To keep your aquarium clean and your fish healthy, a filter is essential. It will remove waste products such as fish excrement, food remnants, or decomposing plant parts from the water and recondition it. There are various types of filters. I recommend inside or outside filters driven by a rotary, or centrifugal, pump.

Inside filter: Attach the filter in one of the rear corners. It has a limited effect and therefore should be used in small tanks. In large tanks it is usful as ancillary equipment--for example, to produce a stronger water current.

Outside filter: Place the outside filter next to the aquarium or on aquarium stand. It can be used for both small and large tanks. This filter often marketed incorrectly as a suction filter. For practical instructions on filter installation (see filter installation).

A thermal filtler is very practical. In it the aquarium water is first cleaned, then brought to the correct temperature. One enormous advantage is that you need no extra cable and hence lose no space in the aquarium.

Filter materials: Macrooporous expanded plastic is used for the inside filter (filter cartridge). A coarse filter substrate goes in the outside filter. Filtering charcoal is suitable for "followup treatment" when medication is aqdministered ( see medication_illiness). A number of other filtering materials are used for various purposes or in large filters (small clay pipes, for example). I advise against the use of cotton wadding as a filter because it compresses too quickly (except in combination with charcoal filtration).

Bottom Material

The bottom covering in an aquarium has two functions. First, it is the medium in which the roots of the plants take hold and which stores nutrients for them. Second, it serves as an element of the aquariums's decoration and design.

Quartz gravel with a grain size of 3 to 5 millimeters is an ideal bottom covering. Larger grain sizes are less well suited, because the gravel would pick up too much dirt and is too hard to keep clean. Pet stores carry prewashed gravel, which nevertheless has to be washed again before it goes into the aquarium. Gravel must be neutral--thatis, free from lime--so that the water conditions are not affected. It also should not be too light in color, or it will reflect too much light.

Sand has disadvantages: it decays easily, and plants do not grow well in it. However, for some fish--such as Corydoras and barbs, which like to root in the bottom--you may add a small patch of sand.

A nutritive substrate supplies the aquarium plants with vital substances. Add it to the gravel in the form of a long-lasting fertilizer when you set up the aquarium, or press it in tablet form into the gravel at some later time.

Decorative Materials

Stones and roots are the most important decorative objects in an aquarium. You can use them to create an appropriate environment and provide the hiding places that some fish need (for example, fish that establish a territory, such as cichlids or red-tailed black sharks). Decoration really is a matter of individual taste.

Stones: Suitable for this purpose are all primary rocks--for example, quartz; granite; red, green and black slate; and lava that is free from lime (not sharp-edged; if necessary, break the edges with a few hammer blows).

Roots: You can use oak roots from marshlands (do not take live roots out of the ground) or so-called marsh pine roots. Just don't use roots that come fresh from the woods.

Ceramic and fired-clay caves make the best hiding places and nesting holes.

Backdrop: There are backings with various motifs that can be glued to the pane from outside.

What doesn't belong in an aquarium: The fish can injure them-selves on sharp-edged objects. The following have an unfavorable effect on the water: roots that come fresh from the woods, stones that contain lime, seashells, and coconut shells.

Other Accessories

A thermometer is absolutely essential to control the water temperature. A simple aquarium thermometer is sufficient. Attach it to the pane with a suction cup, offosite the automatic heater.

Time switches are highlly recommended so that you can keep the period of "daylight" constant (12 to 14 hous per day). Thus you are in no danger of forgetting to turn the light on or off.

CO2 fertilliziing devices promote the growth of the plants. I recommend a spray chamber or a CO2 diffuser. These divices, inexpensive and easy to use, keep carbon dioxide (CO2) "on tap." Systems that provide a constant supply of carbon dioxide are not recommended for the beginner, because improper operation can result in an overdose. For a 24-inch (60 cm) tank you need one device; for a 30-inch (100 cm) tank, two are required. They can be arranged side by side (diffusers) or mounted one upon the other (chambers) without difficulty.

Debris vacums are practical for cleaning the bottom material.

An algae magnet or a pane scraper will make cleaning easier.

An oxidizer is a special device that can be used to add oxygen to the water. It does not need to use electrical current and is quite helllpful if you need an immediate remedy when breakdowns occur or the fish fall ill.

An aquarium stand that serves as a base is advisable for laqrge, heavy aquariums. Such a stand is suited by virtue of its design to carry large loads. In addition, you can keep the outside filter and accessories on it.

Tips for Making Your Purchase

• Important in making all decisions that relate to your aquarium: take your time. First, get the aquarium and all the accessories. It is very important to: Set up the aquarium first, then buy the fish three--or, even better, ten--days later. The water needs time to develop into a habitat suitable for fish (see Waiting Period).
• When in doubt, have someone explain to you how the equipment works.
• Don't buy the plants for your aquarium indiscriminately. A plan will ensure that you can create a varied layout in your aquarium. An unbalanced selection of plants with little variety of species can have bad results (see Waste Products).

The Right Location

Thanks to modern equipment that provides sufficient light inside an aquarium, any place in your home can be used. Keep the followiing points in mind, however:

• You should be able to gaze at your aquarium in comfort--perhaps from your favorite armchair.
• There must be enough room available for you to perform comfortably all the tasks necessary to take care of your aquarium.
• At least one electrical outlet should be available near the aquarium.
• For a 24-inch (60-cm) aquarium a sturdy table makes an adequate base. To test its sturdiness, first sit down on it yourself. Larger aquariums are best placed on a special aquarium stand.

Not suitable as locations are window sills (it is too bright and hot there in the summer) and all other places where the aquarium cannot remain year-round.

Shopping List for a 25-inch (60 cm) Aquarium

You can get all the following basic equipment at the same time. Then, wait three to 10 days before purchasing the food and fish. One all-glass aquarium, 24 x 12 x 12 inches (60 x 30 x 30), with or without a frame. One sdtyrofoam sheet 10 melllimeters thick (only if your aquarium has no frame). Six bags of gravel weighing 5.5 pounds (2.5kg) each, with a grain diameter of 3 millimeters, not too light in color. One package of nutrient substrate. Three pebbles or slate stones. One flat pebble or piece of slate. One aquarium root. A water conditioning agent. One liquid fertilizer for subsequent care of plants .

One rotary-pump inside filter with an expanded plastic filler. One automatically coontrolled heater (50W) with a degree scale. One aquarium cover with a built-in flourescent tube (15W), color 41. One backdrop. One aquarium thermometer. One pane scraper (algae magnet). One hose for changing the water, about 5 feet (1.5 m) long and 12 to 16 millimeters thick. One bucket, 2.6-gallon capaacity (10L), to be used solely for the aquarium (label it!) One time switch for the lights. Possibly 1 multiple plug. And don't forget the plants.

Before You Begin

A weekend or a vacation day will be just right for settring up your new aquarium. It takes a fair amount of time. Nothing is more annoying than having to empty an aquarium that has just been set up because you've made a mistake in your haste to get the job done.

Preliminary Work

Before you get started a few chores are necessary.

• Leave the aquarium plants in their packing until you are ready to set them, or put them in a bowl with some water in it (keep them in a dark place). Plants that wilt will not recover.
• Twenty-four hours before the appointed time, put the aquarium root in a bucket of hot water and scrub it until all the bark is removed
• To check whether the tank has survived the trip home and is "water-tight", place it carefully on a level surface (your balcony or cellar floor) and fill it with water. Any leaks will show up quickly.
• After this test, wash out the tank with lukewarm water.
• Wash the gravel thoroughly: fill a bucket one-quarter full with gravel, let water run over it, and ster the gravel with a small hand shovel. Keep pouring out the dirty water and refilling the bucket with clean water until the water is almost complitily clear. When you pour the dirty water into the drain, hold a lartge colander underneath so that gravel will not plug the drain.
• Using water and a brush, clean the rocks. Important: Do not use detergents; the residue can impair the water quality. Lukewarm water is quite sufficient.

The Proper Aquarium Water

Tap water to which a water-conditioning agent has been added is fine for the initial filling of the aquarium. The aquarium first has to be "broken in" with the filter, heater, and lights on, and during this phase the water will develop in the correct way. Only very hard tap water (see Water Hardiness) needs further conditioning (ask your pet store dealer).

If You Have Bought the Fish and the Aquarium at the Same time

If you introduce fish into an aquarium that has not been "broken in", they will not feel at ease and will have difficulty becoming acclimated. Their health can be so seriously impaired that they may die in a short time or waste away over a period of weeks. In addition, the biological processes that are crucial for a healthy aquarium start operating only very slowly. What do you do, however, if--contrary to all good advice--you have bought the fish and the aquarium at the same time, or, as frequently happens, friends beaming with joy come to inaugurate your aquarium , bearing a bag of fish? Then only an emergency aid program will help (see Aid Program).