If you plan on adding fish to your mini pond, a little lesson in understanding the freshwater aquarium nitrogen cycle is a must. But why an aquarium nitrogen cycle and not a pond nitrogen cycle? Well, you might wonder. They are the same thing, really, just different vessels holding water.
Here’s a quick explanation of the nitrogen cycle of a freshwater system without getting too scientific; it’s a natural process of a few steps breaking down fish waste with the help of different types of nitrifying bacteria. In the first step, fish waste breaks down into a compound called ammonia. Second, specific bacteria eat the ammonia and convert it into nitrite. Third, another specific bacteria eat the nitrite and convert it into nitrate, completing the nitrogen cycle.
Both ammonia and nitrite in high levels can be harmful to fish and other pond inhabitants. Nitrate is harmless to fish but can affect health with higher concentrations and can be managed with partial water changes and plants.
For a visual of the process, here’s a look at the aquarium nitrogen cycle.
The Biological Filter – Where Nitrifying Bacteria Live
If you’ve ever had an aquarium, I’m sure you’ve had some water filter, an air stone running through a sponge, or an under gravel filter. If not, and your first learning about it, these filter types are what keeps the water clean, inhabitable, and free of debris in an aquarium.
There are three types of filtration in the aquarium hobby, and I’ll explain shortly what each are but will focus mainly on biological for mini ponds.
- Biological Filter is where the bacteria live and populate, such as gravel or filter sponge, for the nitrogen cycle to happen. The whole system or the area underwater becomes the biological filter because the bacteria live on the all surfaces such as the pond walls or tank glass, gravel, decorations, and plant surfaces, forming a biological film. The bacteria only live on these surfaces and do not populate the water column.
- Chemical Filter is the use of specific media to remove chemicals in the water. For example, granular activated carbon is one of the main products used as a chemical filter to remove organics in the water, keeping the water crystal clear.
- Mechanical Filter uses a filter mesh or fiber to catch larger floating debris, such as uneaten food and fish waste. It helps keep the water column clear of unsightly particles and can be removed before the fish waste or uneaten food breaks down into the first step of the nitrogen cycle.
Which Filtration for a Mini Pond?
You can definitely use all three in a mini pond, but the biological filter will be the most important. Why not use a chemical or mechanical filter? These types require additional equipment such as air or water pumps with air tubing and electrical wiring, which can take away from the simplicity of a mini pond.
With that in mind, the biological filter is what we rely on when keeping fish in the mini pond, but the bacteria don’t arrive overnight. So, naturally, it takes time for the biological filter to develop; in fact, up to a month to a month and a half for it to be established after setting up your mini pond.
So as a warning, do not plan on adding fish soon after a new mini pond is set up. Without the nitrifying bacteria established to process ammonia and nitrite, they can reach harmful levels detrimental to the fish.
Instant Biological Filter – Add Fish in a Day
Thanks to science, there has been a breakthrough in instantly establishing the nitrifying bacteria in a newly set up pond. Dr. Timothy Hovanec, Ph.D. in Ecology and avid aquarist, researched and isolated the bacteria found in the nitrogen cycle within freshwater aquaria.
He then proceeded to develop a product called ONE & ONLY® Nitrifying Bacteria. Bacteria in a bottle that has been used for years in the aquarium hobby to eliminate the new tank syndrome- when ammonia and nitrite rise to toxic levels.
Easy to use, shake and pour in and let the bacteria settle into the gravel or substrate used. You can’t overdose on the bacteria either. Once added, the bacteria will need some food, so adding one or two pond fish is okay. From experience, start slow with a couple of small fish.
Depending on how big your mini pond is, two fish might be enough; otherwise, wait a week or two to add more. The bacteria are slowly multiplying to accommodate the amount of waste the fish produce, so slow and steady when adding more fish to the pond is a good idea.
Keep it Simple – A Little Knowledge Helps.
Setting up a mini pond can be quick and easy after collecting basic materials; a ceramic or plastic pot, substrate of choice, plants, add water, and you’ve got a mini pond.
But if you want to add fish, well, that only requires a bit of knowledge of the nitrogen cycle. Hopefully, this blog has given you enough information and confidence about the subject of fishkeeping to keep them alive. However, there’s so much more to learn about fishkeeping for mini ponds, and more about it will come soon shortly.
So just as easy as the setup of a mini pond sounds, keep it simple when adding fish. Either let the biological filter develop naturally over the 30-45 days or instantly start it with bacteria in a bottle. There’s no wrong way to go about it.
Questions? – There are no bad ones
Please ask away any questions you have, and let’s keep the discussion going. This site is about learning and exchanging ideas, so I’ll do my best to help.