Dynamics of Bacteria
One of the most potent, but invisible, part of the reef ecosystem is that of the bacteria. Different bacteria population wax and wane as the reef conditions change. Even in the most stable of reefs in the wild, the bacteiral composition fluctuates regularly. Similar in our reef aquaria, bacteria plays a key role in keeping the system stable. In fact, we reefers often manipulate bacteria population to tackle various problems in our reef tank.
Therefore it is worthwhile to understand the dynamic of bacteria growth, such that we can have the correct expectation as to how a bacteria product should work.
Most Ideal Conditions
Let's look at the simplest situation, where we start with a single bacterium, and let the population grow. Suppose there is plenty of resources and no competition, how would the bacteria population change?
Bacteria reproduce through binary fission. This is the process wherrby one bacterium splits into two. So the single bacterium becomes two, two bacteria becomes four, then 8, 16, 32..... This results in two very interesting implications.
1. At the early stage, the number of bacteria increases very slowly, it will take a few cycles of fission before there is a meaningful number of bacteria in the system.
2. At the later stage, the bacteria growth is impressive. One trillion bacteria can become two trillion in the same duration as it takes for one bacteria to become two.
For Our Reefs
If we keep this in mind, some of the things we do will make perfect sense.
When we cycle the tank, the bacteria need the time to divide and colonize all surface. Because of the dynamic of how bacteria grow, very often the nitrification capability (which depends on the number of bacteria) stays low for many days. Does adding more bacteria from a bottle help? Not really. The existing bacteria in the aquarium, which have been dividing for a few days, is much more than what little bacteria there is in any bottle.
For those who carbon dose, it is often recommended to start with a smaller amount. The bacteria dynamic explain this very well. At the beginning of carbon dosing, the number of bacteria (the species we want) is low. As a result, they can only make use of a small amount of carbon. The unused portion may end up taking up be nuisance species, causing problems in the aquarium. Therefore, it is prudent to matching the carbon dosing to the bacteria growth dynamic. Which means start with a small amount, and slowly increases as the bacteria grow.
This is a very crude picture of how bacteria work. I will discuss a more realistic model in the next post.