Aquarium sponge filters - An alternative
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Sponge filters are ideal for breeding tanks, the fry will not get sucked up the inlet pipes and with some of the more modern sponges that are now available, they can even be used in the large display tanks. Quarantine tanks benefit from these as well; if the filter is allowed to run in another set up it can simply be transferred to the “Q” tank as and when required. Because these are so simple to set up, they are ideal for beginners and experienced fish keepers alike. Unfortunately sponge filters will not remove any medication added to the hospital tank so bear this in mind after finishing a course of treatments.
So how do they work?
Basically water is pulled through the sponge, trapping debris; the colonized bacteria in the sponge remove the ammonia and nitrites. To create the suction required an air lift tube, pierced with small holes is placed centrally in the sponge, inside this an air line is run and as the air bubbles rise the water is sucked through. In some of the larger filter sponges a power head may be attached instead to give greater filtration power. The top of the uplift tube is normally level with the water surface so that the returning water will pull oxygen back into the tank. The height of the return tube is purely optional as in some tanks it is set to only reach to halfway up the water level, this will then just provide a low current through the tank.
A new sponge filter will not clean the water straight away, as with other filters the sponges require seeding first (building up a colony of beneficial bacteria).There are several ways to do this. If placed in a new tank set up the filter can be seeded in the traditional way of letting the tank run through its cycle, but the beauty of these filters is that they are several quicker methods that can be used.
In my case I normally remove the sponges and float them in my display tanks for a week, by that time they will have picked up enough bacteria to keep another tank filtered efficiently from day one. Other keepers, that I have spoken to, take the sponges and literally drag them through the gravel of another tank, picking up debris etc. This is instant seeding although I have never tried this method so I cannot comment as to whether it as quick as they say.
One of the main drawbacks with filter sponges is that the sponges will clog up, because of this they need to be cleaned on a regular basis, normally once a week. It is easy to spot when it is time for the sponge to be cleaned as the flow rate will slow down quite rapidly. Even though this is the main disadvantage it is quite an easy task to get the sponge nice and clean, ready for use again. The sponge should simply slide off the tubing, then with gentle squeezing, rinse the sponge in old tank water or even de-chlorinated water. If maintained properly the life span of the filter is anything up to 10 years.
Remember- Never use tap water to clean the sponges it will wipe out your bacterial colony, then the filter will need seeding again before it can filter the tank.
Interpet sell a range of the filters, the size of the sponges can vary, some of the filters have twinned tubing so that 2 sponges can be run at the same time.
A single sponge filter costs as little as 3 pounds (6 dollars), whereas the double sponge filter retails at 5 pounds (10 dollars).These units run a ribbed sponge which increases the surface area of the sponge, replacement sponges can be purchased for as little as 2 pounds (4 dollars).These also have the advantage of a multi directional uplift making positioning of the current in the tank very easy.
Many discus keepers favor sponge filters for their set ups, this is due to the high biological efficiency that they run at. Hung Huey provide larger sponge filters for this purpose, I have kept a 60 gallon discus tank running one of these successfully in the past, as mentioned above, the only maintenance required was a regular de-clog of the sponge. A standard 600 liter filter only retails at 12 pounds (24 dollars), the larger models increase in price up to 20 pounds (40 dollars). A power head can be attached to this range of filters for increased water flow.
Another option is to make your own, quite easy to do and it will be just as efficient as a factory made model. All that is required is:-
- A large cube of filter sponge (available at most pet stores)
- Rigid tubing
- An airline with air stone
- Cut the sponge diagonally to give you 2 triangular pieces.
- Make a hole in the sponge so that the rigid tubing can slide inside, it will need to be at least halfway down the sponge.
- An easy method of doing this is to load the sponge with water, then freeze it. The hole can then be drilled to make a nice clean fit for the tubing.
- Clamping the tubing securely, make a series of holes at the end that will be inserted into the sponge. This can be done with a hammer and a sharp nail.
- Insert the tubing into the sponge, and then either place your air line inside a small power head onto it.
- If a power head has been fitted there will be enough weight to keep the filter submerged, if using an airline attach the filter to the tank by means of suckers.
Online suppliers of sponge filters
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