Article Filtration 101 (In General)

Filtration

Purpose Of Filtration:
Filtration plays a key part in enabling aquatic keepers to have healthy clean aquariums.

Aquatic species emit biological waste (feces) which must be effectively removed & metabolized before it becomes toxic to the tank inhabitant/inhabitants.

Filtration facilitates the removal of such wastes.

-> Proper Aquatic filtration should consist of Mechanical, Chemical and Biological Filtration...in addition to providing oxygenation.

What is Mechanical Filtration?
The removal of solid particles from within the water enabling cleaner water, higher oxygenation and a reduction in accumulating nitrates.

How does it work? Normally, a fine material such as floss or sponge is used to screen the larger debris/waste and prevent it from reentering the aquarium. This is commonly found in all filtration systems and usually comes in the form of a sponge, cartidge or other loose media that will need to be placed within the filters media tray slot, cartridge or basket.

-> This type of media will "clog" rather quickly and needs to be rinsed/replaced quite frequently.

What is Chemical Filtration?

Utilizing chemicals as a filtering substance in order to change the chemical composition of water. Chemical filtration most commonly refers to the use of activated carbon or other "cleaning" resins.

When the water is so clean it's invisible, you're seeing the benefits of utilizing excellent chemical filtration.

Activated carbon pulls dissolved organics from the water by adsorbing them and is made from various base materials that have been heated then steam-treated. This steaming process makes the carbons surface area extremely porous enabling adhesion.

How does it work? As the water passes over the carbon, the carbon chemically attracts the pollutants (Waste, odors, color) to adhere to its surface trapping them and preventing them from re-entering your aquarium. However, the carbon exhausts rather quickly (usually 2-4 weeks on average) and needs to be replaced on a regular basis.

How can I tell if my carbon is exhausted? Water will usually have a yellowish tinge to it and in some cases the water may carry an odor to it.

What is the best kind of carbon to purchase? A high quality carbon with a disclaimer stating that it won't cause a PH Spike and one that is spherical in shape. Spherical is superior since it does not "pack" together and enables a higher surface area allowing the maximum amount of adsorption.

Are their other chemical filtration medias available? Yes, their are many on today's market that normally "target" one or several "problem" areas that most aquarists tend to face. Many are specialty resins and proprietary blends of other compounds.

A few chemical filtration medias:
[*]BioChemZorb by Aquarium Pharmaceuticals will normally last 6 months and not only cleans the water, but will also polish the water giving your tank impeccable clarity.

[*]Ammonia Chips are designed to remove ammonia from water.

What is Biological Filtration?
Utilizing various strains of beneficial/Nitrifying bacteria that reside within a established filter system in order to convert the end result of waste sources (feces, decaying fish, decaying plants, shedded leaves, etc) from toxic ammonia and nitrite into the less harmful by-product referred to as nitrate.

How is this achieved? In a properly cycled aquarium with proper filtration the constant incoming of water from the filter provides enhanced levels of oxygen, providing a excellent environment for beneficial/Nitrifying bacteria to rapidly grow.

-> Note that these "beneficial/nitrifying" bacterias performance can be affected by various things that are normally related to your tanks stability (temperature, water quality, ph, etc).

How can I help the beneficial/nitrifying bacteria? By performing regular tank maintenance on a regular basis. (ex. routine weekly water changes, always adding a dechlorinator such as Prime each and every time you add water, regular water testing, avoiding temperature fluxations, monthly cleaning of your filtration system, removing debris daily, avoiding overfeeding, etc).

What Types Of Filters Are Readily Available?
[*]Canister: An external tall box-like system.

Tubes extend from the canister and reach inside the aquarium...suck the water out of the tank and run it through the canister which has all three levels of filtration: a filter medium on which bacteria can grow, a layer of chemical filtration such as activated charcoal, and a physical barrier.

-> Canisters are usually more expensive than the other types of fish tank filters, but more efficient and very easy to maintain.
[*]Hang On Back/Power: Boxes that hang on the back or side of the fish tank.

A long tube goes into the aquarium and sucks water up into the filter...the water then flows through a series of chemical and physical barriers and then cascades back into the tank. Some provide filter media on which bacterial colonies can grow as well.

-> This type of aquarium filter is very efficient and easy to clean. The filtration material is usually on small trays that can simply be pulled out and either washed or discarded when they become dirty.
[*]Corner: Sits inside the tank, normally in the corner and is used in small fish tanks only.

It consists of a small plastic box with holes or slits in the sides, bottom, and lid. Inside there are two layers. Activated charcoal goes in the bottom and provides chemical filtration and cotton, polyester batting or filter material sits on top of the charcoal to provide mechanical filtration. A small external pump sucks the water through the bottom and out through the top.

This type of aquarium filter is inexpensive, acceptably efficient for smaller fish tanks, but is difficult to maintain. Whenever the filter medium needs to be changed, the entire canister must be taken out of the tank, cleaned, and then replaced. This is extremely disruptive to the aquarium.

[*]Under Gravel: consists of slotted plastic trays that sit on the bottom of your fish tank under the gravel.

Long, plastic tubes are attached to the under gravel filter and power heads are often used at the top. Power heads are pumps that suck the water up from under the under gravel filter and spray it out over the surface of the water.

-> Under gravel filters are the most ineffective. Debris such as fallen fish food can be sucked down through the gravel and remain in the water under the plastic trays. These aquarium filters should be used only with another type of filter.

[*]Fluidized Bed:This uses a fluidized bed of sand.

This filter is roughly similar in principle to the reverse flow undergravel filter, but with much higher water flow. The higher water flow keeps the sand clean of debris, while at the same time allowing the development of large and efficient colonies of beneficial bacteria.

-> Problems include oxygen depletion and clogging.

[*]Sponge:Sits inside the tank.

Water is forced through a porous foam, either by a powerhead, or air bubbling through an airlift tube. Water flowing though the sponge allows the growth of a colony of beneficial bacteria which neutralizes toxic ammonia.

One style of sponge filter uses two sponges attached to one lift tube. These have the advantage that the sponges can be cleaned one at a time, reducing bacterial loss. Also, one of the sponges can be removed and transferred to a new tank, bringing with it a colony of beneficial bacteria, and thereby "jump starting" the cycling of a new tank.

-> Sponge filters provide an efficient and cheap form of biological filtration.

[*]Wet/Dry or Trickle:usually sit below the aquarium and have a hose/hoses reaching into the aquarium.

These work on the principle that the beneficial colonies of ammonia and neutralizing bacteria grow best in the presence of well oxygenated water.

By "trickling'' water over unsubmerged plastic gizmos or other media, wet/dry filters provide a very large air/water surface area. They come in many shapes and sizes.

Many things can used for the media, with the best providing great amounts of surface area, while at the same time having large openings to reduce the tendency to clog and ensure efficient gas exchange.

-> The problem of clogging of the media can also be reduced by prefiltering the water with an efficient mechanical filter, and (when used) with a protein skimmer.
[*]Protein/Foam Fractionators: sit on the floor below your aquarium or hang on the back.

Protein skimmers have the unique ability to remove dissolved organic wastes BEFORE they begin to decompose.

This is accomplished by taking advantage of the fact that organic chemicals are attracted to the surfaces of bubbles which are passed in large numbers through a column of water. The foam is then "skimmed'' off the water, while at the same time removing the organic wastes.

-> The foaming process only works in a water with high pH and salinity, and as a result skimmers are primarily for saltwater use.

[*]Ultraviolet/UV:Typically sit outside the tank and either hang on the back of the tank or are mountable.

High intensity ultraviolet light destroys the DNA in living cells and can be an effective means to control living pathogens.

The most effective UV light is the high energy UV(C) light roughly at the wavelength of 250 Angstroms.

To be effective, UV Sterilization (UVS) must expose the pathogens to high enough light intensity for a long enough period of time at roughly 10 to 25 gallons per hour per watt .

Common problems which can reduce efficiency and kill rate are:

1) Allowing the water to flow too fast past the UV light.
2) Light blockage due to a build up of salt deposits or bacterial slime on the bulb.
3) Fading of the light due to age of the bulb (which typically have a six month life.)

There are three types of UV Sterilizers:

#1) Tray type. (Typically homemade) with UV bulbs suspended in a reflecting fixture over a shallow tray of slow flowing water. Benefits: easily cleaned, can be cheap, can be made large enough for commercial applications.

-> Problems: safety risks to your eyes, too large and awkward for many home uses.

#2) Tube type, Wet bulb. Tube types have the benefit of exposing all sides of the UV tube to water with no reflector. The water passes directly past the bulb which is mounted in a waterproof tube. Benefits: cheap, compact and effective.

-> Problems: difficult to clean the slime accumulations from the bulb, safety risks due to electrical shock.

#3) Tube type, Dry bulb. Similar to above, but the UV tube is surrounded by a quartz tube [glass blocks UV(C) light] insulating it from the water. Some of these types come with sensors to monitor the intensity of the light to let you know when to replace/clean the bulb. etc..


-> These are more expensive and probably safer. Changing the light bulb is easier and dry bulb tube types can have a internal device to wipe slime from the quartz tube.

Special care MUST BE TAKEN to avoid direct or indirect eye contact with this type of light :!:

Filtration Purchasing Tips

[*]Make sure it has a high Gallon per Hour/turnover rate with the awareness that once filled with media that this rating will definitely decrease. Minimum suggested turnover rate is 5x your aquarium volume. This is one area where "overkill" is recommended in regards to the flow rate. Keep in mind want excellent filtration...not fish blown out of the water! I suggest looking around first, getting some opinions then check for additional reviews to help narrow down your choices.

[*]Make sure it has enough media options/placing to suit your needs. If you are trying to conserve electricity check the power consumption that the filter uses. Also note that may aquarists utilize non-traditional media such as broken pieces of terra cotta, 100% polyester batting, lava rocks, etc. in order to keep media costs minimal.

[*]Make sure you have enough clearance/room for it (whether you put it in your tank, behind your tank, under your tank or besides your tank) and that it will be easily accessible for regular maintenance.

Information regarding Seeding A filter can be found here:

http://www.theexoticfish.com/viewtopic.php?f=18&t=2628

 

Thanks Guido.
Hopefully it will be helpful for the people just getting into the hobby!

 

Thanks Greg!