My discus are with their fins closed all the time and some of them are no
coming out they are always hiding, I just got them 4 days ago, but before
that I had 2 nice snakeskin in the same tank but thay died because an
overdose of CO2, thanks to my Yeast DIY CO2 system

DIY CO2 is not recommended with discus.

In fact, I'd recommend a pH controller for a planted tank that will be CO2
injected. Most fish don't need that fine a control over pH, but discus are so
darned delicate.

I know, there are people who keep discus in injected tanks without pH
controller. But they are generally pretty experienced -- with both discus and
planted tanks.

IMVHO, keeping discus in CO2-injected tanks is not for beginners.
Discus-keeping and plant-keeping are both pretty challenging on their own;
combined, it's a steep learning curve. And discus are so expensive.


Leigh

http://www.fortunecity.com/lavender/halloween/881/