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Now, I’ve been using these filters for several years now. Generally, users who write reviews of filters do so at the initial purchase and set-up stage. While this is fine, I think that the difference between a good filter and bad filter is above all how it performs over time. Ideally, a long, long time – in which you don’t properly clean it, or maintain it, or replace the parts, or use the correct media, or look after it at all. Happily, I’ve been maintaining these very conditions (purely for scientific purposes, of course) for quite a while now . In addition, I’ve only ever acquired second-hand versions that have already taken some abuse, so I’ve learnt to fix most of the problems associated with them.
So on to the review. The first and last thing that needs to be said about Classics is that they are very reliable. There are three reasons for this.
Eheims are famously made in Germany. I understand that the canister itself is now made in China for the Classic series, but since that’s really just a transparent green bucket I don’t view that as overly important. The reason why things made in Germany are good is not because of their proximity to all that delicious sausage and senf, it’s because German quality control and manufacturing standards are generally insane. I mean, in a really over the top, you-can’t-buy-a-toothbrush-that-hasn’t-been-tested-thirty-times-in-a-wind-tunnel sort of insane. Well, I’m exaggerating, but you get the idea.
The second reason is that the design is very, very simple. Now, of course the diameters and angles of the tubing, canister, impeller chamber and what-not have all been engineered very specifically in order to maximise filtration capacity. Ultimately, however, the filter consists of a bucket with two holes in, attached to a magnet spinning on a stick. That’s pretty much it. The motor is really just a copper coil encased in resin surrounding said magnet. There really isn’t that much that can go wrong with this design.
Finally, the canister is made out of good quality materials. The plastic is very tough indeed – I recently came across one that’s been running for longer than I’ve been alive, all the time on a balcony in tropical sun. Not bad. The filter clips are made out of malleable steel. In the event that you bend one out of shape, you can just bend it back with some pliers (or in my case, make your own). The silicon O-rings (three of them) last a very long time, but do need to be replaced eventually (about $20). The only part that really wears out is the impeller, which is similarly rather cheap to replace (if you know where to look). There is one glaring exception to all this, however, which comes in the form of the Q-tap connectors, which allow you to shut off the hose and disconnect the filter without going to the trouble of taking the pipes out of the aquarium. In my experience, they’re pretty rubbish. On the upside, you can really destroy them by snapping off the levers and they still won’t spring a leak.
Eheim Classics are extremely quiet. Unless they aren’t. More on that later.
The canisters are easy to clean and maintain (provided you have the Q-taps – it’s a love-hate thing). There are no media trays inside the canister, which does have the disadvantage that you have to spend an extra 2.5 seconds of your life to ensure the different filter media don’t mix together when emptying it for cleaning. But the real upside is that there is absolutely no flow-by with this filter. Cheaper filters (hint: pretty much any other filters) have a tendency to allow water to flow through the path of least resistance once the media clogs up, a process facilitated by the design of many filter baskets. There are exceptions to this rule, of course, but not that many. In practical terms, this means that the filter won’t stop filtering just because you haven’t cleaned it for many, many months (ahem), although the flow rate will decrease significantly. The lack of media baskets also means you can fit a surprisingly large amount of media into the filter.
On the subject of maintenance, a very common complaint about these filters is that they’re difficult to prime. Many people recommend that you fill the canister with water before attaching the tubing. Why? I’ll never know. The very first time you set up the filter, you need to suck on the outtake tube for about two seconds until you see the water pour over the U-pipe of the intake. Provided the filter is empty and everything else is in order, it will then promptly fill itself up without any further assistance from you. You then switch on the power. Not complicated. Should you happen to be more delicate in your manners, you can use one of the Eheim turkey-baster thingies to do the sucking for you, but the principle remains the same. Normally you’ll get air bubbles caught in the impeller making a bit of a racket, but it’s nothing a swift kick (or perhaps a gentle shake) can’t fix. It will usually work itself out in time anyway.
Another common complaint is that Eheims have a very low flow rate. There is some truth in this. Eheims rate their filters according to media capacity, not flow rate. To my mind, this is eminently sensible. Just because your tank looks like a hellish modern-day Charybdis doesn’t necessarily mean that you’re providing better filtration. In general terms, the size of the filter colony is more important than the rate at which water flows by them – provided there is sufficient current to prevent your filter from getting dead spots or going anaerobic (and did I mention that Classics don’t get flow-by problems?). It is true that some messier fish – goldies or cichlids – might benefit from the superior mechanical filtration that a very high turnover rate would provide, but normally it’s not necessary.
There is no mechanism to regulate flow rate with the Classics. In fact, there isn’t really a mechanism to regulate anything, except the wall socket (did I mention it’s a bucket with two holes in?). But in practical terms, the amount of filter floss and the cleanliness of the filter will regulate the flow quite considerably. For this reason, the filter will slow as it gets dirtier. This is not a bad thing. Don’t trust a filter that doesn’t slow down. The only way an increasingly dirty filter can maintain a stable flow rate is if the flow is bypassing the dirty media (which defeats the purpose of a filter in the first place). But enough about flow-by. Onwards.
Eheim provide a few different types of media. First, they provide carbon pads. Snore. You don’t use carbon unless you need to remove medications or tannins, or you live next to a toxic waste dump. They also provide a super-fine “polishing” pad. Silly idea, just slows down the flow a heap. What’s more interesting are the mechanical and biological filtration media. The mechanical filtration media are small, white ceramic tube-shaped pieces. In theory, these are part of the design that prevent the flow-through problem by breaking up the water current into a relatively uniform stream. Judging by the uniformity with which filter floss saturates with dirt, this might actually work. The biological medium is sintered glass balls. Now I’m not sure what that means, but apparently it provides maximum surface area for bacterial colonisation, while its regular shape ensures that it maintains a perfectly constant rate of flow between media particles. I’ve not the foggiest idea whether any of this is true, because although it intuitively makes sense, I’m not a bacterium and I don’t fancy trying to count them, either. You? But I do know that I’ve done some truly horrendous things to my 90 gallon tank (nicely aged escargot, anyone?) without getting the tiniest whiff of ammonia. Figuratively speaking, of course; if you can detect ammonia in your fish tank by smell alone, quit your job immediately, your vocation lies elsewhere (either that or your fish are already really, really dead).
There are problems with the Classic. The most obvious is the price. I mean, seriously, $250 bucks for a bucket / impeller on a stick? In theory, the extreme longevity of these filters (30 years plus) and the fact that it’s not likely to die on you in the middle of the night (risking an ammonia spike = dead fish) means that you’ll be financially ahead sooner or later. But I’m not entirely convinced by the economics. You can buy a perfectly functional SunSun for less than half the price, which not only works great, but looks like something you’d use to keep your lunch in, if you were an astronaut. Unlike the Classic, which as already mentioned, has a deeply unsexy appearance (unless you happen to have a thing for buckets; I won’t judge you). On the subject of appearances, the tubing is a truly awful green colour with “Eheim” plastered every five millimetres or so (presumably to avoid any confusion with that nasty, inferior, does-the-same-thing-for-one-fiftieth-of-the-price silicon tubing from eBay).
Second, the impeller shaft is brittle, and smashes easily. I can’t really blame Eheim for this – the fact that the impeller shaft is ceramic means it is very, very hard wearing and won’t deform even slightly, which is part of the reason Classics tend to be so quiet. Just be careful when you’re cleaning it.
Third, replacement parts are expensive. Not that expensive (try Rainbowkoi on eBay), but still dearer than any other brand. The flipside is that you’ll never have difficulty finding replacement parts, now or thirty years down the track. These filters have been in production for an extremely long time, and look likely to remain so.
Fourth, if you scratch the inside of the canister head – where the impeller fits – it will become noisy, and there’s nothing you can do to fix it. I have done this when using a wire hook to remove the rubber bushings that hold the impeller shaft in place (I’m assuming you won’t be this stupid). I’ve also done this by allowing course sand and other grit to be sucked up by the filter (much easier to do, but rarely a problem since the filter isn’t powerful enough to lift up a grain that’s large enough to cause damage – most of the time).
So what’s my summary of the time-honoured Eheim Classic range? They’ve caused me no end of trouble. I’ve blocked the filter intakes, blocked the outtakes, forgotten to clean the vents, scratched the impeller chambers, smashed the impeller shafts and generally spent many, many hours cross-legged in a small puddle trying to use spare parts I shouldn’t have bought to fix problems I shouldn’t have caused. But even after recently disposing of one, I couldn’t bring myself to use the proceeds to buy a SunSun (or two). I eventually purchased another Classic. It’s not just that I’ve developed a masochistic attachment to my tormentor. It’s that the more time I spend working on them, the more I appreciate the brilliant simplicity of the design, the remarkable quality of the materials and manufacture, and the idiot-proof operation (well, sadly, almost idiot-proof).
Just buy one. They're awesome. You might think you don't need one, because you already have filters for all of your fish tanks. You're wrong. This just means you need to buy more fish tanks, obviously.
Incidentally, I have used Jebo (horrible) Fluval (leaky) AquaOne (just %^$%$) and Penguin (nice) filters too.
I would include pictures, but you know what they look like by now (hint: a bucket).
So on to the review. The first and last thing that needs to be said about Classics is that they are very reliable. There are three reasons for this.
Eheims are famously made in Germany. I understand that the canister itself is now made in China for the Classic series, but since that’s really just a transparent green bucket I don’t view that as overly important. The reason why things made in Germany are good is not because of their proximity to all that delicious sausage and senf, it’s because German quality control and manufacturing standards are generally insane. I mean, in a really over the top, you-can’t-buy-a-toothbrush-that-hasn’t-been-tested-thirty-times-in-a-wind-tunnel sort of insane. Well, I’m exaggerating, but you get the idea.
The second reason is that the design is very, very simple. Now, of course the diameters and angles of the tubing, canister, impeller chamber and what-not have all been engineered very specifically in order to maximise filtration capacity. Ultimately, however, the filter consists of a bucket with two holes in, attached to a magnet spinning on a stick. That’s pretty much it. The motor is really just a copper coil encased in resin surrounding said magnet. There really isn’t that much that can go wrong with this design.
Finally, the canister is made out of good quality materials. The plastic is very tough indeed – I recently came across one that’s been running for longer than I’ve been alive, all the time on a balcony in tropical sun. Not bad. The filter clips are made out of malleable steel. In the event that you bend one out of shape, you can just bend it back with some pliers (or in my case, make your own). The silicon O-rings (three of them) last a very long time, but do need to be replaced eventually (about $20). The only part that really wears out is the impeller, which is similarly rather cheap to replace (if you know where to look). There is one glaring exception to all this, however, which comes in the form of the Q-tap connectors, which allow you to shut off the hose and disconnect the filter without going to the trouble of taking the pipes out of the aquarium. In my experience, they’re pretty rubbish. On the upside, you can really destroy them by snapping off the levers and they still won’t spring a leak.
Eheim Classics are extremely quiet. Unless they aren’t. More on that later.
The canisters are easy to clean and maintain (provided you have the Q-taps – it’s a love-hate thing). There are no media trays inside the canister, which does have the disadvantage that you have to spend an extra 2.5 seconds of your life to ensure the different filter media don’t mix together when emptying it for cleaning. But the real upside is that there is absolutely no flow-by with this filter. Cheaper filters (hint: pretty much any other filters) have a tendency to allow water to flow through the path of least resistance once the media clogs up, a process facilitated by the design of many filter baskets. There are exceptions to this rule, of course, but not that many. In practical terms, this means that the filter won’t stop filtering just because you haven’t cleaned it for many, many months (ahem), although the flow rate will decrease significantly. The lack of media baskets also means you can fit a surprisingly large amount of media into the filter.
On the subject of maintenance, a very common complaint about these filters is that they’re difficult to prime. Many people recommend that you fill the canister with water before attaching the tubing. Why? I’ll never know. The very first time you set up the filter, you need to suck on the outtake tube for about two seconds until you see the water pour over the U-pipe of the intake. Provided the filter is empty and everything else is in order, it will then promptly fill itself up without any further assistance from you. You then switch on the power. Not complicated. Should you happen to be more delicate in your manners, you can use one of the Eheim turkey-baster thingies to do the sucking for you, but the principle remains the same. Normally you’ll get air bubbles caught in the impeller making a bit of a racket, but it’s nothing a swift kick (or perhaps a gentle shake) can’t fix. It will usually work itself out in time anyway.
Another common complaint is that Eheims have a very low flow rate. There is some truth in this. Eheims rate their filters according to media capacity, not flow rate. To my mind, this is eminently sensible. Just because your tank looks like a hellish modern-day Charybdis doesn’t necessarily mean that you’re providing better filtration. In general terms, the size of the filter colony is more important than the rate at which water flows by them – provided there is sufficient current to prevent your filter from getting dead spots or going anaerobic (and did I mention that Classics don’t get flow-by problems?). It is true that some messier fish – goldies or cichlids – might benefit from the superior mechanical filtration that a very high turnover rate would provide, but normally it’s not necessary.
There is no mechanism to regulate flow rate with the Classics. In fact, there isn’t really a mechanism to regulate anything, except the wall socket (did I mention it’s a bucket with two holes in?). But in practical terms, the amount of filter floss and the cleanliness of the filter will regulate the flow quite considerably. For this reason, the filter will slow as it gets dirtier. This is not a bad thing. Don’t trust a filter that doesn’t slow down. The only way an increasingly dirty filter can maintain a stable flow rate is if the flow is bypassing the dirty media (which defeats the purpose of a filter in the first place). But enough about flow-by. Onwards.
Eheim provide a few different types of media. First, they provide carbon pads. Snore. You don’t use carbon unless you need to remove medications or tannins, or you live next to a toxic waste dump. They also provide a super-fine “polishing” pad. Silly idea, just slows down the flow a heap. What’s more interesting are the mechanical and biological filtration media. The mechanical filtration media are small, white ceramic tube-shaped pieces. In theory, these are part of the design that prevent the flow-through problem by breaking up the water current into a relatively uniform stream. Judging by the uniformity with which filter floss saturates with dirt, this might actually work. The biological medium is sintered glass balls. Now I’m not sure what that means, but apparently it provides maximum surface area for bacterial colonisation, while its regular shape ensures that it maintains a perfectly constant rate of flow between media particles. I’ve not the foggiest idea whether any of this is true, because although it intuitively makes sense, I’m not a bacterium and I don’t fancy trying to count them, either. You? But I do know that I’ve done some truly horrendous things to my 90 gallon tank (nicely aged escargot, anyone?) without getting the tiniest whiff of ammonia. Figuratively speaking, of course; if you can detect ammonia in your fish tank by smell alone, quit your job immediately, your vocation lies elsewhere (either that or your fish are already really, really dead).
There are problems with the Classic. The most obvious is the price. I mean, seriously, $250 bucks for a bucket / impeller on a stick? In theory, the extreme longevity of these filters (30 years plus) and the fact that it’s not likely to die on you in the middle of the night (risking an ammonia spike = dead fish) means that you’ll be financially ahead sooner or later. But I’m not entirely convinced by the economics. You can buy a perfectly functional SunSun for less than half the price, which not only works great, but looks like something you’d use to keep your lunch in, if you were an astronaut. Unlike the Classic, which as already mentioned, has a deeply unsexy appearance (unless you happen to have a thing for buckets; I won’t judge you). On the subject of appearances, the tubing is a truly awful green colour with “Eheim” plastered every five millimetres or so (presumably to avoid any confusion with that nasty, inferior, does-the-same-thing-for-one-fiftieth-of-the-price silicon tubing from eBay).
Second, the impeller shaft is brittle, and smashes easily. I can’t really blame Eheim for this – the fact that the impeller shaft is ceramic means it is very, very hard wearing and won’t deform even slightly, which is part of the reason Classics tend to be so quiet. Just be careful when you’re cleaning it.
Third, replacement parts are expensive. Not that expensive (try Rainbowkoi on eBay), but still dearer than any other brand. The flipside is that you’ll never have difficulty finding replacement parts, now or thirty years down the track. These filters have been in production for an extremely long time, and look likely to remain so.
Fourth, if you scratch the inside of the canister head – where the impeller fits – it will become noisy, and there’s nothing you can do to fix it. I have done this when using a wire hook to remove the rubber bushings that hold the impeller shaft in place (I’m assuming you won’t be this stupid). I’ve also done this by allowing course sand and other grit to be sucked up by the filter (much easier to do, but rarely a problem since the filter isn’t powerful enough to lift up a grain that’s large enough to cause damage – most of the time).
So what’s my summary of the time-honoured Eheim Classic range? They’ve caused me no end of trouble. I’ve blocked the filter intakes, blocked the outtakes, forgotten to clean the vents, scratched the impeller chambers, smashed the impeller shafts and generally spent many, many hours cross-legged in a small puddle trying to use spare parts I shouldn’t have bought to fix problems I shouldn’t have caused. But even after recently disposing of one, I couldn’t bring myself to use the proceeds to buy a SunSun (or two). I eventually purchased another Classic. It’s not just that I’ve developed a masochistic attachment to my tormentor. It’s that the more time I spend working on them, the more I appreciate the brilliant simplicity of the design, the remarkable quality of the materials and manufacture, and the idiot-proof operation (well, sadly, almost idiot-proof).
Just buy one. They're awesome. You might think you don't need one, because you already have filters for all of your fish tanks. You're wrong. This just means you need to buy more fish tanks, obviously.
Incidentally, I have used Jebo (horrible) Fluval (leaky) AquaOne (just %^$%$) and Penguin (nice) filters too.
I would include pictures, but you know what they look like by now (hint: a bucket).
