this might have been covered earlier in the thread - and it's just my opinion - but since you spent so much effort getting the apistos, why risk them with any additives like CO2 or fertilizers?
I know you are only allowed a couple of tanks and you love plants as much/more than fish, but if I had expensive fish then I wouldn't be adding anything to the tanks that wasn't really needed... but then again I'm quite risk averse :lol: