Light is the standard LED that came with the Roma 125 (technical info on this light is proving frustrating to find!). Timer set for 5 hrs (it has a 'sunrise' and 'sunset' period).
Sf has it right
🙂
The stock lighting is wickedly weak for this tank dimensions
(You can pretty much count on Fluval to showcase their tanks with just added plants for the photoshoot & you won't find any aquascape "growth over time" videos, though they did produce some nice "setting up the aquascape" videos
😉)
From Fluval website:
Aquarium dimensions: W80 X D35 X H50CM
Light: 10W LED LIGHT
Look at the LED placement - does is cover the length of the tank equally?
Can you count the # of LED?
I suspect the supplied lighting is built to general spec rather than particular LED etc components which is why it's difficult to find detailed information - emailing Fluval tech support with any specific serial numbers may elucidate some detail
Given the water column height (50 cm), look for higher watt (individual) LED as well as overall increased wattage on any additional LED lighting you add (HOT5 would likely come in significantly cheaper)
As you're not wanting to add CO2, you want to balance light intense enough to reach the substrate with available nutrients (including CO2 - heavily stocked fish can do a decent job of this but then I suspect the filter may be "underpowered" in that respect (unlike the Spec series which has massive filter area for tank size))
Use shorter periods of more intense lighting - Sf again
😀
You could try one of the "liquid CO2" products - add small amounts daily just like your fertilizer
Weekly water change of 50% will help keep system balanced
If you have a Soda Steam system, you can also carbonize some tap water & add this daily for CO2
😉