Canister filters not really needed?

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Is canister filtration filtration useless in a planted tank?

  • Yes

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  • No

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mcompagno

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I have an interesting revelation to share. I have a 37 gallon tank that has large anubias and ludwigia dark red along with a small piece of driftwood. I have been running an Eheim Ecco Pro canister filter along with an air powered sponge filter and small powerhead set on the lowest setting for additional water circulation. The tank is heavily stocked. The tank has been up for several years and the fish and plants have been doing great.

A few days ago my tank sprung a leak about 2/3 up from the bottom, so I had to lower the water and remove the canister, which had seachem matrix in it for bio media. I was very worried that I would have a severe ammonia spike.

The interesting thing is that my readings have been fine and my nitrate has actually gone down. My fish seem happier than ever with the altered configuration.

I am wondering if canister filtration is not really needed in planted aquariums? It seems the canister was totally not needed? Very surprised at this outcome.
 
Welcome to TFF. :hi:

There is a lot of misunderstaning in this hobby about filtration. The short answer to your question is yes and no. It depends upon the specifics of the aquarium, and each aquarium can be quite different biologically, even if we use the same substrate, light, fish load, feeding, plants, etc. I have 8 tanks running in my fish room, and each is certainly unique biologically.

It is possible to have a healthy planted tank with no filter at all. I've done it, as have others. You must have a specific balance between fish and plants for this to work. As soon as you tip the balance--by too many or too large or the wrong combination of fish, too few plants, too slow-growing plants, too much fish food, insufficient water changes--you can have a disaster overnight.

The same thing can happen with a filter too of course, but provided the tank is biologically in balance to begin with, the filter is more of a safe-guard. There is a real myth in the hobby that the larger the filter or the more filters, the better, but this is completely false. The fact is that too much filtration (meaning, with the use of filter equipment) can be detrimental, not beneficial.

I have filters in all my tanks, and all have live plants, and all including floating plants. These floaters are really the key, as they do more to "filter" the water because they are fast growing, and they are fast growing because they have brighter light (being right under the tank lights) and can assimilate CO2 from the air as opposed to solely from the water, and this is about four times faster for the plant. So there is a real benefit to floating plants. Some call them ammonia sinks, because they can assimilate a lot of ammonia/ammonium. Plants take up the ammonia/ammonium faster than the Nitrosomonas sp. bacteria, so this is another reason why you can do without filters--again providing things are intially in balance.

I also have a filter in all my tanks now; the smaller (10g, 20g, 29g, 33g and 40g) each have a dual sponge filter. The two larger tanks (70g, 90g) have Eheim Pro II canisters. The prime job of all of these in my tanks is one of water cirtculation and clarity; mechanical filtration circulates the water and removes particulate matter. Obviously, all these filters will function as biological filtration too, but I do not rely on them for this. And it is true that in planted tanks, you do not want to be overdoing the biological filtration because the filter is then competing with the plants.

Another aspect of this is that there will be more bacteria elsewhere in the aquarium than in the filter, and primarily in the substrate. The substrate is the most important part of a healthy aquarium. There are many species of bacteria besides the nitrifiers that are important, and all these can be found in a healthy substrate.

So to try and provide a summary answer to your question, I would say a mechanical filter that does not overdo the water movement is advantageous, but biological filtration is not. The latter will occur, but should not be "encouraged."

On your readings, that is what I would expect. As I noted above, plants take up ammonia/ammonium as their preferred source of nitrogen, and when this is insufficient (in balance with other nutrients and light) they will turn to nitrate (possibly nitrite too, though the evidence for this is still scanty). By removing the bacterial filtration that occurs in the filter, you are providing more nutrients for the plants. However, Anubias is slow-growing, so its capacity for helping here is much more limited than is that of the stem plant Ludwigia. Floating plants would significantly increase the safety zone, so to speak. I don't know the fish load (your "heavily stocked" may not be my interpretation of the term) or feeding, but I would assume they are not maxed out, though it may still be early days. But the establishment of the biological system for the several years mentioned likely means you have a good substrate filter bed. In a new tank, something like this might not work at all.

Byron.
 
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I have never considered my 180 litre tank to be well planted but I have been comparing it to the planted tanks in other members' photos. I have java fern, several species of anubias, bolbitis, hornwort and water sprite. As you can see, apart from the floating water sprite, the plants are all species that can be attached to decor (lots of wood in my case) and I have none planted in the substrate.
My tank is also over stocked due in part to having to close a tank and move the fish into my 180 litre.

A few weeks ago I turned the filter off for a few minutes one evening and forgot to turn it back on. I realised it was off 24 hours later. Naturally I panicked and got out the test kit to discover zero ammonia and zero nitrite.

After reading the above, I now realise why.

And also why I have to remove handfuls of water sprite on a regular basis!
 
My planted tank likes to go to zero nitrate simply because the plants absorb all the nitrogen in the tank. Several times i have had an animal die while I was on vacation. When I got back there was no evidence of ammonia, nitrite or nitrate. Recently i had a couple of nitrite snails die. I decided to not do anything and just monitored things. I have an a hanna nitrate meter capable of reading 0.01ppm of ammonia. it also showed zero ammonia the entire time. Nitrite also showed zero. I had added some nitrate fertilizer earlier and so I was reading nitrate but that level did go down. It never went up. TDS (total dissolved solids) readings also stayed stable at 220ppm

In order for the above happen you ned to have sufficient nutrients in the water (mainly trace nutrients). If your plants are not growing well you might no see nitrate drop.
 
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The biology in a tank is somewhat of a mystery. Hobbyists have been 'conditioned' to think that beneficial bacteria lives (only) in the filter. Just as they've been conditioned to believe they need special bio-media and 4 - 10x GPH filter water flow for good filtration. Some even believe they must 'over filter' (more water flow) for higher quality water.
Frankly, these are actually quite wrong. As Byron notes, far more beneficial bacteria exists in a healthy substrate and on other hard surfaces than would ever be found in a filter. Additionally, there is (again as Byron noted) a vast array of various aerobic and anaerobic bacteria in the substrate that assist in maintaining a healthy aquarium.
I have long questioned the idea that greater water flow through a filter (or filters) means better/more filtration. After all, good filtration is how well the water is filtered, not how much water is pushed through a filter!
After many years in the hobby I also came to question the marketing hype regarding bio-media and have learned that simple sponge is every bit as good or better as a platform for BB.
In a heavily planted tank, plants do a lot of filtration as they absorb nutrients that would otherwise be pollutants. In some ways, this is a level beyond mechanical or what we think of as bio-filtration. But this requires somewhat fast growing plants and/or plants that require/use sufficient nutrients for tank balance.
In a 37 gallon planted tank it would seem to me that a power filter, a sponge filter, and a powerhead combined is unnecessary over kill. You want good mechanical filtration and sufficient water circulation, but excess should be avoided. (just my dime).
 

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