The terms “bacteria” and “enzymes” often are used interchangeably. But in

fact, they are very different. Bacteria are living organisms, enzymes are

chemicals. Nitrifying bacteria and enzymes work together to digest organic

waste such as fish waste, uneaten food, and plant materials. When nitrifying

bacteria is introduced to the water garden or filter media, they take some

time to acclimate themselves to their surroundings. It typically takes

anywhere from 21 to 36 days for a nitrifying bacteria colony to reduce

ammonia to nitrate.

Bacteria produce enzymes, which in turn, help the bacteria in their

digestion of organic waste. The enzymes “rip apart” waste and debris into

smaller particles to be digested by the bacteria. As a comparison, our own

bodies produce enzymes, which aid in the digestion of food.

For a long time, single strained bacteria digestants have been developed and

have provided reliable control accumulated organic waste. However, since

such waste problems have become more complicated, multi-strained bacteria

digestants have been developed to handle more complex materials that make

up the organic bio-load of a pond.

Getting the right combination of bacteria strains to eliminate certain types

of waste is the key. Each bacteria strain produces different types of

specific enzymes. Some enzymes break down proteins for bacteria to digest,

some starches, some carbohydrates and other oils, fats and greases. Since

the bacteria and enzymes work as a team, the strains of bacteria selected

for an application are crucial factors.

It is important to the efficient reduction of pond wastes that the water

chemistry promotes healthy bacteria colonies. The conditions within pond

water are not homogeneous. The water chemistry at the far end of the pond

does not represent those within the biofilter media. It is critical that the

pH of water supporting nitrifying bacteria be within 6.0 and 8.5. And the

water temperature is between 70 and 85F, otherwise the amount of waste

reduction will be a small percentage of what is expected and needed to

occur.

Nitrifying bacteria require a minimum dissolved oxygen concentration of 5

mg/l to reduce ammonia and nitrates to nitrite. Denitrifying bacteria that

reduce nitrate to nitrogen gas and water do not function in the presence of

oxygen. Their environment must not contain more than 1 mg/1 of dissolved

oxygen.

The natural consequences of a flourishing nitrifying bacteria population in

the pond and bio-filter media are a lower pond water pH. It would be useful

for the hobbyist to include a sachet of oyster shells in their filter media

bed to replace the carbonate, which is consumed by these bacteria. This

would also reduce the range of daily swing and spikes in the pond water’s

pH.