Just a few more words on bacteria. The main purpose of the bacteria is to convert the excretion (ammonia etc) of the fish into plant's food (nitrate). To remove the nitrate, plant is used. These nitrate and nitrite converting bacteria is very sensitive to Chlorine. So it is better to use rain water. If tap water is used, make sure they are left for a while before introduction of fish. If you have a friend who has a running fish tank, get some gravels from she/him will help a lot.