I picked up a 10 gallon tank from a garage sale the other day and was thinking about starting a planted tank on my desk at work. My office has a big bay window that faces south so it receives direct sunlight between the hours of 1pm - sundown and ambient natural light at all hours of the day. My goal here is to create a no-light, no filter, no supplement planted tank. I haven't seen any of these in my quick search online but I'm fairly certain it can be done. All nutrients for plants I'd like to be provided by the nitrate cycle/substrate in-tank with fish, and I WILL be doing water changes (10-20% weekly?). I was planning on setting up some low light requirement plants in here, as well as a Betta (since there wont be a filter on the tank, any idea if a non Betta will be able to survive with the oxygen put into the water via photosynthesis?) and some ghost shrimp. A relatively low livestock list at least, but I haven't finalized it yet. I plan on using some good substrate and focus primarily on the plantscape rather than the livestock. Any planted tank guru's see anything wrong with this experiment or see anything i'm overlooking? Also, anyone able to comment on the oxygen/co2 cycle for a planted tank with livestock? Thanks!