Types of Planted Aquarium Filters – Fluidized Bed Filters

Now that you know the different and critical types of filtration in a planted aquarium, how it relates to Mother Nature’s natural water filtration systems, and how aquatic plants aid in the water’s filtration in our aquariums, it is now time to discuss all about planted aquarium filters. 

Planted aquarium filtration is the lifeline of all the inhabitants in the tank. Aquarium filters remove physical, dissolved chemical wastes and other contaminants from the tank. Without it, you would have to change the water more frequently, and this hobby becomes a chore (you will not be able to enjoy your planted aquarium that way). It simplifies our maintenance and widens the days between water changes.

Furthermore, it affects the health and well-being not only of your faunas but also your plants. Aquarium filters are critical to support life in your tank. As I said before, our planted aquariums are a relatively small and enclosed ecosystem compared to our faunas’ natural environment. We have no running water here, and at the very least, we should replicate their natural environment by using an appropriately sized filter.

The function of an aquarium filter for our planted aquarium is not limited only to provide filtration.

  • A suitably sized aquarium filter can provide the needed water flow or turbulence to distribute the nutrients and CO2 (if you are injecting CO2, prolonging the CO2 bubbles contact with water so it can be dissolved before it reaches the surface).
  • Not just distributing nutrients and CO2, it provides the water current that some fish loves to swim against. Plants swaying with the gentle water current is a sight to behold.
  • A breeding ground for beneficial bacteria to break down harmful Nitrogenous compounds (Ammonia, Nitrites) into less harmful ones (Nitrate).
  • An aquarium filter can also provide the water surface agitation, aerating the water for our faunas and beneficial bacteria’s nitrification activities.
  • It can also prevent the accumulation of wastes, sludge, mulm in the substrate, keeping them suspended/floating so they can be taken in by the filter’s intake.

There are numerous things to consider when buying your planted aquarium filter by providing each filter’s pros and cons. Still, before we get to that and find you the right one (you can even DIY your own filter), you need to familiarize yourself with the different types of filters available in the market. Also, we are on a planted aquarium website. Obviously, we will discuss those popular filters applicable to a planted aquarium. 

So Undergravel filters, you are out! Nobody wants to rescape their planted aquariums every 2 to 3 months to clean the detritus that’s been pinned down by this filter. With the advent of aquascaping, that’s the nail in its coffin.

Types of Planted Aquarium Filters

Fluidized Bed Filters

In its most common implementation, a Fluidized Bed filter is actually a 3 chambered sump separated by baffles as well. The big difference is that the biological media is held in suspension by a pumped water flow or an air pump so that every particle of the media will have a large part of its surface area exposed at any given time to home the beneficial bacteria that will filter the water off of Ammonia and Nitrites.

Numerous kinds of media can be used with this type of filter. The most common are pool filtration sand, white quartz, sintered glass, or K1 media. Depending on your choice, once the media are in suspension in the chamber, their surface area is increased drastically. Every piece of the media is being utilized in its entirety as a colonization ground for the good bacteria. A surface area of about 6000 square feet can be realized in as little as 1 cubic foot of media.

A fluidized bed filter can never act as a standalone filter (since it can only provide biological filtration). It can be used in conjunction with a sump filter, where it can serve as the main biological filtration stage in its dedicated chamber, preceded by a mechanical filtration stage. Or it can be used/inserted as a secondary biological filtration stage to supplement your present system.

How does a Fluidized Bed filter work?

We will discuss how a fluidized bed filter works in conjunction with a 3 chambered sump here in this article. Like the trickle and sump filters we discussed previously, it starts with some overflow system letting the water overspill from your main tank and then will drain into your sump with the help of gravity. If you don’t want to drill holes into your main tank, you can use two submersible water pumps: one from the main tank to pump water out and two, from the last chamber of the sump to pump filtered water back into your main tank. If your sump filter is below the main tank, the pump that will pump filtered water back into your main tank should be more powerful as it needs to overcome gravity.

As the fluidized bed filter is a part of a sump, the media are always submerged in water (how can we held them in suspension if they are not?). The water is routed horizontally (since it is a part of a sump filter). This is done by chambers separated by baffles to route the water. The first chamber is usually where you will put all your mechanical media. The second chamber will be home to your fluidized bed filter. This chamber will also contain your air pumps to be able to fluidize your media. The last chamber will be the holding area, which holds the filtered water before it gets pumped back into your main tank.

Like the sump filter we previously discussed, a sump filter with a fluidized bed filter can be positioned under, overhead, or integral to your main tank.

How do I maintain a Fluidized Bed filter?

Depending on your filter’s design and how you integrate easy access to an effective mechanical filtration, you will not be required to maintain your sump filter with a fluidized bed filter for a very long time and reducing the need for water changes. This means you only have to clean or replace your mechanical media and lets you leave your biological media alone for a long, long time. As the media are in total suspension, they will continually collide with each other, thus knocking off any excess debris while filtering your water. Therefore, eliminating the need for frequent maintenance.

To add to that, do not maintain/clean your filter/media with chlorinated tap water! Always see to it that you clean your filter media using old extracted water from a water change. Tap/chlorinated water can instantly kill the beneficial bacteria you have long-established. Your tank cycling reverts to zero. You will have the agony to repeat it (Hello cloudy water/bacterial bloom!!!).

Squeeze and rinse whatever mechanical media you have with old tank water only from a water change to release all the detritus, muck, organic matters trapped by it. Keep your biological media wet by submerging them, also in collected old tank water. Do not use foams, sponges, brushes, even your fingers, or any abrasive products to scrub them (your biological media). Just rinse them with old tank water.

What should I be aware of when using a Fluidized Bed filter?

Everything that applies to a sump filter applies to the Fluidized bed filter since it is not a standalone filter. You can choose to use the regular biological filter media in your sump filter such as lava rocks, ceramic rings, Seachem Matrix, pumice rocks, K1 (not in suspension), Bakki rolls, etc. or you can choose to use a fluidized bed filter biological filter media that can be suspended like pool filtration sand, white quartz, sintered glass, or K1 media.

A sump filter with a fluidized bed filter biological stage is suitable for large to huge aquariums (50 gallons and up) (most often utilized with monster fish planted or non-planted tanks). But there are smaller tanks that have integrated 3 chambered sump filters (10 to 50 gallons). You can use a fluidized bed filter as your biological stage in the middle chamber.

You can even DIY your tank with an integral sump filter (but that will take away space). There are many DIY designs and tutorials that you can research and implement all over the internet that will teach you to set up your very own sump filter using inexpensive materials. But really, no one can stop you from using an external sump filter with a fluidized bed filter for small to medium planted tanks. I have hobbyist friends that do.

Using a sump filter with a fluidized bed filter biological stage effectively adds more gallons of water to your system. More water means a more stable system. Any Ammonia spikes will likely go unnoticed, and you don’t have to follow the “1 inch per gallon” rule when it comes to stocking faunas. They are usually 1/3 the size of your main tank, but I know hobbyist friends that designed their sump filters equal or even larger than their main tanks. You can not put a larger sump filter than your main tank in terms of volume at the top for obvious reasons. 

Plus, you have a lot more room for your mechanical and biological media, but this means you have to spend more on media. Still, you can use cheap alternative media to replace the commercial ones like pool filtration sand that can be suspended.

Setting up a sump with a fluidized bed filter for a beginner hobbyist might be restrictive due to the higher startup cost (available commercial models or customized ones). Not to mention you have to design the system well (DIY). However, considering a DIY sump filter requires careful planning and design in the event of a power outage to prevent overflow.

You can also set up your very own Aquaponics system with this filter. Aquaponics is a fusion of aquaculture, in which you grow fish and other aquatic animals, then Hydroponics, which is growing plants without soil. Aquaponics combines this symbiotic relationship in which plants get their nutrients from the aquatic animals’ wastes while plants serve as a natural filtration for the water for the aquatic animals’ benefits.

Depending on the size of your main tank, sump filters with a fluidized bed filter take up a lot of space, even though you can keep them hidden under your aquarium cabinet. There is little to no room anymore for your other equipment. A sump filter above your tank may rob you of some room/space to maneuver while working with your planted tank or doing maintenance. Did I not say that it causes distractions on an otherwise pleasant scape?

To summarize, here are the pros and cons of a Fluidized Bed filter:

Below the Tank

Pros

  • provides good mechanical and biological filtration – plus you have a lot of room for your media
  • very customizable when it comes to the filter media of your choosing – those that can be suspended
  • Depending on your filter’s design and how you integrate easy access to an effective mechanical filtration, you will not be required to maintain your sump filter for a very long time and reducing the need for water changes. This means you only have to clean or replace your mechanical media and lets you leave your biological media alone for a long, long time.
  • can be completely hidden from view – you can also hide some of your equipment such as your heater from your main tank
  • ideal for heavy loads – you can get away with overstocking without affecting your water parameters
  • adds more water volume to your system – more gallons of water make for a more stable enclosed ecosystem for your faunas and plants. 
  • Completely customizable – you can design or buy customized ones according to your requirements.
  • Very flexible regarding main tank size – before, sump filters are only meant for huge tanks. But nowadays, they can also be very flexible with small to medium to large tanks.
  • It can be home to your very own Aquaponics system or a refugium. A refugium can allow you to home delicate fish/shrimp species or allow you to grow plants that can assist in nitrates reduction, such as Pothos plants (Epipremnum Aureum).

Cons

  • requires considerable planning and design to prevent flooding as a result of a power outage (if DIY) – this means you have to consider the size of your sump filter that is situated below your main tank to accommodate the extra water that will drain from your main tank (when holes are drilled as an overflow)
  • could be too overwhelming for a beginner in terms of cost (commercial models or customized ones plus the filter media) or when planning and designing (DIY)
  • takes up a lot of space even though you can keep it hidden under your aquarium cabinet
  • Unless you have an overflow box or DIY-ed your own overflow system, you have to drill the main tank, which may not be appealing to some. Also, it isn’t easy to sell your drilled tanks in the second-hand market.

Overhead

Pros

  • can provide good mechanical and biological filtration
  • the suspended media can be another attraction to your planted aquarium, but see cons below.
  • very customizable when it comes to the filter media of your choosing – those that can be suspended
  • Depending on your filter’s design and how you integrate easy access to an effective mechanical filtration, you will not be required to maintain your sump filter and your fluidized bed filter for a very long time and reducing the need for water changes. This means you only have to clean or replace your mechanical media and lets you leave your biological media alone for a long, long time.
  • Can return highly oxygenated filtered water – the draining of filtered water from an overhead sump into your main tank will create water surface agitation, which will oxygenate your water.
  • Ideal for heavy loads – you can get away with overstocking without affecting your water parameters
  • no need to plan for a power outage to prevent flooding – sump filters positioned over your tank are designed that, in the case of a power outage, the water will not drain completely due to the baffles design, keeping your filter media wet until the power comes back on.
  • can be home for your very own Aquaponics system – can grow terrestrial plants

Cons 

  • it causes distractions on an otherwise pleasant aquascape of the main tank
  • could be too overwhelming for a beginner in terms of cost (commercial models or customized) or when planning and designing (DIY)
  • may rob you of some room/space to maneuver while working with your planted tank from the top or doing maintenance
  • You must put a pump inside the main tank (another eyesore and equipment in the tank) to pump water into the overhead sump filter. The pump’s power and height of the sump filter is another concern making sure that the pump of your choosing can overcome the force of gravity.
  • Adds to the weight from the top of your main tank – limiting you only to use light-weight filter media – imagine the weight of a sump filter stuffed with filter media, full of water, adding more stress to your main tank’s structure.

Stressing This Out Again!

Whichever filter you had chosen from the list above, do not maintain/clean your filter/media with chlorinated tap water! Always see to it that you clean your filter media using old extracted water from a water change or a water source known to have no chlorine. Tap/chlorinated water can instantly kill the beneficial bacteria you have long-established. Your tank cycling reverts to zero. You will have the agony to repeat it (Hello cloudy water/bacterial bloom!!!).

Squeeze and rinse whatever mechanical media you have with old tank water only from a water change to release all the detritus, muck, organic matters trapped by it. Keep your biological media wet by submerging them, also in collected old tank water. Do not use foams, sponges, brushes, even your fingers, or any abrasive products to scrub them (your biological media). Just rinse them with old tank water.

Conclusion

This article concluded the importance of a carefully chosen planted aquarium filter and how critical it is to support life in our tanks. It can distribute nutrients and CO2 across the whole tank and provides the water current that fish loves to swim against. It can also be a breeding ground for beneficial bacteria, provides the needed water surface agitation, oxygenating the water for our faunas, and nitrification activities.

Last but not least, of filters you can use in a planted aquarium is the Fluidized Bed Filter. It is not a standalone filter since it can only provide very effective biological filtration, but it can be used in conjunction with a sump filter, where it can serve as the main biological filtration stage preceded by a mechanical filtration stage.

In its most common implementation is actually a 3 chambered sump divided by baffles. The biological media is always submerged and is held in suspension by air pumps so that every piece of the media will have its large part of its surface area exposed at any given time to home the good bacteria. 

We also discussed how it works and what applies to a sump filter, is also applicable to the fluidized bed filter and its pros and cons. The only difference is the media that can be held suspended: the most common are pool filtration sand, white quartz, sintered glass, or K1 media.

Closing Remarks

I hope you enjoyed this article. If you have additional questions or want to share your experiences with the Fluidized Bed Filters you used, please leave a comment below.

Next, we will be discussing the “What to Consider when Buying a Planted Aquarium Filter.”


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