Bacteria Starter: Seeding the Nitrogen Cycle
How a bottled culture of nitrifying bacteria helps establish the nitrogen cycle in a new aquarium and why an ammonia source is needed.
Overview
A bacteria starter is a bottled culture of nitrifying bacteria added to a new aquarium to help establish the nitrogen cycle, and after antibiotic treatments that may have harmed the existing colony. It is intended to shorten the time before a tank can safely hold fish.
The nitrogen cycle
In the nitrogen cycle, one group of beneficial bacteria consumes ammonia and produces nitrite, and a second group consumes nitrite and produces nitrate. Ammonia is highly toxic, nitrite is somewhat toxic, and nitrate is the least toxic of the three. A fully cycled tank reads 0 ppm ammonia, 0 ppm nitrite and some nitrate.
Bacteria involved
The bacteria that convert ammonia to nitrite include Nitrosomonas species, which colonise the surfaces of objects inside the aquarium. Conversion of nitrite to nitrate is carried out by Nitrospira and Nitrobacter. These colonies normally take several weeks to develop on their own.
Why use a starter
Establishing the cycle naturally can take anywhere from a few weeks to months, a period during which a stocked tank is vulnerable to new tank syndrome from accumulating ammonia. Adding bottled live nitrifying bacteria is one recognised method of accelerating the cycle, alongside using mature filter media from an established tank or adding live plants.
Feeding the bacteria
Nitrifying bacteria need an ammonia source to grow. In a fishless cycle this is supplied by dosing a measured ammonia source so the colony has food to multiply. Without an ammonia input, the added bacteria have nothing to process and the colony will not establish.
Practical notes
- Pair a starter with a measured ammonia source for a fishless cycle
- Monitor ammonia, nitrite and nitrate during cycling
- Consider re-dosing after antibiotic treatments that affect bacteria
- Confirm 0 ppm ammonia and 0 ppm nitrite before adding fish