“ Brand: Eheim / Animals Equipment Type: Aquarium Equipment „
My 300 litre aquarium is stocked to quite a high density with Lake Malawi cichlids. Such a high stocking density requires scrupulous filtration to ensure that the inhabitants stay in the best of health.
I decided to buy two external filters for my aquarium to supplement the in-built one. I decided on Eheim filters as they're reputed to be the most reliable on the market. One of the filters was the Eheim 2227-51 Wet/Dry Filter.
Aquarium filters perform two main functions; mechanical and biological filtration.
Mechanical filtration is simply the removal of suspended particles from the aquarium water (usually bits of fish poo!), keeping the water sparklingly clear.
Biological filtration is far more important. Fish excrement breaks down to form ammonia, which is lethal to fish at levels of around one part per million. In natural waters, the large volume of water dilutes this pollutant and bacteria gradually convert the toxic ammonia to nitrite (still toxic but not as toxic as ammonia) then nitrate which is fairly non-toxic to fish. The nitrate produced is removed by regular water changes.
Aquarium filters provide a substrate (usually sponges or pieces of porous rock) for these beneficial bacteria and a pump passes water through the filter allowing a much greater concentration of bacteria in one place than is usually possible.
The one problem with this approach is that the conversion from ammonia to nitrate uses oxygen, which the bacteria remove from the water, reducing the amount of oxygen left for the fishes.
The Eheim 2227 Wet/Dry filter takes a slightly different approach to biological filtration. The filter contains a valve which alternately fills and empties the canister, exposing the filtration media (and it colony of bacteria) to oxygen from the air, then aquarium water.
In this way, the filter, rather than removing oxygen, actually adds it to the water, ensuring that the fish have a sufficient oxygen supply.
The Eheim 2227 is a futuristic looking item. The translucent green plastic, blocky design and the 'float' chamber on the front of the unit give it quite a sci-fi look. When it's operating the 'float' moves up and down inside the filter, almost looking as if the filter is breathing. The filter has a flow rate of 1050 litres per hour, so 'turns over' the contents of my tank three times every hour.
There are three pipes leading from the filter. The first is the long inlet pipe which must be placed near the bottom of the aquarium to draw water into the filter. The second is the return pipe which is usually placed at the surface of the aquarium. The third pipe is a 'breather' which is involved in the wet/dry operation. This hangs over the back of the aquarium.
The top of the unit houses the pump and is removed to access the body of the filter. Inside the filter are two media trays. This is where the filter media is held. Importantly, the Eheim 2227 is not supplied with media; this must be purchased separately. Eheim Substrat Pro is recommended to fill the trays. This is a porous rock-like material with a huge surface area to hold a massive amount of beneficial bacteria.
In use, the Eheim 2227 is a superb piece of kit. The wet/dry action ensures that the filter can support the maximum amount of bacteria; I've never detected any ammonia or nitrite since this filter has been settled in (or 'cycled'). I suspect that the unit could filter an even larger aquarium than mine.
Despite the filter's superb operation as a biological filter, it provides almost no mechanical filtration. It cannot, therefore be used as the only filter in an aquarium. The filter is supplied with a small sponge to fit over the end of the inlet pipe. This is supposed to be taken off after a couple of weeks. I have left mine in place to ensure that no solid waste finds its way into the filter. Doing this means I have to rinse the sponge every week or so to remove solids trapped in it.
Mechanically, the unit has been in operation for several years and nothing at all has gone wrong with it. It continues to work efficiently, with a quiet rushing sound as the wet/dry mechanism does its work.
Cleaning the filter is another matter, however. The unit is designed to effect easy cleaning. The power is shut off, the inlet and outlet pipes are isolated with toggle valves, and the four strong clips holding the lid in place are released.
This gives access to the media trays which must be rinsed in used aquarium water every few months to remove any particulate contamination. Tip: don't use tap water as the chlorine can kill the bacteria.
Having cleaned the filter, I often find that, when put back together, the wet/dry mechanism will not start. It's often a matter of trial and error to get the thing to work properly. Once the wet/dry mechanism is operating, it works faultlessly, but the delay in getting filtration working again is frustrating.
The minor problem of cleaning aside, this is an excellent filter. Eheim make possibly the best filters in the world and this is one of them. The quality is reflected in the price, unfortunately. This filter costs around £150 which is far more expensive than other, cheaper, external filters.
I chose to pay this, however, because it's an Eheim, and because of the wet/dry device which keeps my aquarium well aerated and free from biological pollution. Anyone wanting a top quality external filter could do worse than look at this model. The price may put many off, however.
For Tank Litre/Gal: 350/77 / Pump Output: 1050 L/H / Filter Circulation: 550 L/H