水草情迷

i bought some Ammania gracilis two week ago.
its colour used to be a very bright red .
But their colour have faded away now...
only top new leaves remain red and others become greenish.

i use 3x20watt FL plus 2x27watt PL with a 60cm tank(it looks quite dangerous after i squeezed the PL onto the top of the tank)
the substrate is ada black soil
ph about 5-6
kh about 1-2
temp. about 24C'
using TMG as trace(once a week) and KNO3 (little per day)as Macro (i also put some iron tablets(Tetra cypt) in the substrate)
DIY CO2 (3 bottles !!!!! however the yield is low due to the low temperature)
Totally 10 fish
Help!!!!!

可能係光唔夠，你個缸有幾高呀？

the distance from the lamp to the substrate is about 30 cm

據我所知, 紅柳在硬水內會生長得較好呀.

My god ....
if i change the kh
i am afraid all my Cryptocorynes will all melt again....
now i know why i can't see people keeping Crypts!!!!