Scrub your aquarium with practically any preparation that cuts dirt well for you in other household jobs, and rinse it thoroughly before putting it back into service. Accumulated dirt and algae on the sides are best removed by scraping with a razor blade, then scrubbing with soap or detergent and water, with or without ammonia added.

Use a plastic or copper sponge on the stubborn spots. Do not scour with sand or other abrasive, as this in time will dull the glass with hundreds of minute scratches.

Whatever kind of an aquarium you have and wherever you place it, the water will eventually take on a greenish color, the result of the

All About Aquariums 193

growth of millions of tiny aquatic plants, mostly algae. How did the algae get there? They could have come in the front door, through the screen of an upstairs window, or ridden in on your shoulder

The air around you at this moment contains countless suspended spores of many kinds of plant life, each searching, as it were, for a combination of circumstances which will allow it to settle down and raise a family. The spores that fall and grow upon the moist face of a rock in dark, damp woods become moss. Those that settle on damp clothing and raise blotchy 1ooking colonies we know as mildew. Others form mold on unprotected food. Some of the spores that fall into your aquarium and pool are those of algae, one of the more spectacular growers among spore-borne plants.

A certain greenness in the water is desirable. In an outdoor pool you can test the water for proper coloration, as I have suggested, by holding your hand about 12 inches below the surface. If the outline is barely discernible at that depth, the color of the water is perfect, indicating a good balanc.

Algae can develop to a point where they cease to be a blessing and become a nuisance. However, too much algae become unsightly before they are dangerous to fish, so if you ever have to deal with them there will be plenty of time to do so. When the aquarium water becomes practically opaque, try to find the cause.

An overcrowded aquarium is often the answer. Double-check the number and size of fish you have, and make sure your capacity calculations were correct. If overcrowding is the cause, the situation will right itself soon after a few fish have been removed.

Too much sunlight is another cause. Remember that the aquarium should get direct sun for only two hours a day. If it is getting more than two hours, and algae are too numerous, try cutting down the strength of the light by pasting white or colored tissue paper over the sunny side of the aquarium.

To kill algae, remove snails and tropical fish from the aquarium and drop in a bit of "fines" potassium permanganate. Figure the capacity of the aquarium water in cubic inches, divide by 231 to get the capacity in gallons, and allow 1/8 grain tablet to 1 gallon of water. Leave aquatic plants and goldfish in the aquarium during the treatment. It will do them good. The potassium permanganate will color the water purple. This will fade to lavender, to pale brown, but finally the water will clear. Excess algae will be gone, but will return if the situation which caused them has not been corrected.

Dealers in goldfish sell algae-killing preparations, but these are no better than the straight potassium permanganate treatment.

Keep your eye on any aquarium with an exceptionally heavy growth of algae, for under such circumstances the water will often undergo a chemical change which will kill off the whole algae mass. Once they begin to die, turning brownish yellow in the process, there is no stopping the process. Change the water immediately, for decomposing algae generate gases that kill goldfish.

If the chemical change takes place during the night, the goldfish will be pretty sick by the time you spot trouble in the morning. The change to fresh water will soon revive them

Cloudy water in an aquarium, unless it is extremely overcrowded, is caused by only one process-decomposition. There may be a dead fish or snail, or accumulated bits of food. If cloudy water doesn't smell sour by the time you notice it, it soon will. There is only one way to correct it and that is to change the water.