Your First 30 Days With a New Aquarium: Week-by-Week Guide
The first month with a new aquarium sets the foundation for everything that follows. Rush it and you will fight problems for months. Follow a structured approach and you will enjoy a thriving, low-maintenance tank. This first 30 days new aquarium guide from Gensou Aquascaping at 5 Everton Park gives you a clear week-by-week plan.
Day 1: Setup
Place your tank on a level, sturdy surface away from direct sunlight and air-conditioning vents. Add substrate — 3–5 cm for planted tanks. Arrange hardscape (rocks and driftwood). Fill halfway with water poured over a plate to avoid disturbing the substrate. Plant your aquatic plants. Fill the rest of the way. Install and start the filter, heater and light. Dose water conditioner (Seachem Prime) to neutralise chloramine. Add a bacterial starter culture. Set your light timer for 6 hours daily during the first month.
Days 2–7: The Waiting Begins
Your tank will look beautiful but is biologically empty. The nitrogen cycle has not started yet. If using aqua soil, ammonia will begin leaching within 24–48 hours — this is normal and beneficial. If using inert substrate, add a pinch of fish food daily or dose pure ammonia to 2–4 ppm to feed the developing bacteria. Test ammonia every other day. Expect the water to cloud slightly around day 3–5 — this bacterial bloom clears on its own. Do not add fish. Dose liquid fertiliser if you have plants.
Week 2: Ammonia Phase
Ammonia should be detectable and may rise to 2–4 ppm. This is the fuel for the first stage of bacteria growth. Continue testing every two to three days. You may notice a slight algae bloom on the glass or hardscape — this is normal in new tanks. Gently scrape it off during your first small water change of 20 per cent at the end of week 2. Keep lights at 6 hours to limit algae while plants establish. Add more bacterial starter if you want to speed things up.
Week 3: Nitrite Phase
Ammonia should be dropping, and nitrite will appear for the first time. This is a positive sign — the first group of bacteria is working. Nitrite may spike to purple on test kits; this is normal. Continue testing. If nitrite exceeds 5 ppm, do a 30 per cent water change to prevent it from inhibiting bacterial growth. Plants may show signs of adjusting — some melting or yellowing of older leaves is expected. Do not panic; new growth will follow. Perform another 20 per cent water change at the end of the week.
Week 4: Almost There
By the end of week 4, ammonia should be at or near zero. Nitrite should be dropping rapidly. Nitrate will appear — this means the full cycle is establishing. Test every two days. When ammonia and nitrite both read zero on two consecutive tests 48 hours apart, your tank is cycled. Perform a 50 per cent water change to reset nutrient levels before adding fish.
Day 28–30: First Fish
Choose hardy species for your first additions: ember tetras, Corydoras, cherry shrimp or endlers are excellent choices. Add no more than five to six small fish. Acclimate them using the drip method over 30–60 minutes. Feed sparingly — once daily, a tiny amount. Test ammonia and nitrite daily for the next week. The bacterial colony needs to adjust to the new bioload. If either parameter rises above 0.25 ppm, do a 25 per cent water change.
Common First-Month Problems
Cloudy water: Bacterial bloom — it clears in 3–7 days. Do not add chemicals; just wait. Brown algae on glass: Diatoms — completely normal in new tanks. Wipe off gently; they disappear after 4–6 weeks. Plant melting: Transition shock from the shop to your tank. Leave them alone; new growth adapted to your conditions will emerge. Green algae on glass: Reduce light hours to 5–6. It usually resolves as plants grow in and outcompete the algae for nutrients.
What NOT to Do in the First Month
Do not add too many fish at once. Do not change the filter media. Do not chase pH — let it stabilise naturally. Do not add algae-killing chemicals — they treat symptoms, not causes. Do not skip water changes. Do not give up — every thriving aquarium went through an awkward first month. Patience during these 30 days pays dividends for years to come.
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Still Have Questions About Your Tank?
Drop by Gensou Aquascaping — most walk-in questions get answered in under 10 minutes by someone who has set up hundreds of tanks.
5 Everton Park #01-34B, Singapore 080005 · Open daily 11am – 8pm
