comments:
It's not necessarily hard but small tanks are fragile tanks: What would be a very minor change in say a 10 or 20 gallon tank will have an outsized impact in a 3 or 5 gallon tank because the water volume isn't large enough to smooth out the variables. As an example I have a one of these 6 gallon cubes next to my bed with shrimp and snails. For a desktop setup you could go with a 3 gallon version but I wouldn't go much smaller than that if it's your first tank.To keep it stable I don't do water changes and only top off 1-2 times a week with distilled water when about a pint of water has evaporated out (I have a little clip on the side with marks to tell me when I've lost enough water to top off) - that's about ±2% on the water level. I feed sparingly maybe once every other week as a treat, and once a month I put literally 3 drops of fertilizer in the water if I remember to. (I've probably skipped more months than I've remembered and the plants are still growing fine.) One big caveat: You must HEAVILY plant a filterless tank - like way the hell more plants than you think you need, everywhere, like crazy!Those plants ARE your filter. I've got three golfball-sized clumps of Java Moss (Taxiphyllum barbieri) tied to the hardscape, some random Anubias I grabbed when I was picking up the tank, a couple of low-growing plants that I think are some kind of Chlorophytum/spider plant, and about 1/3 to 1/4 of the surface covered in Duckweed that I snagged from a local pond and quarantined in an old Chinese food soup container for a month to make sure it wasn't bringing anything I didn't want along for the ride.That's probably the minimum planting for a 6 gallon tank. (I know a lot of folks hate duckweed because it grows like crazy and is hard to get rid of, I like it because when it grows past about 1/3 of the tank surface I scoop some out to knock it back to about 1/4 and it takes all the excess nitrates, minerals, etc. from the fertilizer / shrimp food / waste with it. Occasionally I'll steam some of it and mash it into a ball to drop in the tank for the shrimp to eat instead of a "regular" feeding, they seem to like that and the snails go wild for it.) If you've never done a filterless tank before I would put a basic sponge filter in there. Doesn't have to be big - I have this one (Aquaneat "Medium") in my 6 gallon, the small version would realistically work in either of the tanks I linked above (the filter works better if you cut it up and put an actual airstone at the end of the hose, but you don't have to).Sponge filters use bubbles from an air hose / air stone to lift water in a tube, and that pulls water in from the aquarium through the sponge where bacteria can form colonies. It's a very low flow rate but it'll do a decent amount of mechanical filtration at start-up and with shrimp you really don't have to clean it for a very long time (like months) - the shrimp and assorted microfauna in your tank will graze most of the biofilm & detritus off the surface of the media and keep it from clogging up. You should pull the sponge off and wring it out in a bucket of clean water occasionally to keep it effective as a mechanical filter. If you don't ever clean the sponge eventually it becomes functionally a filterless tank with an airstone in it: The filter sponge is full of mulm and bacteria and maybe there's a little water circulation through it from the bubbles and uplift but it's nowhere near what it started at and mainly it's just the airstone making bubbles and circulating water in the tank. If you don't go for the sponge filter you probably still want an airstone in your tank to promote water circulation. "No Tech" tanks that don't even have that are IMHO way harder to run successfully (especially in small volumes!) because the water can stagnate and the dissolved oxygen level can drop dangerously low. You'll recognize this by the water smelling foul/funky as the anaerobic bacteria take over.