Fish constantly excrete waste as they swim through the water. If these wastes are not removed, the toxins that the fish remove from their systems will quickly build up to concentrations high enough for the fish to poison themselves.
The early stages of this are called ammonia stress: when it turns fatal, it’s ammonia poisoning.
Additionally, floating particles in the water and decaying food and other organic matter can contribute to cloudy aquarium water if left unchecked.
Filters for aquariums and fish tanks are responsible for cleaning this water and maintaining a healthy environment for our fish. Next we are going to see how a fish tank filter works to keep the tank water and the fish healthy.
How does a fish tank filter work?
To understand how a fish tank filter works, the first thing to understand is that biological filtration is absolutely necessary in any aquarium to reduce the maintenance required.
Mechanical filtration helps maintain water clarity, and chemical filtration can solve problems with the source water or can be used to remove specific toxins or any medications that get into the system.
It’s important to be aware that the water in your tank can be crystal clear and still be toxic to your fish, or it can look cloudy or dirty and be perfectly safe.
Mechanical filtration, also known as physical or particulate filtration, is provided by pushing the water through some type of filter media that acts as a strainer. This strainer will catch any free-floating particles that cannot pass through the openings in the media.
Typically, it can be found in the form of sponges, sieves, foams, and screens… all capturing solid matter and particles like fish waste, leftover food, debris, and anything else that makes the water cloudy.
Because mechanical filtration doesn’t do much to break down these large pieces of aquarium debris, the mechanical stage of your filter requires the most maintenance: clean the filter foams from time to time with aquarium water.
The quality of mechanical filtration depends on several factors
- First, the finer the medium, the smaller the particles that can be trapped. However, finer media clog much more quickly and must be rinsed or replaced more frequently.
Coarser media will allow more particles to pass through, but will take longer to clog.
Many mechanical filters will use multiple layers of media, starting with coarse media and ending with fine media to provide optimum wet cleaning.
- Second, the longer it takes for the water to go through the filter, the more time debris has to collect in the water or settle, and the cloudier the water becomes, the more debris will settle to the bottom of the tank.
- Third, a mechanical filter will provide better filtration if it is cleaned frequently and properly. Saturation of the filter medium can greatly reduce the efficiency of the filter.
Leaving a dirty and clogged filter cartridge will prevent sufficient water flow or may force water to flow around the filter media instead of through it, preventing the water from being filtered.
Some types of fish foul the tank either through their behavior (such as digging) or through their eating habits. Also, failure to provide enough water changes, overfeeding, and other tank care issues will reduce the quality of mechanical filtration.
Mechanical filtration can also be provided with a settling sump. A sedimentation sump is a slow-moving container of water that allows any heavy particles to settle and accumulate at the bottom. These debris can be collected and removed with a siphon or net when the tank is cleaned.
We continue our how a fish tank filter works by now looking at the biological filtering stage.
Most filters have a chamber containing biological filter media, often in the form of plastic balls with a high surface area to volume ratio.
The water simply flows through the network of holes and voids that these balls create, where it comes into contact with cultures of nitrifying bacteria that colonize the balls (biological media).
When you look at how a fish tank filter works, you realize that this is where the filtration process really comes into play.
How does biological filtration work?
A biological filter will convert toxic ammonia from your fish waste, excess food, and decaying plants into nitrite, and toxic nitrite into nitrate.
Nitrate is relatively harmless, however, if not removed from the tank by regular water changes, nitrate can cause a variety of problems: kidney, liver and eye problems for fish, as well as suppressing their appetite and preventing their gills from absorbing the nitrate. oxygen from the water. Nitrate will also contribute to algae growth.
Biological filtration occurs when water passes over any surface where bacteria that process waste can grow.
This is probably the most important part of the aquarium hobby. Without the proper colonies of beneficial bacteria in your filter, your aquarium water would have horribly high ammonia content, burning off your fish’s scales, inhibiting their respiration, feeding algae, and messing up pH levels.
Another key point in understanding how a tank filter works is that biological filtration takes time to be effective in a new tank. This is because it takes time for colonies of beneficial bacteria to establish themselves, and to grow in numbers that can be effective.
Even the highest quality biological filters cannot process fish waste until the aquarium has been properly cycled.
biological filtration and plants
Plants can use some nitrogenous waste as fertilizer, although they can only process it as they photosynthesize during the day.
The concentration of nitrogenous waste used by plants will be so minimal that there will be no significant difference in water quality. At night, however, plants breathe just like animals, and will produce nitrogenous waste.
The activated carbon will remove chemicals from the water until the carbon becomes saturated. It is very important that any activated carbon filter in your filtration system is changed frequently.
For the chemical filter to work, several conditions must be met:
The entire volume of the tank in water should be moved through the carbon at least twice an hour. If the water is not moving as quickly, it will not be exposed to carbon often enough and not enough chemicals will be removed.
Water that is abnormally hard, very soft, chemically softened or hardened, or has high concentrations of minerals or trace elements will saturate the activated carbon more quickly.
Also, by adding plant foods, trace elements, or mineral supplements to the water, you will also saturate the carbon more quickly, as the carbon removes these chemicals from the water.
changes in the water
Insufficient water changes will allow chemicals to build up in the water, increasing the load on your chemical filtration.
Overcrowded tanks will also increase the load on the chemical filter as well as any other leaks you have.
Another vital point to understand about how a fish tank filter works is that as the carbon tries to continue absorbing chemicals from the water after it becomes saturated, it can eventually begin to release toxins that are not easily bound by the carbon.
These take two forms: substances previously absorbed from the water or substances that are the result of chemical reactions taking place on or due to carbon.
Because of this, it is very important to regularly replace any media containing activated carbon.
Other resins are currently on the market, some of which remove chemicals or specific chemical compounds, others work in the same way as carbon.
Carefully review the instructions for these products to ensure that you are using them correctly and that they can actually help with the problem you are experiencing.
Many resins can be recharged, often using common household methods (such as soaking in a salt bath). Refill methods for chemical resins vary and should be listed (if applicable and safe) on the manufacturer’s packaging. Some resins even need to be prepared or loaded before use.
It is very important for the health of your fish that you read the manufacturer’s label completely before attempting to use chemical resins to help filter your water, as some chemical resins can be lethal to fish if not properly prepared or loaded.
It is vitally important to the health of your fish that you provide them with sufficient filtration. Filtration can make your tank look nicer and will greatly reduce the care required to keep your fish healthy and happy.
But seepage is not an excuse to skip tank maintenance. Your fish will still need proper feeding, tank cleaning, water changes, and regular inspections to prevent stress, disease, or any other problems.