Understanding Aquaponics Filtering Systems

Getting your aquaponics system just right takes time. However, it is worth making the effort to get the system right. Your reward will be a good quality yield of healthy crops with the minimal of intervention from you.

Setting up an aquaponics system is actually fairly straightforward. Unfortunately if you’re not aware of the filtration issues; then you’ll quickly discover that the small pipes moving water round your system can get blocked. This is because the waste particles created by fish are generally small but solid. Without the right help the flow of water is interrupted and the plants cannot get the nutrition they need.

The Aquaponics Filtering Process

Bacteria in your water will convert the ammonia produced by your fish into nitrates which are needed by the plants to ensure healthy growth. Check: What is aquaponics?

This is a natural process which occurs in the wild as well as in your aquaponics system. The plants help to keep your fish healthy by filtering the water and removing toxic elements.

But, not all particles in the system are dissolved. Larger particles of waste and eve left over fish food will be sucked into your pipes. They can then block the flow of water; preventing the plants from getting the nutrients they need and depriving the fish of clean water.

The most likely places to find a clog in your system are the nozzles and piping which carry the water; these are the narrowest parts.

Fortunately this can be prevented by filtering the water when it leaves the fish tank, before it enters the plant base.

Types Of Water Filter

Your fish need clean water in order to remain healthy; this is why it is advisable to filter the water in their part of the system. You can choose between these filters:

  • Swirl Water Features

These are filters that are shaped like small barrels. Inside the barrel is a basket; much like one you would use for your washing. At the base of your basket you can add your choice of filtering material.

swirl or vortex filter

You then allow the water through from your fish tank. This comes in half way down the barrel wall. The fore it arrives with creates a swirl inside the barrel. As the swirl slows the water rises and can go out of the tank and into the plant bed through a pipe at the top of the barrel.

The key to this approach working is that the barrel is large enough to create a good swirl. The high level of flow allows the larger particles to sink to the bottom of the basket and stay there; preventing the hard particles from blocking up the system.

  • Raft Filters

This type of filter looks a little like a raft floating in a large tank.

The large tank of water is split into several sections. Water from the fish tank flows in at the top of the first chamber; where you’ll need to place three types of filter.

raft filter for aquaponics

It is normal to use large foam pieces as the filters; these will trap the larger waste particles and even dirt particles; allowing clean water to move onto the next chamber. The majority of the waste simply floats to the bottom of the tank.

The water only moves between chambers when it overflows. It is a good idea to use two foam pieces to create each wall; this will ensure that you can remove one for cleaning without affecting the next one.

Once the water has been through all three chambers it is clean enough to be pumped back into the plant tank.

Again, the water must be removed from the top. Entry and exit at the top is important to ensure the particles which have settled are not dragged into the plant tank.

It is important to note that the raft system is one of the best you can install but it requires a fairly large tank. You will also need to shut the water off periodically in order to remove the sludge which starts to build up at the bottom of the tank.

  • The Mechanical Filter

It is possible to adapt the above systems to fit your specific needs or even to purchase a pump that is designed to filter water and remove certain materials. However, these are generally very expensive and may not produce any better results than the filters mentioned above. After all a mechanical filter simple applies the same technology as the swirl filter; but with power behind it.

One way of achieving this is to get a pair of tights and cut several sections out of them. These can then be secure over the inlet and outlet pipes of your filter. The tights will be an extra filter, preventing the larger particles from getting into your small pipe work.

You’ll need to empty the tights periodically to ensure they don’t become the source of any clogs.

The Bottom Line

Solid waste particles are heavier than water and will settle given the opportunity. This makes it easier to remove them and protect your system. However, it is worth noting that you can reduce or even eliminate the amount of particles in your system just by following a few simple rules:

  • Don’t over feed your fish; this will prevent fish food clogging your pipes.
  • Don’t use the cheap fish food; it won’t help your fish and it will increase the amount of waste.
  • Don’t have too many fish! Always calculate fish numbers based on the size of the fish when they are adults. Too many fish equals more waste than the plants or your system can handle.

If you are not sure about the quality of your fish food or the filters simply take a look at the roots of your plants. If they are slimy and grey or brown then there is too much debris in the tank; you need to reduce and change the fish food. Getting this one factor right should eliminate the need to add any filtration system unless you’re planning to go into large scale production.

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