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actinic lights
Actinics are a type of fluorescent light that is very blue. This is the color of light that is most useful to the chlorophyll in marine life, and is the color of the sea below 10 meters.
activated carbon
This is carbon, looking like crumbled charcoal. It can absorb many compounds out of the water, and is especially good at removing yellowing compounds to keep the water clear. Carbon must be changed regularly, as after it has been used for a while, it may leach impurities back into the water.
Refers to freshwater cichlids from Africa. These fish come from the very hard, slightly salty water of the rift lakes.
air pump
A pump which supplies air for lift tubes, skimmers, bubblers, etc. The most common type are diaphragm pumps, though cylinder pumps are available for large installations.
Plant-like organisms which grow in water. While many algae grow as a fuzz or slime without much visible structure, some is leafy. Other algae is hard and calcareous.
This is the measure of a solution's resistance to changes in pH. It is commonly measured as carbonate alkalinity or total alkalinity, and is expressed in meq, dKH, or ppm of C03 ions. The alkalinity can be raised by adding a buffer.
NH3, this is one of the steps in the nitrogen cycle. It is toxic to most creatures, and should be at un-measurable levels after a tank has cycled.
Literally without air, refers to an area where there is no dissolved oxygen in the water. While necessary for some things such as bacterial reduction of nitrate to nitrogen, these areas can also produce hydrogen sulfide and other undesirable substances.
The substance that makes up coral skeletons and coral sand. It's a form of CaCO3.
See brine shrimp.
The electrical supply for some lights, such as fluorescents and metal halide bulbs. These are available in several varieties, such as tar, transformer, and electronic. They must be properly matched to the type of bulb you are using.
biological filtration
These filters make use of bacteria to break down wastes in the water into substances which are less toxic to the inhabitants, in a process known as the nitrogen cycle. Examples are under gravel filters, sponge filters, and trickle filters.
Water that part-way between freshwater and marine. A number of species prefer partly-salty water.
brine shrimp
Sometimes sold as sea monkeys, these shrimp grow to about 1/4 inch and are used as a live food for fish. They are easily hatched and their eggs may be stored dry for years.
bubble filters
These internal filters use a lift tube to draw water through a foam block, as in a sponge filter.
A substance which is dissolved in the water to boost the alkalinity and/or adjust the pH. Buffers may be formulated to adjust the pH to a particular value, or to raise the alkalinity without changing the pH.
calcium chloride
CaCl2. This is a form of calcium that may be added to reef tanks to maintain the calcium level. However, kalkwasser (calcium hydroxide) is preferred, as adding kalkwasser does not upset the alkalinity or ionic balance the way calcium chloride can.
calcium hydroxide
Ca(OH)2. See kalkwasser.
canister filter
This filter consists of a canister external to the aquarium which is filled with various media, mechanical or chemical. Hoses run to and from the canister, and an attached pump forces water through the canister. These can be very efficient filters, though they must be taken apart and cleaned regularly.
See activated carbon
carbon dioxide
The gas CO2 is a necessary nutrient for plants, and can be used to lower the pH.
chemical filtration
These filters use chemical processes to clean the water. Examples are protein skimmers and any filter containing chemical media such as activated carbon, molecular adsorption pads, or resins.
A device which makes aquarium water cooler. They generally cost at least several hundred dollars, and home brew solutions involving small refrigerators are seldom successful.
This substance is sometimes used as a bactericide in municipal water supplies. It it poisonous to fish, but can be removed with special dechlorinating compounds. Unlike chlorine, it will not evaporate from water by itself.
This substance is commonly used to keep bacteria out of municipal water supplies. It is poisonous to fish, but can be removed with special dechlorinating compounds, or by letting a bucket of water sit open for 24 hours.
A family of freshwater fish found naturally in South America and Africa. Most of them are very aggressive fish.
A device which measures some parameter of an aquarium, and then switches on and off another device to affect the aquarium. Typical controllers include redox, and pH.
cylinder pump
A type of air pump which can produce great volumes of air, though they are noisier than the more common diaphragm pumps.
A process for filtering tap water before it is added to the aquarium. It comes with either separate or mixed-bed resins. The mixed-bed resins are disposable when they are exhausted, whereas separate resins can be recharged, though that requires working with caustic chemicals.
diaphragm pump
The most common type of air pump. A great variety of brands and styles are available which produce different amounts of air, with differing amounts of noise.
diatom filter
This purely mechanical filter uses diatomaceous earth to remove very fine particles from the water. They clog quickly and are only used occasionally as water polishers rather than continuously.
Single-celled creatures with hard, silica-based shells. They look like a golden powder coating the tank to the naked eye.
These cichlids come from South America. They are somewhat delicate, large round flat fish, often with blue or red marbled coloring.
DLS (double-layered spiral) is a material made by rolling up a polyester pad and plastic wire mesh. It is used in both biological and mechanical filters.
dosing pump
A pump which can supply a very slow drip which is used to add trace elements or make up water for evaporation. The most common type is a peristaltic pump.
external filter
Any filter not kept inside the aquarium, but connected with hoses. Canister filters are an example of these.
Filters are devices which clean the water. They come in three broad categories: mechanical, chemical, and biological. There are many different types of filters, such as...
foam fractionation
See protein skimming.
Halogen lights have a very yellow light not appropriate for aquarium use. Do not confuse these with metal halide lights.
A device to warm the aquarium water. They are available as submersible heaters, over-the-side heaters, and under tank coils.
internal filters
Any filter operated inside the fish tank. under gravel filters and sponge filters are two examples of these.
These are animals without backbones. In freshwater aquaria only snails and crayfish/shrimp are generally available. For marine aquaria, many kinds of animals are available.
A trace element necessary to life in very small quantities, but deadly at higher concentrations. Because it is removed by protein skimming, it must be added regularly on skimmed tanks. It is especially needed by crustaceans to successfully molt and soft corals for growth.
Literally chalk-water, this is water with calcium hydroxide Ca(OH)2 dissolved in it. Adding kalkwasser is the preferred way to maintain calcium levels in a marine tank with growing corals, clams, and calcareous algae. About 1 teaspoon of Ca(OH)2 powder will dissolve in a gallon of pure water.
This family of small freshwater fish are seldom found in pet stores. They live only one year, laying eggs that can survive harsh conditions.
lift tube
A source of water movement used with under gravel filters and some other filters, such as sponge filters. Large bubbles are released in a tube about 1 inch wide. As they rush upwards, they pull the water in the tube up as well.
live bearers
Fish which produce live young rather than laying eggs. These freshwater fish include guppies, mollies, platies, and swordtails.
live rock
These are rocks removed from the vicinity of a tropical coral reef with all of the life intact on them. They commonly have algae, sponges, worms, feather dusters, small crustaceans, polyps and urchins on them. Live rocks are an important way to build up a complete and stable ecosystem for a coral reef.
mechanical filtration
These filters mechanically remove particles from the water. Examples are under gravel filters, canister filters, and wet/dry prefilters.
metal halide
Metal halide lights are a type of light bulb which burns very white and very bright. They require a special fixture and ballast. They are the closest thing we have to artificial sunlight, and are typically used on reefs and planted tanks. They are very efficient in terms of lumens/watt. Do not confuse these with halogen bulbs, which have a very yellow light not appropriate for aquarium use.
molecular adsorption pads
These are polyester pads which have been chemically treated to absorb certain substances from the water. This form of chemical filtration is placed in a canister or power filter. Note that they sometimes will remove good trace elements as well as pollutants.
The process by which ammonia is changed to nitrite, then nitrate, and finally nitrogen gas. See nitrogen cycle.
NO3, this is a product in the nitrogen cycle. It is not toxic, though at high levels can cause some distress. In a reef tank it should be kept as low as possible, under 10ppm. Fish only tanks can generally stand 30-40ppm.
NO2, this is one of the steps in the nitrogen cycle. It is toxic to most creatures, and should be at un-measurable levels after a tank has cycled.
nitrogen cycle
The nitrogen cycle describes how organic wastes break down in the aquarium. Fish wastes naturally decompose into ammonia, which is highly toxic. Nitrosomonas bacteria process the ammonia into nitrite, which is also toxic. Nitrobacter bacteria then break down the nitrite into nitrate, which is much less harmful. This is as far as the cycle goes in most tanks, though under the right conditions, the nitrate is further broken down to free nitrogen gas.
A gas, O3, which is very reactive. It is used as a sterilizing agent to kill bacteria and small organisms in the water. It is used in an ozone reactor or protein skimmer. It is important not to use too much ozone, and to filter ozonated water through carbon before returning it to the tank, as excess ozone can harm fish and other creatures.
This form of dried moss can be used as a filter material to soften water and make it more acidic.
peristaltic pump
A dosing pump which works by using rollers to squeeze flexible tubing.
A measure of the "power of Hydrogen", or how acidic or alkaline a solution is. Some fish are particular and want some specific pH, others will live at any of a range of values. Most are sensitive to changes, which should only be made gradually.
power filter
A filter which hangs on the side of a tank or is submerged in it, containing an internal pump to draw water through. They provide mechanical filtration, and optionally chemical or biological filtration.
A small submersible pump. They have only one moving part, called the impeller. They are useful to create current within a tank or to drive filters such as under gravel filters, canisters and protein skimmers.
This is a small mechanical filter attached to the input to another filter, usually biological. It is there to make sure that the biofilter does not get clogged with gunk, decreasing its effectiveness.
Redox, or reduction-oxidation potential, is a measure of how easy it is for organic reactions to take place. This is an indicator of water quality, measured in millivolts with a special probe. Higher values are better. Redox controllers use an ozone reactor to raise the redox potential.
reverse osmosis
A process for filtering tap water before it is used in an aquarium. This process generates water slowly and wastes a couple of gallons of water for each gallon of filtered water produced. However it is one of the easiest home methods.
reverse under gravel filter
This variant of an under gravel filter runs in the opposite direction, pushing water up through the gravel. It requires water pumps of some sort to run, but needs cleaning less often.
See reverse osmosis.
protein skimmer
This chemical filter, also called a foam fractionator, sends many small bubbles through a column of water to separate dissolved organic compounds from the water. They come in three varieties, venturi, counter-current, and co-current. They are only effective in salt water. They may be placed in the tank, hung on the side, or placed in a sump.
A device used to add a substance to the aquarium water in a controlled manner. Ozone, kalkwasser, and carbon dioxide are the most common reactors. They are typically a chamber water is pumped through with an injector for the additive.
sponge filter
This filter provides both mechanical and biological filtration. It consists of a large foam rubber (sponge) block connected to a lift tube or small power head. Water is drawn through the sponge, which removes small particles and grows bacteria.
This trace element is necessary for corals, clams, and other creatures with calcareous skeletons to grow. It is most commonly added as strontium chloride SrCl2.
An additional water reservoir, typically under a tank, to keep equipment out of sight or increase the amount of water in a system.
trace elements
These are chemicals that are needed in small amounts by the aquarium creatures to survive, like vitamins. They must be replenished with food, water changes, or specific additives.
trickle filter
This form of a wet/dry filter provides primarily filtration. Water is dripped over some media which is also exposed to the air. This promotes very efficient nitrification. The water may drip from a spray bar or drip plate. The medium may be small pieces of plastic, DLS, or anything else which will support bacteria and not easily clog.
See under gravel filter.
ultraviolet sterilizer
A device which uses UV light to kill bacteria and other tiny organisms.
under gravel filter
This filter provides both mechanical and biological filtration. It consists of a perforated plate placed on the bottom of the aquarium and then covered in gravel. Water is pulled through the gravel, under the plate, and up through lift tubes.
A type of valve which produces bubbles by drawing air into quickly flowing water. It is sometimes used on protein skimmers.
wave maker
A device which switches powerheads on and off at timed or random intervals, to simulate wave action in an aquarium.
wet/dry filter
This is a form of biological filtration which has media exposed to the air to aid in nitrification. Common forms are trickle filters and rotating "paddle wheel" filters.
A naturally occurring ore which will absorb ammonia and soften water. It is only effective in fresh water.
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