Equipment for a 1 gallon shrimp bowl? Java Moss = filtration + food!
I have four 1 gallon rectangular shrimp jars with no light or filtration, they're just sitting in a window where they're exposed to morning sun. The temperature there is not consistent, so they're sitting on a reptile heating pad, and one of them has a heater with a thermostat to balance out the temperature a bit. With just a submersible heater on the side I was getting warm water at the top with cold water below, but the heater underneath seems to have helped counter that and I suppose add a tiny bit of circulation now. I'd also thought about burying a submersible heater in glass marbles which I'd replace a substrate with, so it would be out of sight but would still have water circulation, and then using just plants such as moss and Java Ferns which don't require a substrate.
I'd added the floating plant Azolla which has covered the top now, so surface biofilm isn't really a problem anymore. And I threw in a Nerite snail to keep the container's surface clean, despite that they're competing with the shrimp now, as the direct sunlight was nevertheless resulting in some algae.