I would replace the small bottle between your liter bottle and the tank with a check valve. You may want to use a 2L beverage bottle with 1 cup sugar, 1/4 tsp wine yeast, 1 tsp baking soda, 1 tsp soy flour or protien supplement. It should go at least 3 weeks. Fill with water 3/4 full. If you have chlorine in your water, add so dechlorinator.
Air stones will work but you will have to clean them often. I use a Hagan ladder.
Andrew, MASI Treasurer
This message is always under construction: 75-gallon tank; 2, Eheim 2026 filters - one twice broken; Tek Light with 4, 54W T5s (6000K) ; Sand on top of 4:1 sand:clay mixture; Milwaukee CO2 controller; PlantGuild vortex CO2 reactor; pH = 6.6, kH=70mg/l, GH=120mg/l; EI; Flourish excel on 50% weekly water change: AGA Member.