Aquarium Cycling FAQ: 12 Beginner Questions Answered
Cycling a new tank means growing a colony of nitrifying bacteria that converts toxic ammonia first to nitrite, then to nitrate. The process takes three to six weeks for an unseeded tank and uses ammonia from a bottle or fish food as the bacterial food source. This aquarium cycling faq consolidates the most common questions our customers at Gensou Aquascaping at 5 Everton Park ask before stocking their first fish, and this guide answers the 11 questions Singapore aquarists ask most about cycling.
How long does cycling take in Singapore?
An unseeded fishless cycle typically completes in 21 to 35 days at Singapore’s 28-30°C ambient. Warmth speeds nitrifier replication, so local cycles run faster than temperate-climate guides suggest. Tanks seeded with mature filter media from an existing system can cycle in 7 to 14 days. Track ammonia and nitrite daily — the cycle is finished when both drop to 0 ppm within 24 hours of dosing 2 ppm ammonia.
What is the nitrogen cycle in plain language?
Fish waste, leftover food and decaying plants release ammonia. Nitrosomonas bacteria convert ammonia to nitrite. Nitrobacter and Nitrospira then convert nitrite to nitrate. Nitrate is far less toxic and is exported through water changes or plant uptake. Without an established colony, ammonia accumulates and burns gills within days. Healthy filter media is where 95 per cent of these bacteria live, not the gravel or water.
Should I cycle with fish or without?
Fishless cycling is the humane standard. You add bottled ammonia or pure household ammonia to 2-4 ppm, dose nitrifier starter, then wait. Fish-in cycling stresses the animals with ammonia and nitrite spikes, requiring daily 50 per cent water changes to keep ammonia under 0.25 ppm. Use fish-in only if you inherited a stocked tank or are seeding from a mature filter — and even then, a hardy species like tetra handles it better than ornate bettas.
Do bottled bacteria starters actually work?
Dr Tim’s One and Only and Tetra SafeStart contain live Nitrospira and reliably cut cycling time to 7-14 days when dosed correctly. Fluval Cycle and API Quick Start are weaker but still help seed colonies. Refrigerate bottles after opening and check expiry dates — dead bacteria do nothing. Pair starters with an ammonia source; bacteria starve without food. Browse water care and treatment stock for current bottles.
What ammonia level should I dose?
Aim for 2 ppm in a fishless cycle, not 4 ppm. The old “ammonia to 4 ppm” advice came from saltwater protocols and tends to stall freshwater cycles because Nitrobacter is inhibited above 5 ppm nitrite. Janitorial ammonia from any supermarket works if it is fragrance and surfactant free — shake the bottle and check that no foam forms. Dose, wait 24 hours, test, and re-dose only when both ammonia and nitrite read zero.
Why is my cycle stalled at nitrite?
Nitrite-eating bacteria reproduce slower than ammonia-eaters, so a two-week stall around 2-5 ppm nitrite is normal in week three. If it lingers past day 30, check pH — values under 6.4 halt nitrification entirely. Singapore’s PUB tap sits at 7.0-8.0 so this is rare, but tannin-heavy aquasoil tanks can drop below 6.0 and freeze the cycle. A 50 per cent water change with conditioner often restarts progress.
Does aquasoil cycle differently?
ADA Amazonia II and Tropica Aquasoil release ammonia for the first 14 to 21 days of a new setup, effectively cycling the tank for you. Skip ammonia dosing entirely and run the filter for three weeks with daily 30 per cent water changes during week one to keep ammonia under 4 ppm. Test before stocking — premium aquasoils sometimes leach ammonia for 28 days, especially with deep substrate beds.
Can I add fish in stages?
Yes, and you should. Even a fully cycled tank only supports the bioload it was cycled for. Add 25-30 per cent of planned stocking, wait two weeks, test, then add the next batch. This lets the bacteria colony scale up to match the new load. Dumping ten neon tetras into a freshly cycled tank usually triggers a mini-cycle for three to five days.
What test kit do I need?
API Freshwater Master Test Kit at SGD 45-55 covers ammonia, nitrite, nitrate and pH for around 800 tests. Salifert and JBL kits are more accurate but cost more per test. Dipstick strips are unreliable for cycling — they routinely read low on ammonia. A reliable liquid kit is non-negotiable; pick one up alongside basic aquarium equipment.
How do I know cycling is complete?
Three consecutive days of dosing 2 ppm ammonia and reading 0 ppm ammonia and 0 ppm nitrite within 24 hours. Nitrate will read 20-40 ppm at this point — that is correct and gets reset by your first water change. Stock lightly, then test again seven days later to confirm stability under bioload.
Do I keep the filter running once cycled?
Always. Nitrifying bacteria die within 4 to 6 hours without oxygenated water flow. Never rinse media in tap water — chlorine kills the colony. Squeeze sponges in old tank water during water changes, replace at most one media tray per month, and the colony stays intact for years.
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