Hello guys , i have 3 types of plant in my aquarium and it has passed 1 month since i bought them and they aren't growing . They are really healthy, but I see no change at the plant and its the same size like it was 1 month ago . I have tetra substrate like gravel and i also use fertilizer every month. If this is a lack of CO2 how can i fix this ( without going at the pet store to buy co2 pump , tablets etc...) ? Thnx 
