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#1 anchar

anchar
  • Forum Member
  • Joined: 28-January 04
  • Location: Bullcreek

Posted 13 September 2006 - 11:55 PM

Filtration
by David Midgely

I currently have 14 tanks in my fish garage all setup with varying species of Lamprologines. I keep Julidochromis sp., Chalinochromis sp. and the odd Neolamprologous sp.. Some readers will know I am also involved with ACE (Australian Cichlid Enthusiasts an online association of cichlid keepers (current numbering well over 1000 members). We get a large number of queries about which types of filters are best for african cichlid aquariums. I run virtually all my tanks on simple air driven filters, and while I know the hobby is obsessed with water turnover, powerheads and other "hardware" I thought it was worth a brief look at another method of filtration once more popular now out of style.

Sponge Filters

At the cheap end of the spectrum, sponge filters provide excellent and efficient form of biological and mechanical filtration. There are a number of types available and generally at low (< $10) cost. Most are relatively simple uplift connected to one or two sponges and are powered by air displacement of water in the uplift tube via an airpump (for which I recommend Schego brand).

One of the currently available types features an upright uplift tube with the sponge inline and a heavy weight at the base to allow it to stand on the tank floor. My preferred style of sponge filter is those filters where a single uplift runs one or two sponges (the latter is preferable) either perpendicular to the uplift tube, or parallel (connected via a "U" piece). Such systems are normally attached to the wall of the tank via suction cups. The two-sponge models are, in my opinion, particularly useful as one sponge (alternating sponges every month) can be cleaned harshly (under running water) without causing problems with the biological filtration.

Sponge filters also have an advantage over corner style filtration as, if used in tanks with small fish or fry, the occupants can feed directly off the filter. This is particularly useful when finely powdered foods are being served.

Mechanically, the sponge fitler is probably inferior to the corner filter, that has a greater capacity to trap coarse particulate waste. Like corner filters, sponge filters can be used in any sized aquarium, however, multiple sponge filters (or sponge filters driven by powerheads) may be required in larger aquaria.

The sponge used to make sponge filters is difficult to source in Australia - and commonly bought sponge for DIY versions tends to be of a fine grain and less useful. Assuming the correct type of sponge (coarse grained) can be obtained sponge filters can be easily manufactured from a simple PVC uplift (use electrical conduit), attached to an "L" elbow joint to which a further piece of PVC (with holes drilled in, and one end blocked) is attached. In order to drill the right sized hole in the sponge to insert the PVC emerse the sponge in a container with enough water to completely cover it. Freeze it and use a hole cutter to cut through the sponge and ice simultaneously. Caution is advised when using the drill around water (albeit frozen).

Corner Filters

In most of my tanks (most are 80 litre, 2' tanks) I have a single corner filter. I dont have undergravel filters in any of the tanks nor do I use additional filtration in these tanks such as canister or HOB filters. I don't have any unexplained fish deaths, in my sporadic checks for ammonia and nitrite and am yet to find any.

I have been setting up my corner filters in much the same way for some time. I half fill them with a coarse filter material. This is usually gravel, very coarse shell grit or the ceramic noodles often available for filling canister filters. Below this, ie: closer to the bottom of the filter, I put a layer (3-5cm) of filter wool. The order of these materials is probably unimportant, though if you set the filter up the other way around you need to change your filter wool more frequently. In a world that sells "bioballs" this filter doesn't seem to have enough biological filtration. But it works and as such, must have. Moreover, all my tanks are high pH (8.0ish), any ammonia in these tanks is far more toxic than at lower pH's so I've a lot of confidence in the system.

So if they are so good why doesn't everyone use them? I think this is a matter of aesthetics these arent the most beautiful of filters they sit in the corner (or in my case, the middle of my tank, I'm proud of my erronously named "corner" filters) and do their work. Additionally, in larger aquariums, single corner filters arent sufficient, to get them to work you need more than one. While I do like the humble corner filter I don't like the idea of having six in a larger aquarium, I'm keeping fish, not filters, after all. In such tanks, sumps (or above tank trickle filters) or a variety of other filters are superior.

If you have a small tank or a few small tanks and you want an efficient, inexpensive (mine cost me ~$3.95 ea!!) filter then these are the filters for you!



The correct use of activated carbon (charcoal) in aquariums and their filters
by Andrea Watts

What is Activated Carbon?

In its original form, charcoal is very light due mainly to its porosity. It contains phosphorous, sulphur and heavy metals - all of which are highly undesirable in an aquarium. It is sourced from the combustion of wood, lignite, bituminous coal, peat, or coconut shells. The activation process involves either thermal (carbonization and gasification) or chemical (with zinc chloride or phosphoric acid) reactions. These processes eliminate all impurities (elements other than carbon), and increases the overall porosity.

Activated carbon is marketed for aquarium use and is available in powder and granules. It can either be purchased in convenient sachets (which are simply placed into the filter), or as loose matter used to fill a specialized compartment. It is very important that the carbon is thoroughly rinsed to remove the dust or residue that is produced during its manufacture.

Why use Activated Carbon?

Adsorption is the basic principle of filtration i.e. the removal of impurities. This occurs when the undesirable molecules are trapped in the pores and outer surface of the carbon. The filter's performance is linked to the available surface area, and therefore to the porous nature of the material contained in the filter.

There are conflicting theories arising from the use of activated charcoal in an aquarium. Firstly, some people believe that it should be used permanently. The second school of thought promotes the occasional use of carbon. Personally, I believe that generally it is unnecessary to use filtration over activated carbon continuously. It is best used in response to particular requirements, such as the elimination of toxins, medicinal residue, or pigments such as tannin (given off by wood or peat).

Filtration over activated carbon can prove useful in the long term to treat water containing high concentrations of undesirable substances like chlorine, chloramines, alum, phenols and insecticides and pesticides. Reverse osmosis systems are usefully coupled with activated carbon pre-filters. Used in conjunction, they eliminate chlorinated by-products than can damage the membrane. However, they are not very effective in the removal of nitrogenous by-products. Only the rigorous upkeep of biological filters and efficient biological filtration can help eliminate ammonia, nitrite and nitrate.

The Negative Impact of Activated Carbon Activated carbon can be criticized for its inability to differentiate between "good" and "bad" molecules. It also fails to retain important trace minerals, including those needed by many hard water fish species and many plants. In reality, the adsorption power of activated carbon is dependent upon the different parameters (e.g. pH of the water) or the chemical form under which the element in question is found. The power of adsorption is limited and it losses its fixation capacity after several days, once it has become saturated. Even worse, it may then release the molecules it had previously extracted back into the water. Therefore, it must be replaced frequently; frequency being dependent on the saturation or concentration level of undesirable elements in the aquarium.




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