Filtration in the Planted Aquarium

Planted Aquariums are ones that rely on a lush assortment of live aquarium plants for aesthetic appeal. Tropical fish populations in such aquariums tend to be smaller than in regular freshwater fish tanks. In planted aquariums, these fish provide a focal point for the overarching scene, for the diverse array of greenery.

Despite the low fish population, efficient filtration in the planted aquarium is an absolute must. As with regular freshwater fish tanks, I strongly recommend the use of canister filters (packed with biological filtration media) in planted aquariums.

In this Aquarium Filtration article, therefore, I’ll discuss the proper use of canister filters in the planted aquarium.

Defeating Algae: Make Planted Aquarium Care Easy

The use of efficient filtration methods in the planted fish tank is vital to for the well-being of your plants!

In a regular freshwater aquarium, algae growth is not a big problem because you can easily wipe the clingy green buildup off of tank walls and aquarium decorations.

Algae growth on plant leaves, however, not only looks unattractive, but it also may cause irreparable damage to your live aquarium plants. Algae will obstruct the penetration of life-sustaining light into the plant leaves, and it’ll significantly limit gas and nutrient exchange between the plants and the surrounding water. Unfortunately, wiping and/or scraping algae off of leaves is not good solution, for doing so will damage the plants.

For the above reasons it is critical that you maintain optimum water conditions. You can do so by using clean RO water, keeping from overstocking your tank with fish, and not overfeeding the fish you have. In addition to keeping the water clean, you should also consider the benefits of promoting strong water circulation. Doing so will prevent many problem algae species from growing on your plant leaves.

Water Flow in the Planted Aquarium

Unlike tropical fish, aquarium plants cannot move about the fish tank to find nutrition. Live plants can only utilize the fertilizers and CO2 (for those of you who use CO2 reactors) when these substances make physical contact with the plant leaves (common sense, right?).

That’s why sufficient water flow is essential for success with live aquarium plants. At the same time, you don’t want to create excessively turbulent tank conditions. Strong currents will rip aquarium plants right out of the substrate!

So, what is the right amount of water flow?

Well, if you’re like most freshwater aquarists, you probably rely on your filter to provide most, if not all, of the water movement in your fish tank. Since the filter’s water pump is the mechanism that actually moves the water, you can choose the right filter for your planted aquarium by taking a look at the flow-rate of the filter pump.

World renowned aquarist, Takashi Amano, suggests the following filter pump flow-rates for planted fish tanks: “6 liters (11/2 gallons) per minute flow for 60- to 180-liter (15- to 45-gallon) aquariums, 20 liters (5 gallons) per minute for 300- to 6000liter (45- to 75-gallon) aquariums, and 30 liters (8 gallons) per minute for 300- to 600-liter (75- to 150-gallon) aquariums” (Amano 95).

Although the above flow-rates may seem high, keep in mind that the force of the water leaving the filter is quickly defused as the out-flowing water encounters resistance as it makes its way into the aquarium. To put it more simply, water movement, while strong at the base of the filter out-take, is subtle in the rest of the aquarium.

Nevertheless, the water flowing out of the filter may damage plants located directly in front of the filter out-take. In fact, Amano suggests positioning the filter out-take tube towards the front of the aquarium where shorter foreground plants grow (96). These low-growing plants are not affected by strong currents, and they don’t obstruct water movement.

As you can see, filtration in the planted aquarium takes some consideration. Still, five minutes of planning beats five years of looking at a mediocre aquarium! It’s well worth the extra bit of effort.

Bibliography:

Amano, Takashi. “Filtration in the Nature Aquarium.” Tropical Fish Hobbyist, January 2007, 94-96.

Discussion

2 people commented on "Filtration in the Planted Aquarium"
Feel free to join the conversation and leave a comment as well.

  • Rohan says:

    Thanks for the info! I’m setting up a 410 litre S.E.Asian biotype Barbs tank which will be about 2/3 planted with Java fern, Crypts, Vallisneria, Apogneton, Rotala and some small lily-pads. I have an Atman CF1200 canister filter rated at 1700 lires an hour and a Bouyu fluidized bed filter with Atman pump @ 600 l/h. Now I’m confident that with the outflows pointing away from taller plants at back it will probably be ok but I can always turn it down with a valve. Now I also understand it’s mainly a matter of the plants just staying rooted in place. I’ll probably use Seachem Flourish-excell organic carbons without CO2 to help with establishing things.

    Cheers!

    Rohan.

  • admin says:

    Hi Rohan,

    Thanks for posting. I love biotope aquariums, and it sounds like you have an excellent setup in mind.

    Yes, initially plants should not get too much water movement (you don’t want to expose them to direct water flow from the outtake) in order to prevent uprooting, as you had mentioned. However, once the plants establish their root systems, it’ll be hard to pull them out by hand (aquarium plants will be firmly rooted in the substrate), and too much water flow will not be an issue!

    Of course, more delicate plants, such as Rotala and Lilies, shouldn’t be placed directly in the line of the filter outtake. Also, Java Fern (I’m assuming you’ll be attaching it to driftwood or rock, as opposed to planting it in the substrate) tends to take a while to firmly attach (especially to the relatively smooth surface of driftwood), and too much water flow may be an issue for the first two months or so.

    All that said, higher rates of water flow will prevent sediments and detritus from settling on plant leaves, thus discouraging algae growth.

    Finally, Flourish-excell is a good substitute for CO2 injection. I use the liquid additive in my planted tank and am pretty happy with the results.

    Good luck with your new aquarium setup, Rohan. Feel free to post any more questions you may have, and do let me know how your tank is coming along :)

    Best,
    Luke



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