From set up to maintenance, we explain the basics when it comes to establishing healthy water conditions in your fish tank.

Understanding the requirements behind good water quality is the first and most important part of fish keeping. What is the nitrogen ‘cycle’? How do I know my tank is cycled and ready for livestock? What are signs of an unhealthy tank and how do I fix it? What are the appropriate parameters for my aquarium? The answers to these questions will help you to be a more successful fish parent and give you a better understanding of the importance of maintaining the water quality inside your aquarium.

What is the nitrogen cycle (or ‘cycling’)?

The nitrogen cycle is the initial process that all tanks must complete to prevent ‘new tank syndrome’. This is the period of time that the biological filter becomes established with the appropriate beneficial – or ‘good’ – bacteria for long-term health of the aquarium. There are three basic stages of cycling:

  1. Ammonia is introduced to the aquarium via fish waste or uneaten food. The fish waste or uneaten food will break down into ammonia (NH3 and NH4). NH3 is very toxic to fish and will need to be detoxified. You can add treatments to break down or oxidise the ammonia, essentially eliminating it.
  2. The oxidised ammonia will turn into nitrites, which are also toxic to fish and will need to be detoxified with a prime. In the meantime, another type of aerobic bacteria will breakdown and convert the nitrites into nitrates, which are much less toxic to fish.
  3. Nitrates are then removed from the aquarium with anaerobic bacteria that break them down into a harmless nitrogen gas that escapes through the surface of the water.

When is my tank cycled and ready for fish?

Generally, during this cycling process, you will see your ammonia levels rise and fall, then your nitrites rise and fall, and lastly, you will see your nitrates rise. Once the ammonia and nitrites have fallen to zero and you have nitrates set to a good level, you can safely assume your tank has fully cycled – congratulations! In some cases, you may never even see the nitrite portion of the cycle; you will only see a rise and fall in ammonia and then a rise in nitrates. Keep in mind that every tank is different and the cycling times will vary anywhere from a week to a month.

What are signs of an unhealthy tank and how do I fix it?

The most obvious sign of an unhealthy tank is when your inhabitants are not doing well. This could include death, sickness, signs of stress, or anything else that is not considered normal behaviour. (linkto: story not yet published: Fish First Aid) Other signs of an unhealthy tank could be cloudiness, excessive algae and plant or coral deficiency. The first thing you should do when any of these signs are noted is to test the water quality parameters of the tank. If your water quality is good, you must investigate further. Ask yourself: Are there signs of sickness? Are the fish eating? Is there clouding? Once you have found the problem, you can then decide on an appropriate treatment plan. This may include adding a medication or a specific supplement, or performing a water change.

What are the appropriate parameters for my aquarium?

Below is a handy guide for a variety of tank set ups.

Marine (fish only) aquarium

Specific gravity: 1.023 to 1.025
Temperature: 23 to 25°C
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: under 5ppm
Phosphate: < 1.0mg/L
pH: 7.8 to 8.4
Alkalinity: 4 to 6meq/L or 11 to 16dKH
Calcium: 350 to 450mg/L
Magnesium: 1150 to 1350mg/L
Strontium: 4 to 10mg/L
Iodine: 0.06 to 0.08mg/L

Marine reef aquarium

Specific Gravity: 1.023 to 1.026
Temperature: 25 to 27°C
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: under 5ppm
Phosphate: < 0.2mg/L
pH: 8.0 to 8.4
Alkalinity: 4 to 6meq/L or 11 to 16dKH
Calcium: 400 to 450mg/L
Magnesium: 1250 to 1350mg/L
Strontium: 8 to 12mg/L
Iodine: 0.06 to 0.08mg/L

Freshwater community

Temperature: 22 to 27°C
pH: 6.5 to 7.5
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: < 20ppm
Alkalinity: 1 to 2meq/L or 2.8 to 6dKH
General hardness (GH): 1 to 2meq/L or 2.8 to 6dGH

Freshwater planted discus

Temperature: 24 to 30°C
pH: 6.0 to 7.5
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: < 30ppm
Alkalinity: 1 to 2meq/L or 2.8 to 6dKH
General hardness (GH): 1 to 2meq/L or 2.8 to 6dGH

African cichlid

Temperature: 22 to 27°C
pH: 7.8 to 9.4
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: < 40ppm
Alkalinity: 4 to 6meq/L or 10 to 18dKH
General hardness (GH): 4 to 6meq/L or 10 to 18dGH

Feel free to chat to your local Petbarn team member for more advice on your aquarium’s water quality or check out our handy how-to videos on caring for your pet fish. Don’t forget that we offer a free in-store water-testing service. Just bring a sample of your water in a container.

For more advice on maintaining your aquarium, don’t miss our video: