What is a Balanced Aquarium?

Originally the concept of a balanced aquarium was that the standing aquarium is a self-contained microcosm - a little world. The theory ran that as the plants manufactured food through the process of photosynthesis; they utilized carbon dioxide and gave off oxygen. Fishes, on the other hand, gave off carbon dioxide and utilized oxygen. Fishes’ waste, according to the theory, fertilized the plants, while excess plant growth provided food for the fishes. One thing thus balanced another, and no outside care was required.

Unfortunately this theory simply does not hold up in practice. While plants do give off oxygen in excess of what they use for respiration, they do so only in the presence of bright light. When the aquarium is dark, they use up oxygen just as do the fishes. Water cannot store more oxygen than the amount required to keep it in equilibrium with the air above it. Excess oxygen passes off readily. The same does not hold true of carbon dioxide. It tends to stratify, forming layers along the bottom. (Circulation prevents this stratification.) Having a maximum air surface in proportion to the depth thus goes a long way toward keeping the aquarium properly “balanced.”

The waste matter produced by the fish is far in excess of the amount required by the plants. Moreover, most of our aquarium fishes are carnivorous, eating animal, not vegetable, matter. Even the more herbivorous species require some animal food.

So the idea of a “balanced aquarium” is a fallacy in its original concept. An “aquarium in balance” is, however, what can be achieved.

The factors that modify an aquarium more or less balance each other includes the proper amount of light (too much over stimulates algae, too little does not permit plant growth); the proper amount of food (too little stunts the fishes, too much pollutes the aquarium); the proper number of fishes; the correct size of aquarium, and the proper temperature, etc. All of these things must be in proper “balance” with respect to themselves and the others if the aquarium is to flourish.

What is the best way to light an aquarium?

The aquarium should be lighted from the front and the top. The rays of the light should be directed down and back toward the rear, bottom. They should be directed away from the viewer’s eyes, striking the fishes directly to reveal their beauty. Light coming from the rear tends to silhouette the fish and to conceal refractive colors.

As a general rule, eight to ten hours of light a day, utilizing the wattages given, will result in satisfactory plant growth. Larger wattages may be used for lesser periods of time, and smaller wattages for greater. That there is a point of diminishing returns is obvious. Too low a wattage will not penetrate a depth of water; too high a wattage may overheat the upper layer of the water. Observation over a period of time will determine the most satisfactory wattage to use and the proper period of time to keep the lights on.

The most satisfactory arrangement is one that keeps the plants healthy and the algae growth down to a minimum. Should the plants start to deteriorate, usually more light is required; that is, higher wattages or a longer period of illumination.

Excessive growth of algae usually indicates too much light and, possibly, an excess of decomposing organic matter. The remedy, usually, is to decrease the amount of illumination and to siphon off all excess food and foreign matter. A certain amount of algae is bound to form even under ideal conditions. But you can keep this minimal growth in check by scraping and by using scavengers. You should be most concerned with the wild, seemingly uncontrollable growth that coats the rocks and plants and turns the water green.

Certain colors, although pretty to see, actually inhibit the growth of plants. The warmer tones at the red end of the spectrum are the most satisfactory for plant stimulation. Blue colors are the least helpful. The most practical are the uncoated clear glass bulbs which have a long filament. Although there are a number of inexpensive bulbs on the market which have short filaments, actual tests have proven them to be less effective than the long in stimulating plant growth. Any coating on a bulb must of necessity diminish the amount of light reaching the plants and thus decrease the effectiveness of the bulb.

What is a cover glass and how does it fit?

A cover glass is an aquarium cover. It is best made of light plate glass so as to be more break-resistant. When used with a reflector, the glass should start from just behind the reflector and cover the balance of the tank. Under no circumstance should the cover glass be extended under the incandescent reflector. The heat of the bulbs is likely to crack the glass. Also, the glass coming between the light and the tank may filter out a good deal of the light and retard plant growth. With a hood, no cover glass is necessary.

The rear corners of the cover glass may be cut out for a heater and/or filter. There are clips and handles available which can be fastened in place to suspend the cover glass inside and just below the rim, rather than having it rest on the rim of the tank. These are helpful because they prevent moisture from gathering between the glass and tank rim and corroding it.

When neither reflector nor hood is used, a cover glass should protect the whole aquarium. The functions of a cover glass are many. It helps regulate the temperature, prevents fishes from jumping out, reduces evaporation, keeps out dust and dirt, and also keeps out inquisitive fingers and paws !

For a tank kept in a sunny or extremely light location, the cover may be of translucent glass to cut down the glare.

For proper aquarium heating, you need a source of heat that can be regulated. The heat given off by the reflector is incidental. Most people turn their reflectors on in the evening when the house is at its warmest and turn it off when they go to bed. Should they be dependent solely on the reflector for heat regulation this would result in the tank temperature being at its peak during the evening and plunging rapidly down during the night, when the light and usually the central heating system are both turned off. This could be disastrous. Unless you are prepared to keep a close watch on your tank thermometer, turning on the light as the temperature drops and turning it off when the heat rises, you cannot depend on the reflector. Actually, you would be turning yourself into a thermostat. It is much more practical to buy one.