I don't see a problem with a simple set up. All those fancy gadgets that people buy are not 100% necessary. They just make maintenance easier. A local pet store had a 10 gallon tank with only an undergravel filter, housing mushroom and xenias. The tank was up and running for over 12 years, never crashed. However they did do frequent water changes to the tank. The equipment we buy is to keep the water quality high without having to change the water on a daily basis. One thing that people should take into account is bioload, and how tolerant the animals you house are to nutrients. Tanks housing some critters do not need to be as "filtered" as others. As for tap water, some cities have much higher quality water than others, I personally would use RO.