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Water Quality Management for Freshwater Ornamental Fishes

Dr. Subhendu Datta Sr. Scientist, ICAR

Learning about water chemistry is often avoided by most aquarium owners, but by knowing just

the basics of water chemistry, you can greatly improve your success in rearing healthy fish. Most

aquarium owners are aware that the quality of water has a direct impact on the health of their

fish. But many aquarium owners do not understand the basic internal chemistry of their fish's

water, nor do they understand how to correctly or safely adjust it. Until the basics of water

chemistry are mastered and some common water maintenance techniques are learned, it will be

difficult to maintain a healthy and safe environment for the fish in your tank. The water quality is

by far the single most important factor in the health of your fish, and the more you know, the

better job you will do. This article provides a brief overview that is just the bare minimum that

aquarium owners should know and understand.

Fish obtain their basic necessities from the water in which they live. The most

characteristic feature of any aquarium system is therefore the quality of the water it contains.

This water must be obtained from some source, pre-treated to make it suitable for the fish,

delivered to the fish in sufficient quantities and maintained in good condition. Finally, it must be

disposed of. The water supplied to an aquarium is not pure, but contains dissolved and

particulate materials, some are necessary for the well-being of the fish and others are harmful.

Contamination may occur not only at source or form the animals, but often takes place within the

aquarium form the materials used in its construction. The volume of water supplied to an

aquarium may at first sight, seem to restrict the number of fish that can be maintained within it.

However, it is rarely the quantity of water per unit which limits the carrying capacity. The

capacity is usually set by the consumption of dissolved oxygen and the accumulation of toxic

metabolic products.

pH Every aquarium owner has heard of pH, but many do not understand the importance of

controlling it. pH is the measure of acidity or alkalinity in the water. The pH scale is from 1 to

14. A pH of 7 is neutral, which basically means the water is not acidic or alkaline. As the scale

goes down, for example 6, the water becomes more acidic. As the pH goes up, for example 8, the

water gets more alkaline. One very important part of the pH scale what most people do not

understand is that it is a logarithmic scale. What this means is that the pH changes at a tenfold

level between each number. For example, a pH of 5 is 10 times more acidic than a pH of 6, and a

pH of 4 is 100 times more acidic than a ph of 6. So if your fish are supposed to be at a pH of 7,

and the water level is 8, they are in water that is 10 times more alkaline than what they should be.

If the pH is 9, then they are in water that is 100 times more alkaline than what they need. So it is

easy to see why even a small change in required pH is stressful and potentially fatal to fish.

These examples really emphasize the importance in matching your fish closely to the

expected pH level of your water and then closely monitoring the pH. Putting a fish that requires a

pH of 8 with a fish that requires a pH of 6 is just not a good idea because one or both will be at a

very unacceptable level of pH and will be under a great deal of stress.

There are several different ways to influence your water's pH. There are chemical

additives that can be added directly to the water that will either raise or lower the pH. More

natural agents can be used to alter water pH as well. Peat in the tank or filter will acidify the

water. Mineral salts like calcium that are found in limestone or in some shells will cause an

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increase in alkalinity and pH. There is one important consideration in altering the pH of water

and that relates to the mineral content (hardness) of the water. See the section below for a

complete description. Remember that fish are very sensitive to changes in pH, and rapid changes

in pH can cause extreme stress and death. Fish should not be exposed to a change in pH greater

than 0.3 in a 24-hour period.

Tap water is usually alkaline. Always test tap water pH prior to making freshwater

aquarium water changes, and adjust as required. Marine aquaria should be maintained at a level

of 8.2 to 8.4.

Dissolved oxygen:

The majority of aquatic organisms need oxygen and must obtain it from the surrounding

water. The oxygenation or aeration of the water is therefore, of fundamental importance in any

aquarium, especially as the oxygen supply is one of the factors which may ultimately limit the

capacity of a particular volume of water for carrying fish.

The oxygen dissolved in water comes from two main sources: the atmosphere and green

plants. The actual content is a function of temperature, salinity and atmospheric pressure. Low

temperature, low salinity and higher atmospheric pressure favours more gas content (thereby

more oxygen) in the solution (water medium).

Aeration: Continuous aeration is very good husbandry since it mixes the water, supplies the

oxygen for the fish, removes carbon dioxide and maintains a constant temperature throughout the

tank. Many cheap air pumps are available in the hobby trade, though they are often noisy, are of

limited power and many frequently fail. If only one or two tanks are required, such vibratory

diaphragm pumps are acceptable, but a spare pump and several replacement diaphragms should

be stocked. The pump should be mounted above the tank level or the air-line fitted with non-

return valve to prevent back-siphoning when the pump is stopped or fails. A loop in the air-line 8

cm (3 inch) vertically above the tank’s water level will also prevent back-siphoning by absorbing

the oscillations when the airflows stops. The air tubes from the pump are connected to air stones

for providing minute air bubbles that diffuses the oxygen in water. Besides that it is also

connected to various types of toys and also for airlift pumping under for under gravel filtration.

For diffusion of more oxygen in water a micro pore air stone gets priority during selection of air

stones.

Nitrogenous waste products:

Perhaps the most pronounced and damaging changes to water quality originate with the

aquarium inhabitants themselves. In particular, water quality is impaired by the end products of

nitrogen metabolism. These include ammonia (either as the gas NH3 or ammonium ion, NH4),

urea, uric acid and other nitrogenous substances including proteins and amino acids. Ammonia,

especially, is one of the most harmful substances. Higher percent of un-ionized NH3 prevails at

higher pH and higher temperature. In ammonia poisoning, Gill becomes red, fish become darker

in colour and grasping at the surface layer. Acute toxicity levels = 0.4 ppm NH3. Chronic toxicity

levels = 0.05 ppm. This is common in new aquarium when immediately stoked to full capacity.

Ammonia can damage the gills at a level as small as 0.25 mg/lt. For immediate removal of

ammonia, use ammonia detoxifier such as Kordon's Amquel. Kordon Amquel removes ammonia,

chloramines, chlorine, and many other organic toxins. Completely non-toxic, contains no

formaldehyde, and will not affect dissolved oxygen levels. One teaspoon treats ten gallons.

However, it is best left alone until the bacterial load is sufficient. Note that the bacterial phases

will not take place unless the tank is initially stocked with feeder fish which can be removed

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after treatment. Test the water until the ammonia drops to nearly zero. At this time, we should

notice an increase in the nitrite level. When the nitrites are gone, it will be safe to add fish.

The conversion of the more toxic nitrogenous compounds to less toxic compounds is

achieved through organisms residing in water treatment units such as filters. In some aquaria,

algae are also used in nitrogen recycling. The process of combating the effects of nitrogenous

waste products is facilitated by low stock density, a high water turn over, aeration or oxygenation

of the water, frequent cleaning, removal of feces and waste food and by the provision of special

water treatment facilities.

Ammonia, nitrites, and nitrates

Ammonia, nitrites and nitrates are all part of the breakdown of waste in an aquarium. A

significant amount of fish and plant waste can accumulate in any aquarium. Uneaten food, algae,

and bacteria can also contribute to the waste load in an aquarium. As in all environments, this

waste needs to be broken down and either eliminated or turned into something that can be

utilized by another organism. In an aquarium there is a population of bacteria that is responsible

for this process. The breakdown of waste is a four-part process.

1. First, the waste from fish, plants, and food breaks down and releases ammonia.

2. This ammonia is very toxic to fish and must be converted by bacteria to nitrite.

3. The nitrite is also toxic to fish and must then be converted to nitrate.

4. The nitrate is not nearly as toxic and is taken up by plants or algae and used to help them

grow.

Ammonia is the most toxic product formed in water. Sources of ammonia in aquarium

water are fish respiration and digestion and decaying foods. Freshwater fish begin to be stressed

at levels of 0.50 ppm (parts per million). Marine aquaria levels should be less than 0.05 ppm.

Nitrate, nitrite, and ammonia are also removed through the weekly water changes.

Because high levels of ammonia and nitrite are lethal for fish, it is critical that these products be

efficiently removed or converted to nitrate.

Maintaining a population of bacteria that can convert ammonia and nitrite is an important

part of the water chemistry, and the process is known as biological filtration. Biological filtration

will occur naturally in most tanks that have been up and running for a couple of months. The

better filters often contain a special area or wheel that is made specifically for providing an

optimal habitat for growing these bacteria. While the bacteria will live in a traditional filter and

on rocks etc. in the aquarium, the new filters harbor a much higher number and can therefore do

a better job of removing ammonia and nitrites.

If a fish tank is overcrowded, or the waste level gets too high through overfeeding or

dead fish etc., even a properly functioning biological filter can be overwhelmed and toxic

conditions can result. Periodically checking the ammonia and nitrite levels in your tank with a

test kit will ensure that your biological filter is working correctly. Tanks that have a healthy plant

population will also aid in the removal of nitrates. Because it takes weeks to months for a tank to

grow a healthy population of bacteria, it is important that a tank be allowed to age before fish are

added. After the tank ages several weeks with only a few hardy fish, more fish can be slowly

added over a couple of months to make sure the biological filter is not overloaded.

High levels of nitrate can be present in the water of wells contaminated from fertilizer,

agricultural runoff, or sewage. These nitrates are dangerous to humans as well as livestock.

Nitrates can be removed by reverse osmosis or specialized nitrate removing chemicals.

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Fig. Biofilter cycling over time

Water Temperature: While not considered chemistry, water temperature needs to be mentioned. Fish are cold

blooded, which means they cannot raise or lower their body temperature and their body

temperature will be the same as the water around them. If a fish is kept outside of their normal

temperature range they will become stressed and become diseased or die. The majority of fish

are tropical, which means they come from tropical climates with water temperatures around

75ºF. Even cold water species such as goldfish cannot handle very cold water or sudden changes

in temperature. Know your species of fish and their temperature requirements.

Temperature is perhaps the most potent of all the environmental factors controlling and

governing the metabolism of animals. Water has a high thermal capacity compared to air; that is,

it can absorb a large amount of heat energy for a small rise in temperature. It, therefore, provides

a thermally stable environment.

In aquarium, fish are largely denied the use of any behavioural regulation, and the

aquarium design and management must compensate for this loss. Sudden change of temperature

in the aquarium should be avoided. Such as thermal shocks are most likely to occur when fish are

transferred from tank to tank or when they first arrive in the aquarium complex. A simple rule is

to float transfer containers plus fish in their new tanks until the temperature has equilibrated or

alternatively to slowly mix the water in the container with that in the tank over half an hour or

more. Increases in temperatures have the most distressing effect since respiration rate and

excitability increase while the oxygen-carrying capacity of the water decreases. Such

temperature increase in established tanks may result from refrigeration breakdown or thermostat

malfunction. The damage caused by faulty thermostat in a heated system can be minimized by

employing the minimum wattage heaters required for the temperature control or by including a

high temperature cutout in the circuit. This could simply be a second thermostat in series with

the first, but set to a slightly higher temperature so that it is on all the time during normal

operations. Such a thermostat should, however, be serviced regularly to ensure it does not stick

on.

During winter months necessary heating arrangements may be made for tropical

aquarium fish. A water heater of 5-6 watts capacity is required per gallon of water. Heating

equipment of the aquarium is basically an electric heating coil complete with thermostat to

control it both contained in glass tube. This submerged in the aquarium, connected to the

electricity supply and the built-in neon indicator. A thermometer is always kept inside the

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aquarium to monitor the temperature. It is placed at the front where it can be easily seen. It is

best arranged heater and thermostat at opposite corners of the tank to get correct temperature

readings of the aquarium water.

Water hardness Water hardness is often confusing and therefore overlooked by many aquarium owners.

Water hardness is important because it is closely related to pH and, just like pH, fish have certain

levels of water hardness that they thrive in, and if the hardness is too far off, it can cause stress

and death. Water hardness can be most simply described as the level of mineral in the water.

Hard water has a lot of dissolved mineral, and soft water has very little dissolved mineral in the

water. The most common mineral in water is calcium. However, other minerals can also be

present. Most people's tap water is either slightly hard or soft depending on where it comes from.

Well water from areas that have a lot of limestone (calcium) is often hard. Water that comes

from lakes (rainwater) is often devoid of mineral and is soft. It is important that you know the

hardness of the water that you use in your fish tank. Some species of fish require hard water and

others require soft water.

The other reason that hardness is important is that it affects pH. Hard water (high mineral

content) is usually high in pH. Soft water (low mineral) is usually low in pH. The mineral in hard

water will act as a buffer which will reduce the amount of acid in the water. The resulting water

will be more alkaline and higher in pH. The problem arises when we try to lower the pH in hard

water. If we add a commercial pH decreaser to an aquarium that is filled with hard water, the

mineral in the hard water will buffer the water and make it difficult to successfully lower the pH.

We would first have to remove the mineral from the water before we could effectively lower the

pH. The same is true for trying to raise the pH in acidic water that is soft and does not contain

much mineral. Until we add mineral to the water, it will be difficult to successfully alter and

maintain a high pH level. So what do we do? Well, it is not too hard to add mineral in the form

of calcium based rock, so making soft water hard and more alkaline (higher in pH) should not be

too difficult. To soften hard water, you need to take the mineral out with a water softener, reverse

osmosis or a specialized chemical that irreversibly binds up the mineral. Another option is to find

a source of demineralized water for your fish tank (rain water is soft in nature).

Of course the alternative to all of this may be to tailor your fish and plant species around

your existing water source. For beginning aquarist this may be the best solution. There are a wide

variety of tropical fish available and it is not difficult to find at least a dozen different species for

every different type of water. Any decent book on aquariums and tropical fish will list the

individual pH and hardness requirements of the different fish species. If the water is too hard for

your specific application (such as breeding certain species), simply mix it with deionized water

until the required hardness is obtained. Most hobbyists don’t feel the need to measure this

particular water quality.

Chlorine

Chlorine is commonly added to water supplies to disinfect the water (to kill bacteria) and

can be harmful to fish. It is lethal to fish at 0.2 - 0.3 ppm. It can be removed with chemical

chlorine eliminators or by aerating the water in a bucket over night.

Phosphates Phosphate is a salt, commonly found in tap water, which serves as an algae nutrient.

Maximum phosphate levels are 2 - 3 ppm with less than 0.05 ppm being ideal. Reef tanks should

be maintained at less than 0.05 ppm.

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Importance of Water quality management in aquarium

Nothing is more important in aquarium keeping than water quality management. There

are many excellent products available out there to assist in water quality management, but there

is still no replacement for water changes, good filtration, and good feeding habits.

Water Changes:

Changing water in more frequent, smaller amounts is preferable to larger less frequent

changes. Make sure the water going in has the right chemistry (pH, etc.) and temperature.

Weekly water changes are probably the most important part of maintaining good water quality.

Weekly water changes of around 15%-20% of the total water volume will correct many potential

problems in water quality. The water changes will bring fresh mineral rich water into the tank.

The fish, plants and bacteria use up the trace minerals in the water and by adding new water

weekly you replace these minerals. By removing water you reduce the amount of nitrate and

ammonia that builds up in the water as well. Weekly water changes also help remove other

toxins or pollutants that can build up in the tank. If a siphon with a gravel cleaner is used the

gravel can be cleaned and uneaten food and fish and plant waste can also be removed. This keeps

the ammonia levels down and the water cleaner. (If you have an under gravel filter or a filter

system that does not have a biological filter you may not want to disrupt the good bacteria by

over cleaning the gravel).

Remember that most tropical fish live in environments where currents or rainfall

regularly bring fresh water and remove waste. By providing weekly water changes we help to

simulate this natural and much needed requirement. An important note about water changes is to

make sure the total does not exceed a third of the water volume. It is also important that the

water that is added is free of chlorine. Otherwise use a declorinator (sodium thiosulfate), if

chlorine or chloramines are present. (Wonder shells remove chlorine, stabilize KH, and add

electrolytes). Water changes are important for Nitrate removal and buildup of toxic organic and

inorganic material.

Routine partial changes of the water are necessary to dilute the build-up of soluble

materials (due to accumulation of fecal and unfed materials). Evaporation losses should be

replaced by suitable water (artificially prepared or natural). The cleaning can be done by hand;

the hands should be washed with shop, after the job and not before because of the danger of

introducing soap into the water. Use scraper for algae on glasses. The toys, air stones and other

equipments, which have the algae and other sediment attachment, should also be cleaned. Plants

should be trimmed and decaying leaves should be removed regularly at the time of water

exchange.

Sound and Vibration:

It is often forgotten that many fishes are acutely sensitive to sound and other mechanical

disturbances of the water. Though the hearing of most species is restricted to low frequencies

(below 3 kHz for nearly all fish, and below 1 kHz for most), at these low frequency and

amplitude many species produce sounds especially during courtship.

The aquarium is often a very noisy place, with underwater noise levels in aquarium tanks

often very much higher than those in the sea or in freshwater. Much of the noise comes from the

machinery; pumps and compressors associated with the aquarium, and characteristically contain

strong single frequencies in its spectrum. Human footfalls, doors opening and closing etc. can

also be troublesome, and their strongly impulsive nature may evoke startling response from the

aquarium inhabitants. Vibration is transmitted to the water mainly through the floor and tank

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supports but also through the water pipes. Therefore, machinery; pumps and compressors, which

are producing unnatural sound, must be replaced at the earliest.

Some important aspects of water quality:

Aquarium should be filled with clear portable water. The quality requirement of water in

the aquarium depends on the types of the fishes being kept there. The tap water is probably the

safest source of aquarium water for majority of tropical fish and plants (see below the

requirement for breeding). But it contains chlorine, which is toxic to fish even at low

concentration. To remove the chlorine naturally, it is better to allow maturing the water for few

days or aerating overnight before its addition. During emergency conditions dechlorination can

be done with the commercially available chemical (sodium thiosulphate) purchased from the pet

shop.

The degrees of hardness have several biological effects upon aquatic life. Bicarbonates

tend to prevent a solution from changing in acidity. Soft water, lacking this protection, may

become particularly acidic when much carbon dioxide is present; such a change creates stress for

organisms. For soft water species excessive hardness causes an organism problem in absorbing

substances through its delicate membranes. This is most true of the sensitive naked cells of eggs

and milt, so that soft water has been found to play a vital role in the successful reproduction of

many species of freshwater fishes. Thus, at least for the purposes such as fish breeding, a soft

solution is desirable.

To maintain soft water, all sources of calcium carbonate such as calcareous rocks,

gravels, coral, broken shell and algae must be kept out of the aquarium system whilst using only

soft water initially and during exchange. Conversely, presence of such sources will preserve the

water hardness. Some of the important water quality parameters and their optimum ranges for

maintaining the fish in aquarium are presented in the table below:

Temperature

pH

CO2

Alkalinity

Hardness

Dissolved oxygen

Free ammonia

Ionised ammonia

17-380C

7.0-8.5

< 5 ppm

75-250 ppm as Ca CO3

50-200 ppm as Ca CO3

5.0-10.0 ppm

<0.05 ppm

<0.1-0.4 ppm

Parameters Ideal for breeding

SL.

No.

Name of the fish Water Temperature

(oC)

pH Water hardness

(mg/L CaCO3)

Egg layers

1. Gold fish (winter

breeder)

18 - 20 7-7.5 90-200

2. Koi carp (winter

breeder)

20 - 22 7- 7.5 70 - 200

3. Angel (summer

breeder)

22 – 32 (breeding)

28 – 30 (larval

6.3 – 8.5 70 - 200

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CAUTION

Adjustment and/or corrections to existing water chemistry MUST be made gradually.

Stability is as important as water quality.

Softening Your Water (i.e., lowering the hardness):

Some fish (e.g., discus, cardinal tetras, etc.) prefer soft water. Although they can survive

in harder water, they are unlikely to breed in it. Thus, you may feel compelled to soften your

water despite the hassle involved in doing so. Water hardness is of interest to aquarists for two

reasons: to provide the proper environment for the fish and to help stabilize the pH in the

aquarium. There are two types of water hardness: general hardness (GH) and carbonate hardness

(KH). A third term commonly used is total hardness which is a combination of GH and KH.

General hardness is the more important of the two in biological processes. When a fish or plant is

said to prefer "hard" or "soft" water, this is referring to GH. Incorrect GH will affect the transfer

of nutrients and waste products through cell membranes and can affect egg fertility, proper

functioning of internal organs such as kidneys and growth. Within reason, most fish and plants

can successfully adapt to local GH conditions, although breeding may be impaired.

Typical home water softeners or demineralisers soften water using a technique known

as "ion exchange''. That is, they remove calcium and magnesium ions by replacing them with

sodium ions. Although this does technically make water softer, most fish won't notice the

difference. That is, fish that prefer soft water don't like sodium either, and for them such water

softeners don't help at all. Thus, home water softeners are not an appropriate way to soften water

for aquarium use.

Fish stores also market "water softening pillows". They use the same ion-exchange

principle. One "recharge" the pillow by soaking it in a salt water solution, then places it in the

tank where the sodium ions are released into the water and replaced by calcium and magnesium

ions. After a few hours or days, the pillows (along with the calcium and magnesium) are

removed, and the pillow recharged. The pillows sold in stores are too small to work well in

practice, and shouldn't be used for the same reason cited above.

Peat moss softens water and reduces its hardness. The most effective way to soften water

via peat is to aerate water for 1-2 weeks in a bucket containing peat moss. For example, get a

(plastic) bucket of the appropriate size. Then, get a large quantity of peat (a gallon or more), boil

it (so that it sinks), stuff it in a pillow case, and place it in the water bucket. Use an air pump to

aerate it. In 1-2 weeks, the water will be softer and more acidic. Use this aged water when

making partial water changes on your tank.

Peat can be bought at pet shops, but it is expensive. It is much more cost-effective to buy

it in bulk at a local gardening shop. Read labels carefully! You don't want to use peat containing

fertilizers or other additives. Although some folks place peat in the filters of their tanks, the

technique has a number of drawbacks. First, peat clogs easily, so adding peat isn't always

rearing)

4. Gourami (summer

breeder)

24 - 30 6.0 – 7.0 60 - 100

Live bearers

5. Sowrd tail (-do-) 28-30 6.5 – 7.5 80 - 250

6. Platy (-do-) 28-30 6.5 – 7.5 80 - 250

7. Guppy (-do-) 28-30 6.5 – 7.5 80 - 250

8. Molly (-do-) 28-30 6.5 – 7.5 80 - 250

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effective. Second, peat can be messy and may cloud the water in your tank. Third, the exact

quantity of peat needed to effectively soften your water is difficult to estimate. Using the wrong

amount, results in the wrong water chemistry. Finally, when doing water changes, your tank's

chemistry changes when new water is added (it has the wrong properties). Over the next few

days, the chemistry changes as the peat takes effect. Using aged water helps ensure that the

chemistry of your tank doesn't fluctuate while doing water changes.

Hard water can also be softened by diluting it with rain water, distilled water or R/O

water. Rain water is a good and cheap source of soft water. Harvest the rain water in fibre or

cemented tanks. However, if there is any factory or industry nearby to your home or aquarim

units and it is continuously emiting smoke in the sky and polluting the environment, then be

careful. In such cases, rain may be very acidic and corrosive. R/O (reverse-osmosis) water is

purified water made by an R/O unit. Home drinking water filtration units having R/O system

(around Rs. 10000/-) can also be purchased at stores. Unfortunately, R/O units are slow and

running a large unit with R/O system may be expensive for most hobbyists. The same applies to

distilled water system as well.

AQUARIUM FILTRATION SYSTEMS

There are three basic types of aquarium filtration system.

Biological Filtration

Biological filtration is the term used to describe beneficial bacteria, which is established

during the initial cycling of the aquarium. These bacteria break down ammonia and nitrite and

convert them into the less toxic compound nitrate. It is widely acknowledged throughout the

aquatic community that these bacteria require a surface to attach and oxygen rich water.

Biological filtration is essential and needs to be adequately established in every

aquarium.

It is recommended to medicate fish in a separate tank (hospital tank) when using

antibiotics (anti bacteria), as extensive use of these medications will kill the bacteria.

Live rock and sand are by all means biological filtration as well. In theory you could maintain an

aquarium with these alone, however the tanks fish population would be restricted to small

numbers. Always keep in mind, that biological filtration requires oxygen. An inadequate or

interrupted supply will result in the failing of your biological filtration system

Saltwater tanks can be successfully maintained using only a protein skimmer and

biological filtration.

Chemical Filtration

Chemical filtration removes dissolved wastes. The most common type of chemical

filtration is activated carbon. Others, such as Algone absorb ammonia, silicate, phosphates and

so on. Carbon has established itself as “a must have” in the aquarium. Still, be aware that some

carbons leach phosphates. Another media for chemical filtration consists of zeolite, which will

delay or disrupt biological filtration, especially during the cycle.

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Mechanical Filtration Mechanical aquarium filtration removes solid particles from the water via the aquarium

filter. It does not remove or convert ammonia, nitrite or nitrate. This filter type actually provides

a means to remove free-floating waste before it decays. Mechanical filtration will only be

beneficial if the filter material is replaced every 2-4 weeks because the waste will still decay

while trapped in the filter material. To save money on replacements, you can also rinse the filters

in use or use an alternative filter such as filter floss, which costs only a fraction of replacement

cartridges.

Common types of filter media are paper cartridges, sponges, and floss. Mechanical

filtration will be ineffective on matter that settled in the gravel. Use a siphon to remove these

particles. Kill two birds with one stone – siphon during water changes! Be aware, that beneficial

bacteria will settle on the filter media. Take this under consideration, and replace part of the

media at a time if it’s possible. Sponges will clog quickly and paper even faster. Filter floss is

very efficient due to small and large openings, which will not clog as easily. Another benefit of

floss is that you can easily do a partial change, reducing the amount of bacterial settlements that

are removed.

AQUARIUM FILTERS

Corner Filter

Water is forced through it. On the inside you would find filter floss or other

media. It is mainly a physical/mechanical filter. Beneficial bacteria settle on the

medium and provided biological filtration. This very inexpensive filter is an

excellent way to set up a hospital tank. Buy one for pennies on the dollar and

use some gravel from your established tank. You will immediately have a

working biological and mechanical filter for your hospital tank.

Canister Filter

Basically an enhanced corner filter. A closed box where water is forced

through filtration media (mechanical and/or chemical). It can be placed inside the

aquarium, or outside (underneath the aquarium or as hang on type). The canister

filter has the most powerful mechanical filtration system, and can be used with

messy eaters. The down side is that it requires frequent cleaning. Bacteria will

also settle in this filter type. Biological filtration can be improved, by placing wet

dry wheels at the outflow of the canister filter.

Fluidized Bed Filter

This filter is a recent development, using sand as a bacteria settlement media. In

a tubular design, sand is fully submerged in water. The water is pumped upwards

through the sand, allowing bacteria to settle within. Additional tubes can be used as pre-

filters (mechanical) and also for chemical filters using activated carbon. This filter

provides a large surface for bacteria colonies, but sometimes lacks in providing enough

oxygen for their performance.

Power Filter

The very easy to maintain power filter hangs on the back of the aquarium (easy access).

Water is pulled through a mechanical filtration, using floss and insert cartridges. They

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also provide enough space for chemical filtration media. Within the last few years a wet dry

wheel (biowheel) was developed, to provide an even larger area for bacteria to settle. Wash it

once in a week. Cost: Rs. 400-1000/-

Protein Skimmer

The protein skimmer is a chemical filtration method. It takes out dissolved

biological waste before it can decompose. This is achieved by a tubular design with

air bubbles inside. The waste is attracted to the surface of air bubbles, which then

rises to the water surface. There, a skimmer removes the biological waste. This

filtration type has revolutionized reef tanks. It only works with high pH and salinity.

This filter is for salt-water use only.

Sponge Filter

A sponge filter looks like a tube with a sponge like material inside. As water flows

through, bacteria will colonize the porous foam and establish a biological filtration.

These sponges also serve as a mechanical filter, removing larger particles from the

water. The advanced versions use two sponges, making it easier to preserve bacteria

colonies by replacing the sponges at different times. Using a sponge from an

established aquarium can also jump-start a new tank or quarantine/hospital tank.

Undergravel Filter:

The undergravel filter (UGF) is basically a perforated plate below the

gravel. Water is pumped upward through the gravel by air bubbles, water stream,

or a combination of both. This slow flow of water and oxygen allows the bacteria

to colonize the gravel. The UGF is an aid for biological filtration. It does not

remove larger waste particles. It has to be well maintained, especially through

vacuuming of the gravel. UGF’s are inexpensive, but have a tendency to clog up. It is

recommended to replace this filter as they age. Of course, they can be combined with a power

head as a pre-filter for larger particles.

Wet–Dry Filter:

Also known as trickle filter. This kind of filter was designed with consideration of the

oxygen demand of beneficial bacteria. It consists of a plastic tube with unsubmerged

media (floss, bioballs etc.) over which water trickles – hence “Trickle Filter”. The wet

dry filter provides a large air to water surface. The larger the surface structure of the

media gets the better it works. This filter provides no mechanical filtration and works

on the principle of the wet dry wheels.

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