The tank is filtered by an Eheim 2260 canister filter with Eheim diffusor. I've been drooling over the 2260 ever since I was a kid. Now I finally got one, and the thing is all I ever dreamed about!

The Eheim classic series of filters has been around virtually unchanged since the 1970s. That means they lack any modern gizmos such as self priming and so on. In my humble opinion there simply is no better filter money can buy! They are super quiet, very efficient, and they last forever. I have had Eheim classic series filter run on tanks for 20 years and more without a hitch. I bought my first 2213 in 1977 when I was 10 years old. Today I am running a 2217 on a 75G and this 2260.

Priming Eheim Classic Series Filters

Some people claim Eheim classic series filters are hard to prime, but I have never found that myself. The problem with these filters not starting up after a service is invariably air in the pump-head. The pump cannot expel this air by itself, so you have to get it out, or the pump is stuck. Expelling the air is very easy to do if you are using Eheim's double-tap-quick-release in the return pipe from your filter to the pump. If you are using a a Hydor external thermal heater, like I am doing, the quick-release goes between the filter and the heater. While we are at it, you also want to put a double-tap-quick-release in the intake pipe of your filter, so you can remove the filter easily from the tank for maintenance. Anyhow, here is how I start up my Eheim canister series filters after maintenance:

1. Put all the media back in the filter and close it up.
2. Connect the filter to it's intake via the corresponding double-tap-quick-release on the lower end of the filter, and open both of the taps on the quick-release.
3. Do not connect the filter to the return pipe to the tank, but hold hose that's connected to the outlet of the filter over an empty bucket and open that tap. If there was still water in the filter intake line from the tank down to the double-tap-quick-release near the filter intake, the siphon should start automatically filling the filter with water. If not, you need to give the return pipe a quick suck with your mouth to start the siphon.
4. Wait until the filter has filled all the way with water, maybe tilting it a little at the end to expel all the air in the filter. You want water to run clearly through the filter into the bucket without bubbles. I will even plug in the filter shortly to remove air from the pump around the impeller.
5. Unplug the filter, close the tap on the filter outlet, and connect the filter to the return pipe via the corresponding double-tap-quick-release at the upper end of the filter.
6. Open the return line and plug in the filter.
7. DONE!

In 99 cases out of 100 all air will have come out of the filter this way, and it will start without a hitch. On the rare occasion that it does not, you simply have to disconnect the double-tap-quick-release at the filter outlet, and let some more water run into your bucket until there is only water in the filter and no air. If you follow this procedure, you will find priming Eheim classic series filters a breeze, and you can save hundreds of dollars on what a similar filter with self priming feature would cost.

Filter media and filter maintenance

I am a great fan of Eheim filters, but I don't use their media. I am sure they are good, but IMHO they are way overpriced. I use filter floss as media - and ONLY filter floss. I find it's cheap and does an excellent job for both, mechanical and biological filtration. I have been using it in Eheim classic series filters since 1977 when I was at the tender age of 10, and am currently running it in the 2260 on this 125G as well as a 2217 on my 75G Geophagus setup. I have tried other media time and time again, but I have never found anything that works as well as filter floss and is anywhere near as cheap.

I have used filter floss dedicated for aquarium purposes bought at the LFS and online retailers such as Big Al's Online, but my favorite material is Fairfield Poly-Fil^® Premium Polyester Fiber. I have bought it in 16oz (1 pound) bags from Walmart, but last time I stocked up Amazon had the best deal at $45.20 for the 10 pound box. For the 2260 on my 125G and the 2217 on my 75G, 10 pound are going to last many years.

With using filter floss in a canister there is some skill involved in packing it just right. If you are packing it too densely, the filter can clog up fairly quickly. It is pretty obious though if the flow is reduced. You can see it with a spray bar, but possibly even more so with a diffusor. You also don't want to have too little floss in the filter, otherwise the water will bypass the floss and your filtration is less than ideal. You can see if that has happened when you open the filter, because there will be brown channels through the floss where all the water has run. With a bit of practice you quickly get the hang of how much filter floss to put in a filter and you can have little to now bypass and no clogging up over several months.

I am one of those people who think canister filters ideally should not be opened more than once every 3-4 months so as not to disturb the bacteria doing their job. I think that approach might be more popular in my native Germany than in the US, and although I can no longer find the source, I believe Eheim used to recommend it on their web site too. Because I am lazy I tend to shoot for filter maintenance twice a year, which worked perfectly for me with a 2217 on a 29G tank. In other words, for that to work you need a big enough filter for your tank, and even then there will be a good amount of crud in the filter when you open it. The bottom layers of floss in my filters will get brown very quickly, and the brown layer will get thicker and thicker as time goes by. If I open the filter and all the floss is brown with dirt lying right under the pump head, I know that I left it for a bit too long. If there is still a good layer of fairly light or white floss on top, I know that I could have gone a bit longer. After doing this for a few times with a given filter, tank and stocking list, you know what to shoot for - and if the required maintenance intervals are shorter than you like, you can always buy a larger filter!

What about all that dirt that remains inside the filter for for so long - won't that harm my fish? I believe the 'bio reactor' that forms inside a well working canister filter is enormously effective, meaning the bacteria will break down any organic material that arrive inside the filter within hours. If the decomposition took longer, you would find half decayed leafs and other still recognizable organic material in the filter when you open it, and I never do! In fact, I once put some pot scrubbers in the filter and made a mistake in not using the nylon ones everyone likes so much but spongy ones that turned out to be biodegradable. They were virtually gone within a few days, and that's a huge amount of organic material in the filter - orders of magnitude larger than what it would usually see! The main products of the bio reaction in the filter are carbon dioxide and nitrate. The carbon dioxide will serve to feed your plants or gas out into the air. The nitrate will be removed through water changes - which is why performing regular water changes is so important! A minor percentage of the products is solid. This solid material left in the filter will not decay, since it already is the product of the decay of organic material, and as such is as inert as a rock or soil - which is basically what it is. In fact, its surface will be settled by bacteria and it becomes part of your bio filtration media. I have very successfully used this material from a well running filter to seed a new tank with beneficial bacteria, and it is probably more effective than most products meant to kick-start cycling of a tank that you can buy in a store. If you remove this inert material from your filter it in a day or in a month is irrelevant, as long as there is not so much of it that it blocks up the flow through your filter and limits its effectiveness in that way.

Now, when the time comes to actually clean the filter, I discard 100% of the floss. This is mostly because I am lazy, and it allows me to extend the times between filter cleanings. I can get away with this, because my tanks have a lot of natural decoration materials in there - wood, rocks, and life plants. These items also provide huge areas for beneficial bacteria to settle on - think of all the nooks and crannies in wood and rocks, a clump of Java moss, or the tangled roots of a big Java fern. I never clean the wood or rocks in my tanks, and I am sure quite a few people would find my tanks quite dirty with all the algae and moss growing over things, but I like it that way, and I like to think my fish do too. For bacteria there is no difference between living inside the tank or inside the filter! So even when I throw out all of my filter material, I make only a small dent in the bio filtration capacity of my tank. Of course if somebody had a bare bottom tank with only some plastic decorations, they should take care to replace only 2/3 of the floss at a time at the most and keep the rest.

Noise

Arguably, Eheim Classic Series Canisters are the quietest aquarium filters available on the market to date. That not withstanding, the faint pump noise they still emit can be further reduced by placing the filter inside a cabinet, and lining the inside of the cabinet with a suitable insulation material. Large rolls (sufficient for the lining of at least two aquarium cabinets), of the building insulation material I used can be bough at hardware stores like Lowes or Home Depot for around $10.

I also found that using the cover for the pump head that is included with the Eheim 2260 lead to a very faint rattling noise. Since the cover for the pump head serves no purpose that I could discern, other than possibly making the filter look at little sleeker when you see it in the store, I put the rattling cover into permanent storage well away from the filter!

Snail Proofing an Eheim 2260

Eheim 2260 pump inlet blocked by three pesky sails.

I've touted the Eheim 2260 as the best aquarium filter money can buy, and I stand by that verdict. However, the Eheim 2260 has one weakness that I am aware of - it quite easily clogs up due to snails. This happens right at the pump intake, meaning the snail has to make it's way from the tank into the filter itself and then travel all the way through the filter media from the intake at the bottom of the filter to the top where the pump is. Also, one snail will slow down flow, but it actually takes three snails of the exact right size to block the filter completely. The photo above proves that exactly this can happen. The night before I took the filter apart to take that photo, the filter had been running just fine as far as I could see, but by the next morning the water flow had become insufficient to drive the Eheim diffusor, meaning aeration had stopped and the tank was heading for a disaster.

Usually you will see the filter slow down by one or two snails fitting into the critical spots, and you can take action before bad things happen, but the big worry for me always was, what if this happens while I am away for a few days? I thought about this long and hard, and finally came up with a simple yet elegant solution in form of Poret^® Filter Foam. I simply cut a piece of Poret^® Filter Foam to size using a kitchen knife, and fitted it into the pump inlet in the lid of the Eheim 2260. The filter foam does not significantly restrict flow, but securely prevents snails from leaving the filter chamber and reaching the critical area before the pump where they can block the flow through the filter. I happened to have Poret^® Filter Foam available, because I use it as filter medium in the sumps of my 240G tank. It is available from Swiss Tropicals, and useful for many aquarium projects. In the absence of Poret^®, you could also use a piece of an old sponge filter, but make sure the material is not too fine or else it might block your filter.

Eheim 2260 filter outlet the bottom of the filter lid. Left: original. Right: secured against snails by Poret^® Filter Foam.

Canister filters and UGJ Systems

In my 240G tank, I use an Under Gravel Jet (UGJ) system to prevent debris from settling on the substrate until it has found its way in the filter intake. This greatly reduces the need for gravel vacuuming. A canister filters can certainly be used to drive an UGJ system. I had an Eheim 2217 drive an UGJ system on a 29G tank for years without any trouble. Many people told me the UGJ system would put added strain on the pump and wear it out, but with magnetic drive pumps like they are used in most common canister filters that is really not the case, and my experiment has proven that.

There is a bit of a difference, however, between using an UGJ system with a canister filter, and using one with a sump system. With a canister, the intake of the filter is usually submerged, whereas most sump systems draw water exclusively from the surface of the tank. Any UGJ system will have a much easier time driving debris into a submerged filter intake, while transporting debris over the rim of an overflow box into a sump can be a real challenge. Despite this problem, in my experience UGJ system are at their best when used with a sump, because the drainpipe will automatically provide excellent aeration of the water. This means that there is no disadvantage in having a submerged filtration outlet in form of an UGJ system. A canister with submerged outlet, on the other hand, contributes virtually nothing to aeration, and if you choose to use your canister to drive an UGJ system, you will have to provide for sufficient aeration in another way, for example by use of a power head with Venturi feature or an air pump with a bubble stone.

Since I try to keep any visible technology out of my tanks, I find didn't want to use either of these, and decided not to use an UGJ system in this tank. Luckily I found another great solution to prevent debris from settling on the substrate - in form of an Eheim diffusor.