Monday, August 27, 2007


** Compliments to

It is a well known fact that Discus Fish require excellent water quality, and a good filter is at the heart of this. Now there is not one type of filter that suits a Discus Aquarium best as different filters do different jobs and it just depends on what you need it for.

Types of filtration

There are basically three types of filtration these are:

1) Mechanical
2) Biological
3) Chemical.


This is the first stage of any filtration; the water is drawn or pumped through layers of material that removes any free floating debris from the water. This is important, as sediment will block the next stage of filtration rendering it useless. If the flow rate of your filter drops off then clean or replace the mechanical media immediately.


The heart of the filter, basically bacteria will live in this area of the filter, they convert the fishes waste, (ammonia) to nitrite and finally nitrate, thus creating a safe environment for your Discus. Porous materials such as ceramics feature in the form of noodles and chips. These have millions of pores in which beneficial bacteria crucial to the removal of ammonia and nitrite, reside and establish colonies. It is important to never clean the media in tap water. You should rinse the media in tank water from water changes, when it is required.


The final stage of filtration is very much controlled by you, for various reasons you may wish to add carbon or peat to the filter, these filter media either absorb impurities, or alter the chemical balance of the water. This is usually topped off with a fine wool pad to polish the water as it returns to the aquarium.

Filtration Media

Filter media is the stuff that goes inside your filter mainly an external filter. It cleans the water and removes the harmful toxins from the water.

Mechanical Media

Any media will have mechanical capabilities, but the idea of dedicated mechanical media is that it protects the biological media from becoming clogged with debris. It usually tend to be sponges of some sort or the other. What ever you use it is best to use many layers to filter out the dirt. If maintained regularly then the mechanical media can washed out and re used several times, if left too long you will have to throw it away and replace with new media.

Biological Media

This is the heart of the filter and so long as you use sufficient pre filtration it is unnecessary to ever clean it. Biological filter bacteria live here, they colonize any nook, cranny or rough surface, so it goes without saying that the more surface area your media has the more bacteria will gather on it, thus improving the filtration process. Bacteria will cling to any surface from smooth gravel to the modern ceramic rings products which I use that offer massive surface areas. Ceramic rings products are available in any aquatic outlet and are highly recommended for any flow through filter. If at any stage the biological media does become clogged with muck, it is vitally important that it is washed in old tank water. Do not use tap water, you will kill all the friendly bacteria, which in turn leads to total filter failure, ammonia or nitrite poisoning and ultimately dead fish.

Chemical Media

It may at various times be necessary to add some activated carbon to your filter to remove medications or dyes from the water. Also you can use peat to soften the water, or perhaps Nitrate and Ammonia removing resins. Any chemical media should be last in line of the filtration process, and it is important to adhere to the instructions supplied as to the life span of these media, because some of them will let the toxins back into the water once exhausted.

Types of filters to use

Display tanks

If you have a Discus Fish display aquarium, then I recommend you use an external canister filter as these will keep the water very clean and it will have one of the largest surface areas for biological filtration which will make sure the water quality is excellent. It will sit outside the tank and you should be able to get one to fit any tank.

Alternatively you could use a trickle filter but they tend to be quite expensive. You could also use an internal filter but make sure it doesn’t cause too much current as Discus do not like strong currents.

Breeding tanks

In a breeding tank it is important to keep things simple. For this reason I like to have bare bottom tanks with just a sponge filter. Many breeders recommend this method as it has been tested and worked for years. A corner filter may also be used. This will give you a bit more control over the water as you can add some peat etc. I would not recommend using an internal power filter as the fry once free swimming will get sucked in and die. A sponge filter can be picked up cheap and is run by an air pump. Once every week, squeeze the sponge in the tank water you’ve removed from doing a water change as this won’t kill the bacteria in it.

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