Understanding the nitrogen cycle

How does the nitrogen cycle work?

The nitrogen cycle works like this. Fish in your tank cause waste in the following ways;
1. Fish excrete toxic ammonia as part of respiration,
2. Decaying fish waste creates ammonia
3. Uneaten food also produces ammonia.

The nitrogen cycle then begins.

Special kinds of bacteria go to work on the ammonia and turn it into nitrites (which are also harmful), which are then converted into nitrates (Slightly less harmful).

The bacteria required for this process build slowly on the surface of your filters and gravel. This process can take 4-8 weeks, starting from the day that you first add fish to your aquarium.

How do I get rid of the nitrates?

1. Go slowly.
Add a few hardy fish, which are tolerant of changing water conditions. We recommend no catfish, nothing less then 2cm and nothing overly expensive. You should start with fewer fish than your aquarium can hold, then add any additional fish over a period of weeks, allowing the eco-system in the aquarium to readjust (recycle) in between.

Each step needs to be gradual so the bacteria have enough time to multiply and break down the increasing amount of waste products.

2. Partial water changes.
Every 2-4 weeks you should change 15-20% of the water in your tank. This helps reduce the nitrate level in the water by removing some.

How many aquarium fish should I start with?

Remember a small tank may start with only one fish, where a 50-70L tank may start with 3-4 fish. It doesn’t sound like much, and in the larger tanks you may not even see the fish, but this is the safest way to get the tank going and reduce the potential of losing too many fish, and wasting your money.

When should I add new pet fish?

New fish might find these levels deadly as opposed to the original fish, which have become accustomed to the change. So a basic rule is only add more if the first fish look ok and you have waited a week, a couple of days won’t do. But again just a small number of fish as the bacteria will readjust now to the added levels of fish.

How do I keep my bacteria healthy?

Once the nitrogen cycle has completed the start-up phase, your aquarium will be able to detoxify constant levels of ammonia and other chemicals as long as you maintain the bacteria colony. Keeping those colonies healthy, or optimizing the amount of bacteria in the aquarium can be a function of the type of filtration equipment that you choose to use. See Understanding how your filter works

Other importance maintenance topics

Changing small amounts of aquarium water will ensure water quality is maintained without having major variations in the chemical make up of their environment. Remember they are living in the water, so if you put too much freshwater in, even with water ager, this will effect them and potentially lead to many problems. For more information, learn about the nitrogen cycle [link to information]. A key rule to follow is never change more then 30% of fish tank water at any one time. In fact, it is best to change a smaller amount more often. Constant removal of nitrates will accelerate the growth of your pet fish.

How to change aquarium water

Everyone does fish tank water changes a bit differently. Use a bucket and a gravel vacuum that has a self-starting siphon. As this is an opportunity to get some of the gunk off of the bottom, then use the vacuum to go through the gravel.

For a larger aquarium tank, you can also use a long hose running out to the garden. Fish tank water is full of phosphate and nitrate, which your aquarium plants will love; you don’t need to tip it down the drain.

Fill the bucket with clean water and chlorine treatment. You want to make sure the water is similar in temperature to the fish tank already.

Ways to Attack Aquarium Algae

Any body of water can be subjected to algae problems (pools, hot tubs, ponds) try several of these methods to remove the problem

1. More frequent fish tank water changes
Doing extra partial water changes will remove move waste elements.

2. Get Pet Fish That Eats It

Fish that eat algae
Algae eating fish like Plecostomus or "Plecos" as they are nicknamed will come out at night and do a nice job cleaning up leftover food (that will create more food for algae if not cleaned up) and algae with their sucker mouths. Bristlenose, sucking cats and Otos (Otocinclus catfish) are other fish that fall into the algae eating category although there are others. For example, certain African Cichlids like the Mbuna are algae-grazing cichlids and in the wild, they eat all day like water bound cows scraping rocks for algae. Mollys are another fish that likes to munch on algae.

Snails eat algae
Common snails are another option that will eat algae and are often the by-product of buying live plants since these things multiply like crazy. Just buy one so they don't take over the aquarium tanks. Apple snails are larger and don't seem to multiply as much but be safe and stick to one. If snails do take over your fish tank, you can buy products that will kill them.

3. Add Live Aquarium Plants
Plants are higher on the evolutionary hierarchy and will compete with the algae for nutrients and thus will limit algae growth.

4. Limit The Aquarium Light
Algae need light to live so don't place your fish tank near a window and don't leave the aquarium light on too long. Lights should be on for no more than 8 hours a day. Reduce the light period if you develop problems

5. Aquarium UV Sterilizer
A solution to algae would be to purchase an aquarium ultraviolet sterilizer. You hook one of these along the output from your aquarium filter and the water passes in front of a powerful UV light that bursts the algal spores free floating in your water.

6. Physical Removal
When all else fails, you have to remove algae by hand. This means scraping the aquarium glass with algae scrapers and dipping decorations in a bleach solution (just be sure to rinse everything well before placing it back in the fish tank!)

7. Aquarium Chemicals
As a last resort, you can try commercially available aquarium algae killers in liquid or fizz tabs but this should be as a last resort. The algae are growing in your fish tank because it has favourable conditions. You should try to solve these problems first before resorting to chemicals because if you don't reduce the lighting, or nitrate levels, the algae just will come back.

Also, you can buy phosphate removers that you add to your filter either in powder or mat form, which will reduce phosphate in the water which encourages aquarium plant growth.

Cloudy water in a new home aquarium is usually due to a condition known as bacterial blossom. When you added three dozen pet fish all at once, you placed an extremely high bio-load on the fish tank, which resulted in a large amount of waste being produced suddenly. Bacteria that feed upon those wastes began to grow in large numbers, resulting in cloudy water.

Don't add any more aquarium fish, as you are way overloaded for a new fish tank. If possible, move some of the pet fish out of the tank until you get things under control.

Nitrogen Cycle

Your biggest issue now isn't the cloudy water in your aquarium; it's the ammonia spike that will soon occur (if it hasn't already), followed by elevated nitrites. Both could result in the loss of some or all of your aquarium fish. I'd strongly recommend that you become familiar with the Nitrogen cycle, so you are aware of what will be happening in the upcoming weeks.

Looking after any animal will require some type of maintenance. With aquariums, fish live in their own waste so it becomes the responsibility of their owner to ensure they receive the right conditions for life. Keeping your aquarium as work free as possible actually requires small amounts of work, done every 2-4weeks. In so doing, you'll find that aquarium fish aren't as much work as some other pets.

As an example, for an aquarium around 50L roughly 30mins a month is all you will need to spend in maintaining the aquarium for your pet fish. This includes a bucket of water change, a clean of the glass and a change of filter wool/charcoal. Of course the longer you leave it the more work you may need to perform, but ultimately your pet fish will love you more, plus be brighter and healthy, by doing a little regular maintenance.

Again, remember never change all the water in your fish tank as you will shock the fish, cause potential disease or death and your aquarium filter will not work as well for a while. It will be like starting all over again. If you find that the aquarium tank is quite dirty and the water needs a bit more changed, then perform a small water change every 3rd day for a couple of weeks. This allows time for fish/bacteria to adjust, removes lots of mess and shouldn't alter too much of the aquarium’s water chemistry.