Nutrient deficiency of this plant

The plant at the back...



Notice the new leaves are yellow while the old ones are green.... And its not flat..

I'm not sure what deficiency this plant has...

I have 72w T5HO in a 20 gallon, and I have pressure co2 and I dose flourish comp with some other ferts.

 

What type of plant is it? What are the "other ferts"?

 

What type of plant is it? What are the "other ferts"?

It is a stem plant I believe. The leaves are red underneath...

I have flourish comp, iron, trace... I'm aware that I'm lacking the three NKP bottles and I'm planning to buy them soon...

 

Dovah Can you help us identify this plant please?
Edit: I don't think she's on right now but she will probably be on later because it's pretty late and Hong Kong and the US are in different time zones.

 

I say this a lot but it looks like Hygrophila to me. I know there are some plants that will turn red when they receive enough light, Bacopa caroliniana being one that I know of for sure (it's green in my 150, turning red in my 125.) I'd guess that your plant was in a shaded area of the tank but now it's taller/receiving more light. That's my guess as to what's happening anyway.

 

Alternanthera ReineckiI looks very similar; it has green leaves with purple underneath. I grow it with 1.75 w/g (CO2, macro and micro).
72w of T5HO over a 20 gallon tank is a huge amount of light (3.6w/g). Look into dry NPK. Especially P

 

So its in the process of turning red? but what about the older leaves, will they turn red too?

It closely resembles "Alternathera ReineckiI roseafolia".
aniroc Its my first time hearing a dry fert. I've only known liquid ferts like seachem flourish products. I'll look into it...