The concept of filtration is fairly simple.
Dirty water goes in, filter removes the bad stuff, clean water goes out.
Right? Everyone knows that.
Filters are essentially made up of 3 things i.e. housing, pump and media.
So let’s say it again.
Dirty water goes(via the pump) in (the housing), filter(media) removes the bad stuff, clean water goes out.
Housing is the body of a filter that holds media and/or water pump. It can refer to the plastic container, a tray or a sump, anything that holds your media really. The type of housing of a filter determines what kind of filter it is. And of course, the housing will affect how water flows through the media. But the concept is the same, i.e. moving water from the tank, through the media and back to the tank. That’s it.
A motor that moves water through the housing and back to the tank. The pump capabilities/size is measured by LPH (litres per hour). The higher the LPH, the more flow it gives. However, bigger is not always better. High flow is better for mechanical filtration but low flow is better for biological filtration.
This is the essence of a filter. This is what your pump moves the water through to clean your water. Think of it as a water filter, moving tap water through the carbon to remove chlorine, same thing. Except a tank filter need to remove more than that. Tank water will have debris, poop, uneaten food, ammonia, nitrite, nitrate and the media will remove most of this.
There are 3 different types of media, namely mechanical, biological and chemical medias.
Mechanical media (e.g. sponges, wool) is the first line of filtration in any filter. It prevents debris from clogging your biological media. This keeps the surface area on the biological media free for good bacteria to thrive. This also means that your mechanical media is the easiest to get dirty and needs replacing.
Biological media (e.g. ceramic rings) are basically houses for good bacteria to live. The more porous the biological media is, the more surface area it has and the more good bacteria can live in. More good bacteria means more ammonia can be converted to nitrite then nitrate (see THE N2 CYCLE). But bacteria needs time to process the ammonia and that’s why a low water flow is preferred.
Chemical media (e.g. activated carbon) is like your water filter. It removes chemicals such as chlorine in the water. Not that commonly used and it requires replacing every couple of months and can be costly. It can help with water discoloration.