....have 2x 2ltr bottle at 1/2 tsp yeast and 2 cups sugar, and change one bottle each week? so basically one bottle is going to operate for 2 weeks....
Yes, that's exactly the process I use in my 20 gallon tank, along with a Limewood diffuser. I'm very happy with the results I'm getting. It's not a perfect system by any means. I do get a gradual drop in CO2 in the last few days of the week before replenishing a bottle. But it's good enough for me. This is my first live planted tank... and to be honest, if my plants grew any faster, I wouldn't be able to keep up with pruning and trimming!
I would go pressurized. No more pain mixing your stock every week ......
I actually enjoy mixing the CO2 bottles every week. It's fun!
55g: Finnex Planted+ & MonsterRay, Pressurized CO2 w/ Atomic inline diffuser, Eheim 2217, Eco-Complete, EI ferts. Lemon, Glowlight, and Black Neon Tetras; Harlequin Rasboras; Otos; 1 Red Wag Platy; Nerite Snails. Staurogyne repens, Hygrophila corymbosa, Ludwigia repens, Ludwigia glandulosa, Red Melon Sword, Wisteria, Golden Lloydiella, Water Sprite.