My substrates bubble like crazy the first 8 weeks after setup.hey guys,
i'm a little worried that my substrate has gone bad! the fish and plants seem fine, but whenever the substrate is disturbed it is quite bubbly! NO2, NH3, and PH are all normal. this is my Walstad 20g and has been up and running for about a year. hmmmmmm
Your tank, though, is a year old. If the bubbling is mainly in areas where plants aren't growing, then this is a "horse of a different color". It sounds like organic matter has accumulated and your substrate has developed anaerobic pockets. This is not good for your fish, plants, and the tank ecosystem.
Poking the substrate is a good short-term solution. For the long-term, you may have to add bigger plants, increase water circulation to those problem areas, or increase lighting (to encourage better plant growth). Hard to say what the exact solution is, but it sounds like you'll figure it out.