite is ludwigia rubin 'mini'. It grows easily super red, underside of leaves and all, with smaller, more delicate leaves than regular ludwigia rubin, and faster, I find.
There is also ludwigia arcuata, which has spikier leaves more resembling rotala, but it's easy to grow and also grows super red.
Myriophyllum tuberculatum is labelled red, but grows more of an orangy red, for diversity in colour.
I think later you might want to try a more difficult foreground plant, like pogostemon helferi, it is more interesting, but grows slower than dwarf sag producing lateral shoots to form a carpet. I think this plant in smaller sections would look amazing.
I am sure there will many other suggestions. I think your options are endless.
Btw, how did you separate the dirt from the sandy path?