1) For smaller tanks (up to 10 gallons), you should run the tank for 2-4 weeks before adding fish. This will give the beneficial bacteria time to colonize the filter and substrate and help to establish the nitrogen cycle.
2) For larger tanks (over 10 gallons), you can usually get away with running the tank for 1-2 weeks before adding fish. However, it's still best to err on the side of caution and wait a bit longer if possible.
Here are a few tips for cycling your tank:
- Use a water conditioner to remove chlorine and chloramines from the tap water.
- Add a source of beneficial bacteria to the tank, such as a commercial product or a piece of filter media from an established aquarium.
- Keep the tank temperature at a constant 78 degrees Fahrenheit.
- Feed the fish lightly during the cycling process.
- Test the water regularly for ammonia, nitrite, and nitrate. The goal is to have 0 ppm ammonia and 0 ppm nitrite, and less than 40 ppm nitrate.
Once the water parameters are stable for at least a week, you can add fish to the tank. Start by adding a few hardy fish, such as guppies or platies. Wait a few days to a week before adding more fish.