So for now i have in plan to buy real co2 bottle and system but in 4-5 months. So i want to know from these bio/disposable co2 systems what is the best and what you would choose: 1. Dennerle co2 bio 120-http://dennerle.com/en/products/aquarium/co2-fertilization/bio-co2/co2-plant-fertilizer-set-bio-120 This system comes with gell with tablet stabilizatores etc. they tell that for 30 days you will have constant amount of co2, after you empty the bottle they give you their recipe to make your own new diy mix and you put it in that bottle and keep using or you can buy new bottle. (i would get two bottles at start so i can start using new after one is empty) 2. Tetra optimat co2 - Tetra CO<sub>2</sub> Optimat Simple kit, disposable can - hose - bell/diffuser. So once a day you need to press can and fill that bell inside of aquarium with co2 and that's it, it works by some kind of diffusion where co2 is in contact with water and its being consumed by water at some rate. New bottle is around 8$ and you need new every 1-1.5 months. 3. Jbl proflora bio 80 or 160 JBL ProFlora Bio160 So practically diy system with nicer bottles and system, you get ingredients A and B (they didnt say anywhere but it's sugar and yeast) mix them in that bottle, after max 24h you get fermentation process and you have co2. After i spend two bags of ingredients that i get with this i could probably make my own mixture with firstly writing down how much of ingredients A and B did they put in those small bags. So those are my options now i want some of these that will be mostly stable i dont want co2 levels go up and down all the time because that's like vip invitation for algae So any one of you did try some systems or similar to those? Any suggestions? Any other system like this that i didn't see? And yes my tank is 22gallon with alot of plants and at this moment i am using liquid carbon and probably with any of those systems i would keep using liquid form too but in half of dosage.