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.
  • It is 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

Canister Filters

Canister filters are more powerful and larger than most other filters, and they are suitable for medium to large planted aquariums. This means you can stuff more media due to its larger capacity/volume, which in turn allows for better filtration and more beneficial bacteria colonization. The simple fact is the more volume your filter has, and the more media you can stuff into it, the more effective and efficient your filtration is and the clearer/cleaner your water is.

Since it is outside the tank, you can conceal it under or at the rear of your aquarium stand. Canister filters are pressurized, which forces the water through its filter media rather than just letting it flow as other filters do. This makes them ideal for heavy loads.

How does a Canister filter work?

Most of the Canister filters force the water from bottom to top, channeling the water through a specially constructed cylindrical tube that minimizes dirty water bypass inside the filter until it reaches the canister’s bottom (using the power of gravity). Once it reaches the bottom, the water travels upwards through the several media trays or chambers, cleaning your water, and then exits into the outtake hose/tubes back into your planted aquarium. A few models work in reverse, forcing the water from top to bottom but still utilizes the force of gravity.

Is there any room for customizations with a Canister filter?

It can perform all three types of filtration extremely well, but for a planted aquarium, and as I mentioned in the previous article, we only need mechanical and biological filtrations. One of the main benefits of a Canister filter is the ability to customize the combinations of media you stuffed into it. By not using chemical filtration media, you can put more mechanical and biological media in its place.

A complete Canister filter package includes the Canister filter itself, with the built-in pump, a couple of trays for your media placements (some manufacturers employs chambers instead of trays), and sometimes more, depending on the volume, a siphon tube for intake, including the U-tube, a spray bar including the U-tube for outtake and hoses to route them in and out of your planted tank.

You can choose to use the included accessories (hoses, intake, and outtake) or customize them according to your needs. For example, in my Canister filter, I didn’t use the included spray bar and instead used a ‘duckbill’ so I can easily point the outtake to a direction (slanted downwards) that I want to effectively circulate the water, nutrients, and co2 bubbles across the whole tank. You can also use a Lily Pipe set. Whichever outtake you choose, it is important that it can provide the needed water surface agitation for aerating your water.

Some Canisters are modular that require an additional pump. The modular Canister filters are applicable when plumbed in line with other filtration types, such as a wet/dry trickle filter. If you know how a Canister filter works, you can even DIY your very own Canister filter if you are handy.

Are there any additional features that I should look out for?

Again, Canister filters work in the principle of suction. Some Canister filters have a priming button, which actually does the siphoning action by depressing it numerous times before turning on the filter. It is still manual, but the priming button brings convenience for us hobbyists instead of siphoning with your mouth. Some more advanced Canister filters have automatic self-priming with just a touch of a button.

One thing to note is that after you primed and started your Canister filter, there are still air bubbles/air pockets left inside your filter. You can remove them by gently rocking your filter from all sides until no bubbles are coming out anymore in your outtake. Watch all those air bubbles go.

Some Canister filter models have included UV light sterilizer as an additional filtration stage to kill/prevent bacterial/algae outbreak (such as cyanobacteria, green water, and algae spores). I know I said it could kill bacteria, but these UV lights inside these Canisters are designed to prevent you from killing your beneficial bacteria. The UV light is isolated from your biological media trays. These integrated UV lights’ effectivity depends on the offending bacteria and algae spores’ contact time that needs to be eradicated.

You can also use your in-line atomizer/reactor CO2 diffusers with the return hose of your Canister filter—less equipment inside your planted aquarium.

How do I maintain a Canister filter?

The frequency of maintenance with a Canister filter is far more apart, though. Please refer to the instructional manual of your specific Canister filter model. For example, my Canister’s routine cleaning is every 4 weeks, sometimes 5-6 weeks, due to scheduling conflicts. The longest was 2 months, and it’s not even too dirty and just had slightly reduced water flow.

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.

Are there any disadvantages when using a canister filter?

Canister filters have negative sides too. While one of the pros of a Canister filter is its larger volume capacity, it is more difficult to take apart for cleaning and maintenance. Be extra careful with those that have integrated UV light.
And since Canister filters are pressurized units, the rubber sealings may fail over time and needs to be lubricated or replaced. The amount of oxygen content in the water passing through the filter is reduced and needs additional help. There is no water-to-air contact in the biological media section. This means that the biological filtration is not as efficient as other filter types. Remember that your beneficial bacteria’s nitrification activities and population depend on the amount of oxygen and food available for them.

This is why I always mentioned in the previous articles to provide water surface agitation to aerate your water, even when injecting CO2. By having a planted aquarium, plants will respire oxygen, adding to your water’s oxygen content. Both of these can alleviate the con I mentioned above by aerating your water outside the Canister filter.

Remember also that your beneficial bacteria will not only colonize your biological media. They can grow anywhere in your planted aquarium, from your hardscape (rocks and driftwood), any submerged equipment, even on the inside glass of your tank, your soil, your plants, and some free-floating in water. Basically, everything submerged in your planted tank act as biological filtration media! 

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

Pros

  • A great filter for medium to large Planted Aquarium tanks
  • Highly customizable when it comes to choosing the most effective media, and you can squeeze a lot of it into the filter
  • Can provide 3 types of filtration – most importantly, mechanical and biological
  • Ideal for heavy loads – you can get away with overstocking without affecting your water parameters.
  • Concealable – at the back of your aquarium stand or inside the cabinet
  • Falls under the medium price range
  • Additional features from different brands such as UV light sterilizer, self-priming button, customizable when it comes to accessories, modular units can be plumbed inline with another filter.
  • Ability to use your in-line atomizer/reactor for more effective CO2 diffusion
  • The frequency of maintenance is far more apart than most of the other filters.
  • You can freely adjust the outtake/return’s direction – you may want to point the outtake upwards (underwater) to provide surface agitation (but you will outgas a lot of your CO2) vs. pointing it downwards to distribute the nutrients effectively; CO2 bubbles across the whole tank (water surface agitation will be provided by other means, such as DIY fans, or wavemakers)

Cons

  • If you have a Euro braced tank, a Canister filter’s U-pipes may not fit, or you have to DIY/customize to make it fit and secure.
  • Due to its size/volume/weight, it is more difficult to take apart for cleaning and maintenance. There is a high risk of dropping it or breaking the glass protecting the UV light. Be careful, always!
  • Canister filters are pressurized units. The rubber sealings may fail over time and need to be lubricated or replaced.
  • The amount of oxygen content in the water passing through the filter is reduced and needs additional help. There is no water-to-air contact in the biological media section. This means that the biological filtration is not as efficient as other filter types. This can be alleviated by having a planted aquarium in the first place and providing water surface agitation.
  • Another concern about the height of your tank (the height of your outtake U-pipe that hangs at the top of your tank) to the height at the top of the Canister. The further the water has to travel upwards, the more it will slow down, reducing your flow. And if the path is too high, the pump may not be able to overcome the force of gravity. So make sure that your planted aquarium is not too elevated with respect to the top of your Canister. For example, I have less than two feet of height from my Canister top to the top of my tank.

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.

Can We Do Filter Maintenance Along With Water Change?

Contrary to popular practice, some hobbyists will say that you cannot perform filter maintenance along with your water change schedule. This happened to me on some occasions due to scheduling conflicts.

While the most obvious disadvantage is you have many tasks to do, you can still do both subsequently in just under an hour. One advantage of this is you can use the old tank water extracted from your water change to rinse/clean your filter, filter media, and its accessories/parts, not compromising your good bacteria.

Just keep in mind that you keep your filter media wet and submerge using old tank water extracted during your water change. Wash and rinse your mechanical media (foams, filter floss, polyester pillow stuffings, etc.) with old tank water.

Clean your filter and hoses, in my case, my Canister filter with the same old tank water. Arrange your filter media back and quickly to avoid drying them out.

Let me share with you my routine when I stumbled with this situation:

1. Turn off your filter, surface skimmer, and pumps if there are any.

2. Perform your water siphoning according to how much percentage of water volume you want to change. While you are at it, vacuum your substrate as well. You may want to vacuum your mosses as well. You will be surprised how much debris, detritus, etc. are in your mosses (try to disturb the water around them, and you will see what I mean). They act as mechanical filters for small to medium particulates, dead organic matter, fish food, etc., in our planted aquariums.

3. Put the extracted water into pails or a big water basin.

4. I don’t fill up the tank yet with new water usually, but I turn on my aquarium fan to provide water surface agitation for my faunas. Depending on your filter type, this may take considerably more time compared to just a water change schedule. You can also choose to fill up your tank with new chlorine-free water. It is totally up to you.

5. Next, dismantle your filter. Put your biological filter media and submerged them in the extracted water earlier.

6. Wash, squeeze, and rinse your mechanical media (foams, filter floss, polyester pillow stuffings, etc.) with old tank water. Do this in a separate and smaller basin to avoid clouding the water in the big basin where your biological media are and avoid the nasties getting into your biological media.

7. Clean the inside walls of your filter and hoses with the same old tank water. For hoses, you can use hose brush cleaners.

8. Assemble your filter media back into the filter quickly to avoid drying them out.

9. In my case, I have a canister filter. I pour water from my tank, not from the water basin, to submerge my filter media. Set it aside for now. If you have a HOB filter, Overhead filter, sponge filter, or internal filter, etc., you can already set them up in the tank.

10. I fill my tank with new water. I remineralize it beforehand because I am using RO/DI water. Skip this if you’d fill up your tank in step # 4.

11. Next is to set up my Canister filter in its original position, insert the hoses, and then position the intake and outtake.

12. Turn on the filter, surface skimmer, and pumps if there’s any, and enjoy your hard work.

Conclusion

In this article, we 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.

Now we are getting into the bigger filters that you can use with your planted aquariums. Canister filters are pressurized which forces the water in rather than just letting it flow compared to other filters. This makes them ideal for heavy loads.

They are more powerful and bulkier than most other filters and thus, more suitable for medium to large planted tanks. There are many different designs and feature sets available commercially from different manufacturers. If you are a handyman, you can even DIY your very own Canister filter once you know how it works.

We also discussed how to maintain it and the frequency of maintenance for a Canister filter is far more apart. However, Canister filters have their own negative sides too that we also outlined.

Finally, regardless of your chosen filter, we discussed how you can maintain your filter without compromising your beneficial bacteria and if we can perform filter maintenance along with water change.

Closing Remarks

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

Next, we will be discussing the Rain Filters – the Trickle Filters.

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