What Is A Mini-cycle?

[unknowntbeast]

What is a mini-cycle? When does it happen? Why does it happen? Is it...good? Bad? Preventable? Inevitable?

 

[fatheadminnow]

A mini cycle is more or less inevitable and bound to happen through the course of a fully cycled and matured tank.

Lets say you add 3 new fish to your 6+ month fully cycled running tank. Well the bacteria in your filter are established to process the amount of ammonia that your current fish population is giving off. So by adding 3 new fish, you are going to have more ammonia produced which is going to cause a "mini cycle" where the bacteria in your filter have to colonize more to process the extra ammonia.

Any reading in ammonia or nitrite above 0 ppm on our test kit is potentially bad/fatal to our fish.

Also, a mini cycle can happen to a poorly maintained tank, where the fish waste and left over food builds up over time casing an ammonia spike, hence, a "mini cycle."

There are many different ways that a mini cycle can occur. Remember, if you have an ammonia spike for what ever the reason, and you don't do a water change to bring it down, you are going to have a mini cycle, where the bacteria have to colonize more to process the ammonia.

My advice to you is: do weekly water parameter checks to see if they are good. Make sure you stay on top of your 10-25% or so weekly water changes, and when you perform those water changes make sure you gravel vac to suck up left over fish food, waste and other debris.

In other words, keep you tank, filter and other equipment that keep your tank running the way it is, in good, clean working order.

-FHM

 

[OldMan47]

FHM has given a good description of when you might expect a mini-cycle. The essence of a mini-cycle is that your chemistry deviates from the ideal for a short time because of changes in the biological load or the biofilter bacterial colony. There are quite a number of things that can initiate a mini-cycle but as long as it is small and short lived, it is not a real problem to the fish.