Eheim Filters
By Walter Spanner

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Eheim Filter - Parts

Eheim filters have been around for a very long time now and have a very good reputation for quality and reliability. Perhaps that sounds like a sales ploy, but it is true. Years ago I had what they now call Eheim Classic filters and they are still selling them.
So now on to the nitty bitty bit, the problem solving part, of cleaning them and priming them. Hopefully some of this info can be useful for any other fish keeper’s using these excellent filters.

First of all, those seals around the top, and where the pipes connect, keep them well coated in ‘Vaseline’.
Next, when you are cleaning out the impellor make sure that all the grot is removed from the bottom and inside of the body that the impellor sits in. This is essential so as to keep the impellor cool and smooth running.
When cleaning the head of the filter take great care to clean right down the little hole that is in the surrounding area. It is only small, and a lot of people miss this one out. It is there to allow water down to the bottom of the impeller body to cool it and keep it running free, but this hole clogs up in time.
Next is the priming of the filter, which a lot of people have trouble with. Assuming that the filter is empty and clean, make sure that the outlet pipe is completely free from any water as this will stop the priming of the filter. (Even if there is water in that bit of pipe that goes into the tank, you know the bit that has the U bend in). Now leave off the outlet pipe which comes off the filter box and with all taps on (if taps are fitted) give the outlet a good suck, (a spare piece of pipe helps with this). Then when you hear that the water is flowing into the filter box, you can put the outlet pipe back on. Depending on the size of the filter you should have plenty of time to get that pipe back on, so don’t panic about it.
Another thing that could cause a problem, is the gunk that builds up in the pipe. When you see that your green pipes are black inside, pull them off when doing the next filter clean and pull a long pipe cleaner through them. Doing this will keep the flow rate up.
Keeping that Blue filter sponge clean also helps, as when this gets clogged it draws air in and makes the filter hiss.
When you have started up your filter there will be, for a while a hissing noise from the pump. To clear this, give it a rock to and fro as this will allow the air to be released from the filter.
Hope this will help, as all these things that I have written, all work for me and others that I have told about them.


Q. What type of media do I use for a long-term biological/mechanical filtration?

A. From the bottom of the filter box. Ehfimech, then Ehfifix Pad, then Ehfisubstrat and finally Ehfisynth Pad.

Q. Why is it that my filter is not working as well as it did when I first bought it?

A. Most probably likely to be a build up of algae/gunk in and around the impellor. This must be kept clean at all times, as it will in time wear out the bearing shaft. As the bushing gets old, it loses its grip on the shaft and allows the shaft to spin with the impellor. When this happens they both spin simultaneously and cause a reduction in flow.

Q. What is the difference between Biological, Mechanical and Filtration?

A. Biological - A build up of toxic nitrogenous wastes is a natural result of all aquarium inhabitants. In nature the large body of water is enough to dilute these wastes to be used up by other organisms and then be converted to a less toxic chemical. In the aquarium however these poisonous toxins cannot be converted without the use of a powerful biological filtration. Without this conversion from toxic to less harmful waste the fish will slowly poison themselves.
If you use Ehfimech, which is made of hollow ceramic material and holds back the solid dirt particles (at the same time) it provides an intensive stream of turbulence in the water and an even flow of water through all layers in the filter.
Then put the blue coarse filter pad in.
Use Ehfisubstrat in the top basket. This consists of highly porous sintered glass, which is used as the main filter medium and has a huge surface area and allows lots of bacteria to colonise.
Then use the white fine filter pad on top.

Mechanical - This is where the filter works by trapping the particles of waste as they pass through.
Again we use Ehfimech in the bottom layer to trap the solids and to allow an even flow of water through out the filter.
Then in the next layer we use Ehfifix, which is a medium mechanical filter. This is placed between the Ehfimech on the bottom and any subsequent biological or chemical filter layers. This traps debris, which has passed through the bottom layer and acts as a divider.
On the top we use Ehfisynth, this is a completely natural wool, and will trap any fine particles of dirt. It can come loose or in a pad.

Filtration - Absorptive filtration is a process in which dissolved substances are captured by solid bodies such as carbon. These dissolved substances can be harmful to fish. They are generally of chemical origin such as chlorine in tap water. (Alkaline residues of aquarium medication and even some dissolved).
With all types of carbon the effectiveness is short lived and to stop the absorption being washed back into the tank they must be changed. Also remember that if you are using any medication the carbon must be removed before any treatment can start, as the carbon will absorb the medication.
Recommend Ehfikarbon, which is a high quality carbon is for short term use, and is to be used in freshwater tanks only. You still have to use sponges to trap the waste.
The combination of materials is endless as you could make up your own if you like, as long as it does the job of keeping the toxins down and keeping the water clear, then that must be OK with us.

Here is a list of Eheim filters recommended to run, XXXX size tanks

Recommended filter for XXXX size tank

12 - US Gallons
8 – 16
16 – 42
26 – 53
From 53
16 – 26

So, as these machines are so reliable please don’t just run them into the ground. Just remember to keep your Eheim filter clean on the inside, keep the pipes clean and your Eheim will give you many years of reliable filtration.
AS I have said at the beginning that the priming of these filters can be tricky and is one of knack.
First make sure that the filter box is empty of water and also the outlet pipe is completely empty including the U bend that goes just in the tank.
Next make sure that the filter tap is turned on at the outlet pipe and remove the outlet pipe. Put a piece of pipe over the outlet hole and with the inlet tap turned on give it a good suck. When you here the water running into the filter box put the outlet pipe back on and clamp it up.
Then when the filter box is full then you can start the pump giving it a shake now and again to dispel any air that is in the filter box.
Keep those pipes clean, as this will reduce the flow of water.

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