Filtering your aquarium is a crucial component of maintaining a healthy stable system. Whilst there are similarities to freshwater fish keeping which have been carried over to the marine side of the hobby there are couple of components which are exclusive to marine fish keeping. In this blog we're going to cover the types of filtration you can set up in your system and the pieces of equipment you will need to enable them.
When we talk about filtration in the marine hobby we can break it down into three types; mechanical, chemical and biological. Many reefers use a combination of one or more of these types of filtration in order to maintain their system.
Mechanical Filtration.
This involves using a filter media that water passes through. The media will catch and remove waste which is suspended in the water. An example of this would be filter socks or an automatic filter roll. Filter socks will need regularly changing and cleaning though else the waste trapped in the media will decompose and pollute the water. An automatic filter roll will reduce this task for you by automatically replacing the used filter media. There is a more in depth blog post about Automatic Filter Rolls at the link directly below.
CLICK HERE FOR A BLOG ABOUT AUTOMATIC FILTER ROLLS
A constraint of mechanical filtration like filter socks is that they are limited to filtering out detritus of a certain size, smaller pieces of detritus or liquid waste will not be filtered out. This is where protein skimmers come in. Protein Skimmers are a means of mechanical filtration which will remove smaller bits of detritus or liquid waste via a venturi. The protein skimmer combines water and air in a contained housing. The air forms bubbles which rise to the top of the housing. Small bits of detritus, liquid waste and organics will stick to the bubbles and rise with them to the top. These bubbles build up into larger bubbles which eventually form a foam which then overspills into a collection cup. Over time this cup will fill with concentrated waste which can then be poured away, thus removing waste from your system. Protein Skimmers are exclusive to the salt water hobby because they only work in salt water. In order for the bubbles to form a foam a degree of water tension is required which salt water possesses whilst fresh water does not.
Chemical Filtration.
Chemical filtration involves the use of media which changes the chemical composition of the water, often by absorbing something from it. The chemical media will essentially remove contaminants from the water which the media is specifically engineered to remove. The two most commonly seen chemical medias in the hobby are Granulated Ferric Oxide (GFO) and Carbon. GFO such as Aquaforest Phosphate Minus helps to manage phosphate by absorbing it, you then remove the spent media and replace it with new. You can use it by fluidising it in a reactor such as the DD Fluidised Reactor or by running it passively in a filter bag placed in a high flow area of the sump. Carbon on the other hand will help to remove pollutants and tannins from the water which give your water a yellow tint. Carbon such as Nyos Active Carb can be used passively in a media bag and placed in a high flow area of the sump. It is important not to fluidise Carbon as it can break down into small pieces which will then enter the water column and can irritate fish and coral due to abrasion.
Biological Filtration.
This relies on micro organisms present in the reef tank such as bacteria consuming waste and converting or neutralising it thus contributing to a healthy marine aquarium. This is why there is often such an emphasis placed on the use of Live Rock. Live Rock contains numerous micro organisms and bacteria which make up a significant proportion of biological filtration. You can therefore use Live Rock in your display and augment it with rock pieces in your sump which is a key part of the 'Berlin Method'. You can also make an effort to support the micro organisms food web by establishing a refugium in your sump. This is a section of your sump which houses some macro algae which absorbs nutrients as it grows. You then remove a portion of the algae thus removing the nutrients it has absorbed to grow. The other part of having a refugium is that this is a perfect habitat for micro organisms and the like to exist which contributes to the overall biological filtration. Another option is to support the bacteria in the tank by dosing a carbon source such as Bio Pellets like the Arcadia Bio Pearls. These require a reactor to be fluidised and the output of that reactor must be pointed directly towards and in close proximity to the inlet of a protein skimmer.
To summarise, there are three main types of filtration all of which have different media and equipment which can be employed to filter your aquarium. Most hobbyists deploy a combination of the different types. At Rock n Critters we use a combination of filter socks (mechanical), live rock (biological) and, GFO (chemical) in order to produce a well rounded filtration method. This is a good starting point if you are just entering the hobby and if you wish to explore other options then you can add them into your method as you see fit. Many different hobbyists have many different methods but the component parts will ultimately fall into the three types of filtration. So now you know, and if you have any questions or want to see the filtration we use at the shop in action then pop over and take a look, we'll be happy to talk you through it and show the options available to you.