# What filtration do you really need in a planted tank?



## elitejp

Hi, new to this forum and pretty new to keeping fish. So as with any new hobby I start researching the best I can so as to make this a good experience. What is confusing me (the most) is this filtration aspect for planted aquariums. Looking at some peoples posts on the internet it seems some people have 2 large external canister filters along with a separate biological filter for a 55g tank. Then I read somewhere where an individual stated that plants themselves act as one of the best bio filters there are. I guess what im getting at is what kind of filtration system do you need to buy or set up to maintain clear and healthy water?


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## Geomancer

Most people go excessively overboard with filtration. You only need a single filter sized appropriately for your tank.

And it's true, live plants are the best filters you can have. They will absorb and use ammonia better than the nitrifying bacteria. In fact, with enough plants they'll completely out compete the bacteria and you will always have 0 ppm ammonia, nitrite, and near zero nitrate. With enough plants you effectively have an 'instant' cycle and can add fish day 1.

Caution: You still need to perform a weekly water change to remove other untestable toxins (for example pheromones released by the fish) that can only be removed through water changes.

How many plants it takes to achieve that is highly variable on the types of plants and number of fish. Faster growing plants are better are using nutrients than slower growing plants.

In a fully planted aquarium the filter is purely used for mechanical filtration, removing particles in the water to keep it clear looking. In small tanks only a simple sponge filter is needed, in larger tanks most people go with a canister and only use pads/filter floss media.

Carbon is a no-no for planted tanks, it will remove nutrients for the plants. If you have a HOB filter, just remove the carbon from it. If the carbon can't be easily removed, just don't replace it. It will eventually run out and not absorb anything anymore. For the pad itself, it just needs rinsed in tank water during your weekly water changes and can be reused until it literally falls apart on you.


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## Byron

I concur with Geomancer. The only other issue is the fish; filtration needs to be geared to the fish, in terms of water movement and also true filtering. Plants handle the latter on their own, if the tank is balanced (fish/plant/water volume). For water flow, some fish need a stronger current, some need scarcely any at all, and some are happy in between. This is an important aspect of stocking a community tank, as "compatibility" includes water flow.

At the head of the Aquarium Plants section of the forum there is a series of article entitled "A Basic Approach to the Natural Planted Aquarim" that should explain this a bit more.

Byron.


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## elitejp

Awesome that has answered a few of the other questions Ive had as well. i think what I will do is add a canister filter to the tank. Im currently using a filtration system that sucks the water up over the tank to a cartridge that has some filter media in it (a type of fabric/sponge). The water flows through the cartridge from one side to the other and then down through a hole that drops the water into the tank. In all actuality the water has stayed pretty clear but the water dropping into the tank can be a bit noisy. And im sure the canister will do a better job than this filter in removing the debris. Plus ive read different things about water turbulence causing co2 depletion in the tank, but I also heard that only happens when your actually injecting co2. Otherwise it doesnt have an effect. Any thoughts on this topic? Currently I guess thats it for my questions. I know I have more but I forgot what they were. Thanks again for the help.


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## Geomancer

Yes, water disturbance on the surface will cause an exchange of gases, CO2 will leave and Oxygen will enter. This is true no mater if you use CO2 injection or not, just when using CO2 injection you would literally be wasting money buying CO2 just to have it escape the tank. Usually this exchange is necessary so the fish have plenty of oxygen to breath but in a planted tank, the plants them self provide more than enough oxygen.

The filter you are describing is what people call a HOB (Hang On Back), there is nothing wrong with them and lots of people use them. You can reduce the noise, and disturbance, by increasing your water level. Both my tanks have one, and I keep the water just over the lip of the outflow so it isn't splashing into the tank. They are a good inexpensive filter for 55g and under. Sponges are even cheaper, but if you already have a HOB there is no _need_ to buy something different.

I stress the word need above, if a canister is more appealing by all means get one. Just get one sized for your tank, too much flow has a negative effect on a lot of fish because they have to expend a great deal of energy just to stay still which will cause them stress. Canisters offer the benefit of a wide variety of filter media available for them. You can combine both course pads and fine pads/filter floss to catch both big and small particles. You can also add 'bio media' if needed, but isn't if a fully planted tank.


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## elitejp

What I did with one tank was to take a black sponge filter and shove part of it into the hole where the water leaks out and let the rest of it hang into the water. My thoughts are that the water passing through the hole directly into the sponge and then into the tank would stop any water turbulence and would also make a great home for beneficial bacteria. Im not sure if this is correct but to me it sounds like a good idea. Similar to the principle of the bio wheel. Plenty of air and water to help those little guys grow. I suppose as long as the water looks clean and the plants are doing their job then I will hold off on buying anything bigger. The other thing that has me concerned about canisters is that I would like to have discus in the tank and I dont know if the running 150-250g/h of water pressure (50g tank multiplied by 3 to 5 for canister filtration) through the tank would stress the fish too much.


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## AbbeysDad

Welcome elitejp,

I agree that filtration is often misunderstood. Over and over I see hobbyists echo that you need 4x to 10x the tank size in GPH water flow. But good filtration is not really about water flow volume, but about filtering through fine media and of course having some stable bio-media.
Now canister filters are the latest, greatest things to the hobby. But, they're pretty expensive and often not suited to smaller tanks, say less than 55g. I also have a bit of a problem with HOB cartridge filters since eventually the cartridge is replaced and the beneficial bacteria gets tossed like throwing the baby out with the bath water. I even think the bio-wheel is a nifty concept, but highly over-rated. For a HOB, I quite like the AquaClear design and I also like the look of the Fluval 'C' series (also made by Hagen) that compartmentalizes the filter chambers AND has a novel wet/dry chamber for bio-media - very new age for a HOB.

Now, we need a better definition for "I have a planted tank". Some folks say this and when you see the picture, it's a couple of plants in an otherwise stark aquascape, with questionable lighting, substrate and fertilization. We'd agree, not really a planted tank. There really needs to be a lot of plants to even handle a modest bio-load with respect to an impact on filtration.
Obviously, there are folks here that have heavily planted tanks with little/no external filtration (e.g. a simple air driven sponge filter) - but perhaps more exception than rule.

Anyway, the bottom line is that you can get a canister filter. But if your water is currently clear, suggesting that your existing HOB is doing a good job, just maybe your money is better spent elsewhere?
Also your very best filtration is a weekly 50% water change since nothing beats FRESH WATER.


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## Byron

Some good advice from both members in the last 2/3 posts.

For a 55g 4-foot tank with discus and plants, I would get a good canister rated for that sized tank. My first choice would be Eheim, second Rena, third Fluval [and they are in that order from most expensive to least expensive]. We can go further into this if you ask, but most of us have commented in other threads on this subject too.

Now some comments on water flow and disturbance and all that. For years I have read how surface disturbance causes an increase in the gas exchange and oxygen enters the water and CO2 leaves the water. Knowledgeable botanists, microbiologists and planted tank authors have all said as much. Things are however changing. I am now seeing more and more the opposite view, that disturbance draws CO2 into the water. I have some discussions on this elsewhere with knowledgeable folks, so we'll see where I end up coming down on this issue.

But one thing is certain, and that is the effect of water movement on fish. Leaving surface disturbance aside, I would not get a flow through the aquarium with plants and fish like discus that was strong enough to make the plants sway. In my tanks, my Eheim and Rena canisters are ideal, and I have the models recommended for the various tank sizes. I can set them up to give me a fairly strong current at one end (as in my 115g for fish that absolutely must have this) or I can use the spray bar to create a steady flow throughout the tank that cannot be visibly noticed. The spray bar can be adjusted to increase or reduce surface disturbance. So we have the best of all worlds here. Which is why I recommend a good canister for 4-foot and larger tanks with plants and forest fish.

Byron.


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