What is the main points of planting Tonina and Eriocaulon ?

Hello, i come from Hong Kong. My english isn't good, but i try my best to talk/discuss with you.

My Little Tank's information:
45x30x30 (cm) , about 35 (L)
two T5 8w (765)
External Filters
It is Non co2 Tank
ADA soild (the black one)
average temperature is 27degrees(using the fan to cool down)
fertilizer : Tropica Plant Nutrition 3ml /week, Seachem Excel 5ml /day

fish: 10 tetras , one dwarf cichlid (some fish and shrimp i don't know their names)
plants: Tonina , Eriocaulon , Microsorium , Cryptocoryne ......


Last time when i try to plant Tonina sp. "belem" ,after a week its leafs(always not the top of the plants) began to be brown. And than it kept turning brown until it died. And while i was trying it, i was using ADA Brightly Light and seachem excel .But now, i have already change my fertilizer.

some photos about it.


What is the reason?
I like Tonina very much, please help me.
And also, i like Eriocaulon too.
So i want to know the main points of planting them.
Thank you.

 

Oh, why do they want co2 gas more than excel?
thank you

 

But i can't add co2 gas because it is expensive to me.(i'm a student)
How can i decrease the co2 running away from my tank?
are duckweeds work?
Thank you

 

Okay, let me try the DIY co2 system.
I think i can try to make it if it can help me to keep tonina.
If i stop adding excel now, will they die?
My friend had found a species which can be planted at none co2 tank. That is Tonina sp. "uatumg".
And also, i found Tonina fluviatilis can be planted at none co2 tank.
When they grew very tall and i cut them, after that they all died.
But my friend is success! So i want to try this species next time.
Thank you for you comment.