Hi, about an hour ago i went to go check on my planted 20gal and i eventually found my Dwarf Gourami floating, I got to touch him and he flipped his fin and sprayed me. He then goes to the bottom kinda life less but exerting an amount of energy some times and then he just layed on the ground lifeless. I tapped on the glass and nothing. I tested the water and did a water change while all of this was happening just to make sure nothing was bad. Everything was normal. I noticed my drop checkers were blue. I have my DIY Co2 going directly into the intake of my cansiter filter and the drop checkers are normally green. So what I was wondering if after the DIY CO2 is finished could it possibley produce a toxic gas and would get sucked directly into the tank and kill my fish? Sounds like a long shot but I just dont know what killed him. All the other fish are fine. And just to be sure I uncapped my Co2 and am going to redo it soon. Any help?:huh: