Before we can talk about beneficial bacteria in your pond, it is important to understand the basics of why you use them.
Bottom line – the water will be healthier faster if you add them. If you do not add them yourself, the beneficial bacteria will appear but it will take them anywhere from a month to eight weeks to become effective.
If You Have Fish in Your Pond
And we really only worry about adding pond bacteria if we have fish in the water. If no fish, then in a practical sense, it is not vital to add beneficial bacteria. (useful but not vital to the plant health)
This is the kind of large pond that deserves to be kept clean
Nitrogen Cycle – The Simple Explanation (but useful to know)
We add beneficial bacteria to deal with the”Basic Nitrification Cycle”.
Now before you go and turn off your mind with this term, it really only means that fish excrete waste and this waste is ammonia and the water has to handle this poisonous material if it is to remain healthy.
Bacteria have been doing this in nature and we need to establish these beneficial bacteria in our pond. That’s the basics.
While the ammonia and nitrites are poisonous to fish and plants, nitrates are not.
All this happens in the biofilter and you can see why it is important to have this filter properly sized for the pond and the number of fish you intend to keep.
Why It is Important To Size Your Biofilter Properly
If the fish produce more waste (ammonia) than the biofilter can process, your pond will go out of balance and you’ll have water problems (dead fish included).
And just to make life even more interesting, the kind of fish you keep can determine the load on the filter. For example, koi are huge feeders and eat approximately three times more than goldfish. This means that they excrete three times more than goldfish too. (roughly). If one koi excretes three times the ammonia as a goldfish, you can keep one koi or three goldfish of the same size for the size of the filter. In other words, you can keep three times more goldfish in the same pond than you could koi.
The Problem with Overfeeding Fish
If you overfeed your fish, you’ll also have higher levels of ammonia to deal with.
Remember that in a natural lake, the fish population is not as concentrated as in your pond, the population densities are much lower. And this gives the natural filters time to do their work; the beneficial bacteria congregate on all the minute cracks in rocks, between sand grains, etc to work on converting pond ammonia.
Beneficial bacteria also require oxygen to survive. This is why it is important to have a good water flow so that the oxygen can be absorbed by the water. This absorption takes place at the water surface and if the water is kept moving, more oxygen molecules can be put into contact with water molecules.
Role of the Biofilter in All This
The biofilter then is a critical component of our pond as it works to keep the bacteria alive and also as an effective interface between oxygen and the water surface. You’ll find an entire industry advocating that you use its filter material to produce this interface. As a rule of thumb, the more surface you can create for bacteria to live in your biofilter, the better.
And yes, you do have to run your filter 24/7 if you want your pond to stay healthy and alive. The minute you take the oxygen away from these nitrifying bacteria, is the minute the bacteria start to die and your pond starts to go bad.
Small ponds (hard plastic preformed liners) can use filters that are installed in the pond. Bigger ponds will require a separate biofilter.
Remember that is easy to create a system where there isn’t enough oxygen in the water to handle the bio-load. It is impossible to put too much oxygen into the water so do design a beneficial bacteria system that will handle your projected fish and plant counts.
The Bottom Line
Beneficial bacteria jump-start the workings of the bio-filter and are a way to get your pond clear faster in the spring. Not necessary as Mother Nature will do it but still – faster to get rid of green water and get that filter working.