How to Set Up and Cycle a New Fish Tank

Buy Your Supplies at Aqua Nook:

• Tank 
• Filter
• Heater (if the livestock you have planned will
  require one)
• Thermometer
• Substrate
• Gravel 
• Aquarium Sand
• Aqua-Soil
• Rocks, Driftwood, Decorations
• Water
• Ammonia (Dose Ammonia to 2 ppm) 
• Bacteria starter or cycled media (for faster cycle)
• You may also add live plants at this time (but not needed to cycle tank)
• DE chlorinator if using tap water
• Ammonia Test
• Nitrite & Nitrate Test Strips
• Fish tank light (not needed for tank cycle but most individuals prefer to have a light on their tank, if adding plants right
  away with tank set up a light is required)

Optional Supplies:  

• Gravel vacuum
• Water Jug(s) for RODI water

This is a fishless cycling process. Do not add fish, shrimp, snails, or other animals while dosing ammonia.

Step 1: Position and prepare the tank.

Place the aquarium on a level, sturdy stand designed to
support its filled weight. Keep it away from direct sunlight and heating or
cooling vents. 

Step 2: Add substrate and decorations.

Add aquarium-safe gravel, sand, or aqua-soil, along with
rocks, driftwood, and decorations. Follow the substrate manufacturer’s
preparation instructions; some substrates should be rinsed, while others should
not.

Step 3: Install the equipment.

Install the filter and filter media. Add a heater if needed
for your planned livestock, and a thermometer. Leave electrical equipment
unplugged until the aquarium is filled and the equipment is ready to operate
according to its instructions.

Step 4: Fill the tank and condition the water.

Fill the aquarium with water suitable for your planned
livestock. If using tap water, add an aquarium water conditioner that treats
both chlorine and chloramine, following the label instructions.

Step 5: Start the filter and heater.

Turn on the filter and any needed heater. Make sure water is
circulating and the surface is moving to provide oxygen. Keep the filter
running continuously throughout cycling and after animals are added.

Step 6: Add live plants, if desired.

Plants can be added during setup. Provide lighting
appropriate for the plants. Plants are optional for cycling; an unplanted
aquarium does not need its light on during the process.

Step 7: Test the starting water.

Test and record ammonia, nitrite, nitrate, and pH. Some
water sources and aqua-soils already contain or release ammonia, so check
before adding any.

Step 8: Add beneficial bacteria and an ammonia source.

Add an aquarium bacteria starter according to its
instructions, or established filter media from a healthy aquarium.

Use an aquarium ammonium chloride product intended for
fishless cycling. Follow its instructions to reach approximately 2 ppm
ammonia, accounting for any ammonia already present. Dose for the actual
water volume, allowing for space occupied by substrate and decorations.

Step 9: Test and monitor the cycle.

Test ammonia and nitrite every one to two days, and check
nitrate and pH periodically. Record your results.

As the biological filter develops, ammonia is converted into
nitrite, then nitrate. You may not see every stage clearly, especially when
using established media or bottled bacteria.

Step 10: Confirm that the tank is cycled.

When ammonia and nitrite both read 0 ppm, add a
measured ammonia dose according to the product’s instructions to reach
approximately 2 ppm.

There will likely be nitrates at this stage.

Test again after 24 hours. If ammonia and nitrite
both return to 0 ppm, the tank has passed this cycling check. If either
remains detectable, continue cycling and repeat the check once both return to
zero.

Step 11: Prepare for the first animals.

Perform a water change as needed to bring nitrate into a
suitable range for your planned livestock. Condition replacement water prior to
adding water to the tank and match its temperature. Confirm that ammonia and
nitrite remain at zero and that temperature and other water parameters suit the
animals.

Step 12: Add livestock gradually and continue testing.

Begin with a modest number of appropriate animals. Stop
dosing ammonia before adding animals. Check ammonia and nitrite daily
during the first week and after later additions.

Continue regular water changes and filter maintenance. A complete
cycle establishes biological filtration; it does not eliminate the need for
ongoing aquarium care.

What is a fish tank cycle?    
The bacterial cycle of a fish tank—known as the nitrogen cycle—is the natural process where beneficial bacteria convert toxic
fish waste into safe compounds.

Why is waiting to add fish and invertebrates to a cycled
fish tank important?

Fish and invertebrates continuously produce waste (via gills, urine, and feces) that breaks down into ammonia. In a
brand-new tank, ammonia rapidly accumulates to toxic levels, causing severe gill damage, suffocation, and death.

Introducing livestock too early forces them to live through ammonia chemical burns and severe physiological stress. This stress can also lead to death or shorten the lifespan of your animals. 

What is happening after and tank is successfully cycled:

Beneficial bacteria convert toxic ammonia into less harmful chemical compounds through a biological process called the nitrogen cycle.

What Happens in a Cycled Tank?

Beneficial bacteria help process waste and keep the water safer for your fish:

• Step 1: Ammonia becomes nitrite.
  Fish waste, uneaten food, and decaying plants produce ammonia. Bacteria convert ammonia into nitrite. Both are toxic to fish.
• Step 2: Nitrite becomes nitrate.
  Bacteria convert nitrite into nitrate, which is much less toxic. Nitrate still needs to be managed through regular water changes. Live plants can also help by absorbing it as they grow.

Ammonia → Nitrite → Nitrate

In a properly cycled tank, ammonia and nitrite should remain at 0 ppm. Regular testing helps you confirm that your biological filter is keeping up with the waste produced.

Why Does a Cycled Tank Still Need Water Changes?

Cycling helps your tank process waste chemicals, but it does not remove everything that builds up in the water.

Regular partial water changes help:

• Lower nitrate: Beneficial bacteria turn ammonia and nitrite into nitrate, which can become harmful as it accumulates.
• Dilute dissolved waste: Other waste products can build up even when the water looks clear. Siphoning the gravel is a good strategy to remove detritus buildup.
• Maintain water balance: Properly prepared replacement water helps replenish minerals and buffering capacity used over time.