Types of Planted Aquarium Filters – Internal Filters

by Apr 11, 20210 comments

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.

Table of Contents

Functions of Planted Aquarium Filter
Types of Planted Aquarium Filters
Internal Filters
How does an Internal filter work?
How do I maintain an Internal filter?
Are there any disadvantages when using an internal filter?
Pros
Cons
Stressing This Out Again!
Can We Do Filter Maintenance Along With Water Change?
Conclusion
Closing Remarks

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.
Nature's Natural Filtration

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

Internal Filters

An internal filter is placed inside the tank and is totally submerged in water from the name itself. They were the first aquarium filters available for home aquariums. But with the dawn of aquascaping, these filters have lost their acclaim, but they still have their uses in planted aquariums.

Corner Filter by Gray Paulino Philippines

Corner Filter by Gray Paulino Philippines

Using Corner Filter Aquascaped by Gray Paulino Philippines

Using Corner Filter Aquascaped by Gray Paulino Philippines

How does an Internal filter work?

They come in many different styles and are solely placed in the aquarium either in the substrate or mounted to one side or corner, using suction cups. Some of the common internal filters are the sponge filter and the corner box filter, in which an airline tubing is attached to the inline of the filter and will be driven by an air pump outside the aquarium. You can customize the media you put into a corner box filter compared to only a sponge filter.

The external air pump will pump air (duh!) at the intake, to the bottom of the filter, move through a separate outtake tube, then dissipates to the surface of the water. The air bubbles’ action moves water into the filter media (sponge for sponge models or several mechanical and biological media for corner box filters), which permits it to provide mechanical filtration by trapping debris, detritus, etc. and be able to grow the beneficial bacteria to establish your tank (biological filtration).

That is why another form of internal filter is invented to solve sponge or corner filters’ disadvantages. There are also internal filters that don’t need to be driven by an air pump. They have a built-in water pump to suck in water, move the water upwards through layers of mechanical and biological filter media, then an outtake (fixed – horizontal or adjustable) to return the filtered/clean water. They can be placed anywhere inside the tank (using suction cups), wherever direction you want the outtake to point to. They are more effective in performing mechanical and biological filtrations due to higher turnover rates.

Using an Internal Filter Aquascaped by Melchin Origenes Tapan Philippines

Using an Internal Filter Aquascaped by Melchin Origenes Tapan Philippines

Using a Sponge Filter Aquascaped by Andrian Jutba Philippines

Using a Sponge Filter Aquascaped by Andrian Jutba Philippines

Using a Sponge Filter by Aldrin Solano Gacos Philippines

Using a Sponge Filter Aquascaped by Aldrin Solano Gacos Philippines

Internal filters are best suited for small tanks, from nano tanks, up to 10-15 gallons but usually no more than that. Using a single sponge or corner box filter in 15 gallons is already stretching it. The only reason you can use them for medium to large tanks is just for supplementary filtration. For example, if your main filter is a Canister filter or a HOB and its flow won’t reach every part of your tank, then you can use internal filters strategically mounted in your tank. This ensures even distribution of clean water, nutrients, co2, etc., across the whole tank.

How do I maintain an Internal filter?

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 your sponge filter 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.

Internal Filter and Submersible Pump

An Internal filter and Mini Submersible Pump in one – with some kind of Grating and a small sponge inside to Trap Free-Floating Solids. It helps with the distribution of CO2 and nutrients across the whole tank. I have 4 of these deployed in strategic locations.

Are there any disadvantages when using an internal filter?

As one of the oldest types of filters, it is cheap, but the mechanical and biological filtration in air-driven internal filters is limited due to the low flow (meager turn-over rate), low oxygen, and water volume moved into the filter. This made way for the internal filters with built-in pumps to perform effective mechanical and biological filtration for small to medium tanks. A standalone surface skimmer works in the same principle, in which it sucks water down using a built-in pump. It traps surface oils, dust, and proteins accumulating from your water surface.

My Standalone Surface Skimmer

My Standalone Surface Skimmer

Using two Sponge Filters Aquascaped by Christian Cortes Philippines

Using two Sponge Filters Aquascaped by Christian Cortes Philippines

They have limited use in aquascaping. They can ruin the look of an otherwise pleasant aquascape since they are placed inside the tank. You can hide them behind your plants and hardscape, but they still take up significant space. These filters’ particular uses are in plant grow-out tanks, non-display planted tanks, breeding planted tanks or hospital tanks. Some hobbyists have grow-out tanks, wherein they grow plants to sell later or be transferred to their main tank and don’t want to spend more on expensive filters.

They can also be used in breeding planted tanks. Because there are no moving parts, newly hatched fish or shrimp fry won’t be sucked into the filter, resulting in lower mortality rates. Some hobbyists also employ a separate hospital tank kept running to treat whenever they have sick fish. Again, these filters are very inexpensive but have limited applications with planted aquariums.

Using an Internal Filter - Aquascaped by Khristian Ross Santos Philippines

Using an Internal Filter – Aquascaped by Khristian Ross Santos Philippines

Using Internal Filter and x2 HOBs by Jeremy Navarro Philippines

Using Internal Filter and x2 HOBs by Jeremy Navarro Philippines

To summarize, here are the pros and cons of an internal filter:

Pros

  • inexpensive – in which they can be bought in bulk for your breeding tanks, grow-out tanks, or hospital tanks, etc.
  • can be effective on nano to small tanks and can also be effective as a supplementary filtration for medium to large tanks
  • doesn’t have moving parts (low turn-over rates) – gentle for your fry on breeding tanks or more delicate faunas
Using a Sponge Filter Aquascaped by Hen Cong Jon Philippines

Using an Internal Filter Aquascaped by Hen Cong Jon Philippines

Cons

  • limited mechanical and biological filtration due to meager turn-over rates – no horizontal flow to distribute filtered water
  • limited on how much media you can stuff into them
  • since the mechanical and biological filtration happens on the same surface (sponge filters), the sponge can get clogged by debris quickly, choking your beneficial bacteria and prevents them from doing their job well. This means more frequent water change/maintenance/cleaning
  • takes up significant space inside the tank
  • limited use in planted aquariums
  • depending on your lighting height, the continuous air bubbles dissipating on the water surface. Thus, the continuous water splashing may damage your lighting, most especially if it has no diffuser or waterproofing.
Using a Corner Filter Aquascaped by Deem Venson Philippines

Using a Corner Filter Aquascaped by Deem Venson Philippines

Using a Corner Filter Aquascaped by Randel Hilario Philippines

Using a Corner Filter Aquascaped by Randel Hilario Philippines

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.

Using an Internal Filter Aquascaped by Augustus Alejandro Zenit Philippines

Using an Internal Filter Aquascaped by Augustus Alejandro Zenit Philippines

Using Internal Filter Aquascaped by Martin Ladioray Philippines

Using Internal Filter Aquascaped by Martin Ladioray Philippines

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.

Front View During Water Change 25 %

Front View During Water Change After Siphoning 25 %

Top View During Water Change 25 %

Top View During Water Change After Siphoning 25 %

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.

Siphoning my Substrate and Carpet Plants

Siphoning my Substrate and Carpet Plants

Trimming my Mosses while siphoning them

Trimming my Mosses while siphoning them

Extracted water from a Water Change into a Basin

Extracted water from a Water Change into a 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.

Keeping my Biological media wet using old tank water during water change

Keeping my Mechanical and Biological media wet using old tank water during a water change

My Filter Tubings starting to get dirty

My Filter Tubings starting to get dirty

My Tube Cleaning Brush

My Tube Cleaning Brush to clean my filter hoses

After cleaning the inside walls of my Canister Filter

After cleaning the inside walls of my Canister Filter

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.

Assembling My Canister Filter and its Media Trays

Assembling My Canister Filter and its Media Trays

After Positioning My Canister Filter and its Hoses

After Positioning My Canister Filter and its Hoses

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.

Our second type of filter is the Internal filter. Literally, they are installed inside your planted aquarium which comes with a lot of disadvantages but they still have some use despite the advent of aquascaping.

We also discussed how they work and their many different styles. The most common forms are the sponge filter and the corner box filter. There is also another form that has a built-in water pump to suck water into a sponge and/or several layers of biological media. This form of internal filtration solved most of the cons of air-driven internal filters.

With planted aquariums, there are many cons for this filter but they still have their uses because it is cheap and can be ordered in bulk for your breeding tanks, grow-out tanks, or hospital tanks.

Closing Remarks

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

Next, we will be discussing the Pressurized Filters – the Canister Filters.

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