All about Aquarium Filters

[lorba]

by nicky :


Filters

There are many different types of commercially available filters. They can be broadly classified into the following categories.

1. Canister Filter - External
2. Overhead Filter (OHF) - External
3. Undergravel Filter (UGF) - Internal
4. Corner Filter - Internal

The primary purpose of filter in an aquarium is to reduce the toxic level of fish/animal waste. (what else???)

(Some aquarists may counter that with a planted-setup, filter does not serve this primary purpose because waste of fish/animal are essentially food for plants. While this theory is valid in a low tech, low bio-load setup, one must recognized that for most people, the ideal bio-load in a planted setup is often exceeded because of the ever presence urge to add more attractive/interactive fishes into the setup.)

When properly positioned, filter can creates the much needed water movement in a planted setup. Some aquarists also use the outlet of filter to drive the CO2-reactor.


Types of Filters and their function in a Planted Setup

CANISTER FILTER:
This external filter works by sucking water out of the tank and push the water back into the tank using an impeller, after allowing the water to move through the filter media. As the water passing through the filter does not come into contact with air and does not subject to violent turbulent and cause CO2 to escape in the process (unless the outlet is placed above the water-surface), this filter is considered by many as ‘ideal’ for planted-setup. It can be easily fitted to work with device such as surface skimmer, CO2-Reactor or chiller.

OVERHEAD FILTER:
This method of filtering water is generally not ideal for planted setup and should be avoided when possible because CO2 lost is inevitable even with care taken to ensure splashing is kept to the minimum. Another disadvantage of this filter in a planted setup is the blocking of lights due to the general placement/position of the filter. If this filter must be used, take special care to ensure that the water outlet is below the water surface and the inlet of water into the filter medium is cushioned.

UNDERGRAVEL FILTER:
The main draw back of this filter in a planted setup is the highly probably leak of base-fertilizer. Even in a setup where base-fert are not used, this filter is still not ideal as the air-bubbles that are required to drive the convection current past the substrate will cause water surface to ‘break’ thereby allowing CO2 to escape. Advocates of UGF highlight the need to circulate water through the substrate to avoid anaerobic regions. Under-gravel heater can be used to serve the same purpose.

CORNER FILTER:
This is generally suitable only in a small setup (under 2x1x1ft setup). Some aquarists also connect the CO2 source to the inlet of the filter thus bypassing the need for a CO2-dissolving device. The main drawback of this filter is the general low capacity of bio-waste and the tendency for the filter to be chocked. Some aquarist do not favors the filter because of its presence in the water.


Filter Media:
???

[loupgarou]

Diatom Filters

Diatom filters are specialiused filters that uses diatomaceous earth as its filter media, along with a micron filter bag or a micron pleated filter.
The prominent brands are Vortex, Magnum, Whisper, System 1 , but these are not widely distributed in Singapore and have to be ordered online from the USA. I've seen the Magnum 350 at Soon Heng 88 and Happy Aquarium.

Diatom Filters are used to "polish" water. Most models cannot be run continuously (ie: the filter clogs up eventually and must be cleaned) but some models of the vortex filter can.


Denitrators
There are two kinds of denitrators. these are specialised filters designed to remove excess nitrates from the water. However, they are usually more trouble than they are worth and DO NOT eliminate the need for water changes.

Aenaerobic Bacteria filters are based on certain bacteria species that consume Oxygen from nitrates (NO3), this results in the formation of pure nitrogen in the absence of oxygen. However, these filters usually require a long setup time (ie: 4weeks) or so, and can be easily disrupted. They must also be fed on a glucose solution.

Sulphur denitrators are based on bacteria that consume sulphur and oxygen from nitrates. However, these filters must be run meticulously according to manufacturer instructions, Too fast a flow rate through the filter results in the production of NO2 (nitrites) and too slow a flow rate results in the production of H2S (Hydrogen sulphide) . Both of which are highly toxic.


Ultraviolet filters
These are specialised filters that radiate UV light within a quartz compartment in which you circulate tank water through. they are effective against free floating pathogens and algae (green water). Anecdoctal reports also say they can have a negative effect on plant fertilisers but most users do not report any such problems. the UV filter must be turned off when medicating the tank. The UV bulb also has an effective lifespan and must be replaced periodically.

[benny]

Sponge? FBF?

Cheers,

[gks]

"Natural" biological filters using plants, particularly water hyacinth and duckweeds, are marvellously low maintenance.