Cycle the aquarium before you stock it.

What cycling means

A new aquarium needs time for beneficial microorganisms to establish on filter media and other wet surfaces. These organisms process toxic ammonia into nitrite and then nitrate. The process is often called the nitrogen cycle, and it is why a new tank should not be stocked heavily on day one.

Set up the biological foundation

1. Install the filter and ensure the tank has continuous circulation and oxygenation.
2. Add the substrate, hardscape, and plants you plan to keep.
3. Use a water conditioner appropriate for your source water.
4. Add an intentional ammonia source according to the product instructions.
5. Test ammonia, nitrite, and nitrate regularly and record the results.

How to read the tests

Early in the process, ammonia may rise. As the first bacterial population grows, nitrite may appear. A mature cycle is indicated by the aquarium processing its ammonia source with no detectable ammonia or nitrite and measurable nitrate, interpreted alongside your test method and water-change routine.

Test kits vary, so follow the instructions carefully and compare results over time. If your results are confusing, bring a water sample or clear photos of the test colors to the PetZoneSD / Hakkai team.

Plants help, but they do not replace testing

Fast-growing plants can take up nitrogen compounds and make a new aquarium more forgiving, while rooted plants and biofilm add useful surface area. Plants do not guarantee that an aquarium can safely support livestock. Keep testing and stock gradually.

Stock slowly

Once the aquarium is processing its ammonia source consistently, add livestock in small groups and observe the system between additions. Avoid combining a new biological load with major changes to light, CO₂, fertilizer, and water chemistry.

For source-water planning, read the San Diego aquarium water guide. For shrimp, pay extra attention to stability and mineral availability with the shrimp aquascape guide.

Common cycling mistakes

• Replacing all filter media at once and removing established biology.
• Rinsing filter media in untreated tap water.
• Adding too many animals before the cycle is established.
• Stopping tests because the water looks clear.
• Changing several variables at once, making the result impossible to interpret.

Keep the cycle healthy

Maintain steady flow, avoid overfeeding, preserve useful filter media, and make consistent partial water changes. A planted aquarium becomes easier to manage when its biological foundation is treated as part of the aquascape—not an invisible afterthought.