Is it possible to switch over to T5 from the T8?
That will give you better PAR as T5 design tends to higher intensity even at similar wattage, most T5 will appear brighter
As you have the ADA light, try again but begin with 30min, after a couple days extend to 45 min etc - with slow growing plants, this needs to be a slower process than if a mix of fast and slow plants
In order to establish new (tastier) plants, add some elodea etc for fish to snack on, try floating plants such as Limnobium laevigatum (sorry not clear on the common name as it seems to vary rather a lot) as the roots should distract the gf
“Duck weed” the tiny single leaf floating plant that is an aquarium scourge - unless you have gf
(I suspect a gf forum has loads more ideas)
It’s often not that easy/fast to establish Vallisneria from “bunch” plants - instead invest in some aquarium nursery pots such as Tropica’s Vallisneria range (these are ones I happen to be familiar with), note that some Vallis species are slower, more difficult than others
If you’ve a gravel only substrate, I’d open some of Tropica’s Nutrition Capsules and add to the Vallisneria planting zone
Algae crew - with gf I’d add a few larger snails such as “mystery” snails (the blues are really lovely), also zebra Nerites (look for larger specimens) (I find the “onion” and “tiretrack” Nerites to be overly generous with their egg laying - white spot decor everywhere
)
I believe you’re adding CO2 so I’d try adding Bolbitis - check with Aquarium Gardens etc for when a larger shipment arrives from Tropica - this will give you more “instant” plant and it’s a much faster grower than Anubias species
Crinum calamistratum Is also not very palatable (but expensive for a larger specimen)
You might also enquire after the XL pot range - some of the swords might manage gf depredations if plant is big enough etc to start
Any root plants, I’d add the additional nutritional support to the gravel