[@marko@]

my advice:
-dose excel
-get the airstone out of there and use a proper diffuser (like the hagen bubble ladder), actually you could just use the hagen CO2 package and get a bottle and more importantly, CO2 resistant tubing.
-get a canister filter, they dont outgas CO2 like HOB and other wet-dry filters do.


thats really your only problem, too little CO2 for so much light. you dont need pressurized, just more CO2 getting diffused and less outgas. i had the hagen system on my 10 gallon, and it pumped so much CO2 my riccia pearled higher then in my pressurized 20L where i didnt dare turn the CO2 so high up (of course i the added some surface agitation to outgas the extra and got it to good levels).