Explaining the Nitrogen Cycle

Why is my water cloudy?

White, cloudy water can be caused by several things, but most commonly it is due to a “bacteria bloom.” A “bacteria bloom” is usually associated with “new tank syndrome”. Ammonia builds up in the aquarium and the nitrogen cycle begins. As the bacteria establishes itself, it floats through the water creating a cloudy appearance. A “bacteria bloom” can also be caused by sudden increases in ammonia due to overfeeding or excess organic waste and decay. Losses of large numbers of bacteria due to power outages or other circumstances can also cause blooms.

Test the aquarium water for ammonia and nitrite. If either of these compounds are present, a bacteria supplement should be added. Do not do a water change unless levels are dangerously high, or fish show signs of stress. Changing water will only lengthen the time needed for the bacteria to establish itself.

If the tank is an established aquarium (livestock has not been added in the past 2 months or longer) be sure you are not overfeeding. If the problem persists there may be too many fish in the aquarium for the biological filter to adequately handle. This forces the bacteria to float freely throughout the aquarium. Additional biological filtration will need to be added or some fish may need to be removed from the tank.

The Nitrogen Cycle

The Nitrogen Cycle is the most important and fundamental principle of controlling a closed aquatic environment. No one should begin an aquarium without fully understanding what the Nitrogen Cycle is and how it works. The illustration and the description explain the four steps in the Nitrogen Cycle.

First:
Fish waste, excess food, and other decaying organic material break down into a toxic chemical compound called ammonia. Even in low levels, ammonia is toxic to fish.

Second:
Beneficial bacteria living in the filter and on surfaces in the aquarium convert ammonia into nitrite. Nitrite is also a toxic chemical compound, equally as harmful to fish as ammonia.

Third:
The nitrite is converted by another beneficial bacteria into a far less toxic compound called Nitrate. Small amounts of nitrate are completely normal in aquariums. For freshwater aquariums, levels under 30 ppm are considered safe, while levels in saltwater tanks should stay under 20 ppm. Be sure to regularly monitor nitrates with a nitrate test kit

Fourth:
Nitrates can be removed in several ways. The most effective way is to perform regular partial water changes, removing about 25-30% of the water in the aquarium and replacing it with fresh dechlorinated water. This should always be the first thing you try to get nitrate levels down. Removing excess waste by siphoning the gravel or cleaning filter cartridges will also help keep nitrate levels low. Small amounts are also absorbed naturally by plants and algae. If problems persist, nitrate-removing filter media or protein skimmers may be needed. Nitrate-removing media will help biologically remove nitrates, while protein skimmers will remove organic waste before the Nitrogen Cycle breaks them down into nitrate. Note: Some home water supplies contain nitrates. Water changes with this water will not be effective. A reverse osmosis (RO), distilled, or spring water may be necessary in this case. See an expert for recommendations on what will work best for your aquarium.

Starting the Nitrogen Cycle

When starting a new aquarium, it is important to establish a good “bacteria bed” for the nitrification process. This is best accomplished through fishless tank cycling and the use of bacteria supplements available from various manufacturers.

A good source of oxygen and a large amount of surface area to house this bacteria must be provided. Various filter media are available to provide housing for aerobic bacteria in canister filters,power filters,, and internal filters. Ceramic media is the most porous option available, making it one of the best options. Filters and filter media are limited to the amount of bacteria they can house, thus limiting the amount of fish that can safely be kept in the aquarium. This makes testing the water and limiting the number of fish kept in an aquarium extremely important.

Fishless Cycling

“Starter Fish” were once commonly used to start the Nitrogen Cycle in new tanks, but fish death is common during the Ammonia and Nitrite spikes of the cycling process. Fishless cycling is much safer and can be done before adding any new animals to the tank.

First:
Set Up Aquarium & any applicable filtration & heating equipment.

Second:
Add Water (dechlorinated) to the aquarium & ensure the equipment is running & temperature is appropriate.

Third:
Introduce 1 small pinch of fish food per 20 gallons every two to three days or until ammonia is present. Alternatively, use a liquid ammonia product such as Fritz Fishless Fuel or Dr. Tim’s Ammonium Chloride Solution.

Fourth:
Use A Bacteria Supplement (i.e. Stability, Nite-Out, FritzZyme, etc.). Follow the instructions on the label.

Fifth:
Test water parameters (Ammonia, Nitrite, Nitrate) every 2-3 days to check your process in the cycle. Ammonia & Nitrite will spike. During this time, the water may look cloudy or murky. This is normal and means beneficial bacteria are beginning to establish themselves in the aquarium. When Ammonia and Nitrite come back down to zero, you’re ready to add fish.

Sixth:
Introduce small quantities of fish every 3 to 4 weeks until you reach the desired number of fish or until your tank is at its maximum capacity. It can help to add a dose of a bacteria supplement when adding new fish to prevent ammonia from spiking with the new addition.

Recommended Items for a Successful Aquarium:

Freshwater Aquariums

Saltwater Aquariums

This uses much of the same equipment as freshwater. Additional equipment is needed and optional equipment found under Saltwater Reef Aquariums may also be beneficial.

Saltwater Reef Aquarium

Or saltwater aquarium with invertebrates

Additional Equipment