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I've got a high-tech tank with green and red plants, and I'm using Seachem root tabs and Thrive all-in-one from Niloc-G. The plants seem happy and are growing well. However, I've noticed that the new growth on my red plants is coming in green (picture #1), and the Rotala rotundifolia I added a week ago has doubled in size, but it's all green (picture #2).

I'm wondering if I need to make any adjustments to get the red coloration back. Should I add iron supplements to complement the Thrive? Or maybe increase the lighting?

Some tank specifics:
46g bowfront, CO2 is on and the dropper is middle green (no yellow), Fluval 3.0 light at 75% brightness for 6 hours a day (mainly to control the hair algae). I'm dosing Thrive 5 sprays 2x a week, doing 33% water changes weekly, and my water parameters are all good. pH is around 7.6-7.8.

For reference, the Thrive chemical composition is:
Total Nitrogen(N) 3.09%
Lumiailable Phosphate(P2O5) 1.58%
Soluble Potash(K2O) 10.4%
Magnesium(Mg) 0.32%
Calcium(Ca) 0.03%
Sulphur (S) 0.76%
Boron(B) 0.008%
Copper(Cu) 0.0002%
Iron(Fe) 0.65%
Manganese(Mn) 0.168%
Molybdenum(Mo) 0.0006%
Zinc(Zn) 0.0038%

I'd appreciate any advice on how to get the red coloration back on my plants.

I'm no expert, but I was under the impression that iron supplements are a must for red plants to maintain their color. Without it, some may not just lose their vibrancy but actually decline in health or turn green.

When it comes to growing red plants that are naturally green, lighting is key. The red coloration is essentially the plant's defense mechanism against intense light, a stress response to protect itself. Think of it like this - the more light you add, the more nutrients you'll need to provide, so if you're planning to increase lighting intensity, make sure to balance your CO2 and fertilizers accordingly.

Echoflux wrote: ↑Thu Jan 20, 2022 11:58 am When it comes to growing red plants that are naturally green, lighting is key. The red coloration is essentially the plant's defense mechanism against intense light, a stress response to protect itself. Think of it like this - the more light you add, the more nutrients you'll need to provide, so if you're planning to increase lighting intensity, make sure to balance your CO2 and fertilizers accordingly.

I'm considering tweaking my lighting setup to try and get that red color back. Should I bump up the Fluval 3.0 to a higher brightness level, assuming I can manage the algae, or keep it at 75% and just run it for a longer period each day?

Echoflux wrote: ↑Thu Jan 20, 2022 11:58 am When it comes to growing red plants that are naturally green, lighting is key. The red coloration is essentially the plant's defense mechanism against intense light, a stress response to protect itself. Think of it like this - the more light you add, the more nutrients you'll need to provide, so if you're planning to increase lighting intensity, make sure to balance your CO2 and fertilizers accordingly.

It's about finding that sweet spot between the two.

Thrive has sufficient iron for plant pigmentation, covering both red and green plants. Adding more iron might actually cause more harm. The notion that red plants require a lot of iron to maintain their color is a common misconception. What really helps is high PAR lighting with a strong red and blue spectrum. Unfortunately, the Fluval 3.0 doesn't quite fit the bill. Don't get me wrong, it's still a solid light fixture - I've used it before and plants grew well, but the red ones just weren't as vibrant. Nitrate limitation can also play a role in getting red plants to display their color.