Of all of the miraculous systems Mother Nature has created to maintain harmony and balance, the nitrogen cycle might be one of the most important cycles on earth because it’s the building block of all organic life forms. The more you learn about the nitrogen cycle, the better equipped you will be to understand the changes that occur in your pond and how they relate to the health of your fish and plants.
The nitrification process, or nitrogen cycle, is a biological process that changes ammonia (NH3) to nitrite (NO2) which are both toxic to fish and plants, and then from nitrite to nitrate (NO3). The amazing thing about this cycle is that it can start at multiple points and it has the ability to go backward and forward, allowing for a variety of complex biological processes to occur.
It has been said that the more you learn about any scientific subject, the more you realize you don’t understand about said subject. The goal of this article is NOT to help you defend a doctoral thesis in aquaculture. The aim is to provide you with just enough information so that you have a working knowledge of the science that keeps you pond clean and healthy. Just like the famous little yellow book for computer amateurs, call this article “Water Gardening Biochemistry For Dummies”, if you will.
But, be careful, because even a little learning can get you into trouble. With new found knowledge, some new pond owners start to worry about the water chemistry in their water garden, and begin adding products in hopes of creating the perfect aquatic environment or ecosystem. Note that if your pond is designed and built properly and you clean the debris out of your skimmer on a regular basis, add bacteria, and trim dead aquatic plants, Mother Nature will balance the chemistry in your pond and clean it for you, even if you don’t understand how it works. Think of it this way. Most people really can’t grasp how a computer works; they just enjoy the benefit of owning one. Water gardens are the same way.
Nitrate Producer – The Air, the Rain, the Pond
Basic nitrogen gas (N 2 ) makes up approximately 78 percent of our atmosphere. This form of nitrogen is inert and cannot be used by plants and animals. It makes its way into the pond via the rainwater and takes a great deal of energy to convert it to a form that is usable to plants. Nitrogen gas returns to the atmosphere when it leaves the pond through the evaporation of pond water.
Ammonia Eater – Ammonia Nitrification
The large amount of surface area both on the surface of the biological filter media, as well as the rocks and gravel inside the pond, allows for the colonization of nitrosomona & nitrobacter beneficial bacteria that are responsible for the nitrification process, changing ammonia to less toxic forms of nitrite and the usable form of nitrate. Regular addition of beneficial bacteria such as Aquascape Beneficial Bacteria for ponds helps support the reduction of ammonia.
Nitrate Eater – Aquatic Plants
Nitrate is either absorbed by aquatic plants or, in anaerobic conditions, it goes through the process of de-nitrification, which changes the nitrate back to nitrogen gas. Although uncommon in ornamental ponds, nitrate can also be removed by small frequent water changes if unusually high levels are detected in the water.
Nitrate Producer – Rain and Lightning
Nitrates can also be added to your pond by way of atmospheric fixation. This occurs during lightning storms when nitrogen gas is broken up, allowing it to combine with oxygen-forming nitrogen oxide which is dissolved in rainwater. This is why our lawns become so green following a lightning a storm – it not only receives water, but also a burst of nitrate (fertilizer). This is also why ponds can turn murky or have an algae bloom after a storm. If you add some liquid bacteria such as Aquascape Beneficial Bacteria for ponds immediately after the storm, you can counteract the influx of nutrients.
Ammonia Producer – Fertilizer Runoff
Be conscious of the amount of fertilizer you use around your pond. During a heavy rain or a cycle of over-irrigation, the fertilizer, which is made of ammonia and phosphorus, can wash into your pond creating an algae bloom, water quality problems, or even killing fish and invertebrates.
Ammonia Producer – Dead Plant and Animal Debris
Organic debris like leaves, lawn clippings, and dead fish or insects will break down, forming ammonia as a by-product, starting the cycle of de-nitrification again. Reduce the amount of plant debris in your pond by using a skimmer filtration system which removes plant leaves and debris before it enters the pond. The use of protective netting also helps reduce leaf litter from entering the pond in the fall.
Ammonia Producer – Fish Food and the Resulting Waste
Most of our ponds have fish in them. When the fish are fed, the result is a combination of un-eaten fish food and fish waste. Both contribute to the ammonia level in the pond. Don’t feed your fish more than they can eat in a few minutes. A high-quality fish food is also very important. Aquascape premium fish foods contain probiotics that help fish utilize more food, thereby reducing fish waste and actually help break down waste and other organics found normally in the pond environment.
Ammonia Eater – Oxygen
In the same way a bellows helps heat up the fire in a hearth, waterfalls & streams create the dissolved oxygen necessary to stimulate the nitrification process in your pond. This oxygen is also necessary for the survival of your fish.
The Nitrification Cycle
The chart below illustrates how the nitrification cycle forms a circle of life. In a water garden it takes between 4-6 weeks for the nitrification process to complete a cycle. So if you clean out your pond this spring, only to endure an algal bloom and green water a couple of weeks later don’t fret. If you’ve installed a properly sized biological filter, and you’re adding beneficial bacteria as directed on the package, then you’re only a short while away from crystal clear water.
If you have any further questions regarding pond water quality and chemistry, please feel free to speak with our retail store staff. They love talking about this stuff!