Originally Posted by EmilyN
You really can't cycle a 3/5 gallon tank so don't worry about that.
I have to disagree with this - my 5 gallon is fully cycled. :) Any tank with a filter 5+ gallons is going to cycle whether you want it to or not, unless you constantly change the filter media and scrub the heck out of the gravel, and let's face it, why would you?
What cycling is: the process of building up nitrifying bacteria in the filter (in other places too, but mostly the filter) that converts your evil ammonia into less evil nitrates.
What happens during a cycle: first, a source of ammonia is added to the water. Either you can do it with pure ammonia, fish food or a dead shrimp, or it will happen anyway when your fish poos. The ammonia will build up and nitrites will appear to eat all the ammonia. The nitrites will build up, then nitrAtes will appear to eat all the nitrites. Then all you have left are the nitrates. You do a water change, and your tank is cycled.
Fishlessly cycling a tank is, of course, easier on the fish, and requires less work because you only have to test the water. With a fish-in cycle, you have to do lots of water changes to keep it safe for the fish (spikes of ammonia, nitrites and nitrates are bad for fish), and each water change delays the process, so it does take a lot longer.
That's cycling in a nutshell. Let me know if you want to know more. :)
As far as live plants go, as long as you have a light on your tank you should be able to grow hornwort, wisteria, elodea (also called anacharis) and lacefern. With or without, you should also be fine with java fern, java moss and anubias. All of these are super-basic plants that really don't need anything special from you. They'll live off your fish poo and that's it. Faster growing ones (the first four I mentioned) will speed the cycle up, because they suck up waste.
With a cycled tank, properly stocked, a 25-50% water change once a week is enough. If you do a 100% change in a cycled tank, you might kill off some of the beneficial bacteria. In an uncycled tank, one 50% change AND one 100% change a week is necessary, to get all the bad gunk out that might contribute to ammonia levels.
Mugs don't need to be new - they just need to be clean. :) Sake cups can be a lovely, stylish alternative. :)