Today’s lessons are about zones. Zones are important for tanks for many reasons. Understanding the relationship betweenthe zones and what creatures live in the different areas and how they interact will create a healthier and more vibrant aquarium. While this may seem straight forward there are different things that you will need to understand about the way they keep a tank healthy. If you support each level of the tank then you lower your need to use chemicals, and your need to interfere in the tanks cycle, it means less water changes, less cleaning, and healthier and happier fish.
There are 3 zones to a tank, the bigger the tank the larger the zone, and some will say more zones, however at the end of the day there are really only 3 zones to worry about.
1. Top zone
2. Middle zone
3. Bottom zone
The top zone is straight forward; it is about the top ten percent of the tank, and this means from the high water mark down ten to fifteen percent of the tank. This area of the tank is where oxygen enters the system, more on that in a latter post; it is also where food will float. It is important to have at least one top dweller in the tank. This fish, or school of fish will eat most things that sit on top of the tank, it is important because it keeps the surface of the water clean, thus allowing more light to reach the bottom.
The middle zone is the largest zone, some people will sub-divide this zone, but it really is not necessary, this is the area most fish will stay in. It represents seventy to eighty percent of the tank. The fish here keep things moving in the water, they will by their movement keep the plants and other things in the tank clean, they will also eat and disturb things in this zones, again keeping it clean and the water circulating. The filter will push most things into this zone, so it is important to have fish here. The intake for most filter types is also in this zone, which makes it important to have active fish in this zone, the more they move the more the filter will remove.
The bottom zone is the last ten to fifteen percent of the tank. It is where the sand is at the bottom, and more importantly it is where everything will eventually settle. It is very important to have fish here who as they will eat the food that settles. If they are happy and active fish they will also dig and disturb the bottom surface preventing pockets of chemical built up or decaying matter to accumulate. Both of which can be harmful to fish. Their activity will circulate the bad substances in the middle zone and into the filter, thus eliminating the need to manually clean the bottom of the tank.
Using fish in the different zones will keep build up of various decaying matter and natural chemicals that the fish produce, such as waste, circulating in the tank, which means the filter will remove it. If there is little movement in the tank it means things will settle, and then you have to manually remove things, and disturb the bottom of the tank, as well as frequent water replacement. This adds extra stress to fish, something you want to avoid. This means you should have a good filter and clean it regularly, which will be the topic of a future post.