Youngman, Age 14, Of Indianapolis, Ind.,  for his question;     

What causes algae?     

From time to time, the water in a goldfish bowl becomes fuzzy with clouds of floating algae. Murky clouds of algae also cloud reservoirs and swimming pools. We clean the water, and new colonies of a1gae arrive from who knows where. Perhaps if we know what causes these plants to form, we can discourage them and cut down on our cleaning chores.

A1gae are members of the plant world and therefore made up of living cells. And all living ce11s come from other living cells, for all the teeming forms of life are handed on from one generation of cells to the next. An oak tree grows from an acorn, which is the seed of a parent oak tree. A sugar cane may grow from a  joint in the stem of a parent sugar cane.     The alga plants have no stems, no roots, no seeds and no flowers, and most of them live in the water. They include a vast assortment of seat reeds from microscopic Diatoms to giant kelps go feet long. Pond scum and various fresh water plants are also a1gae. Many algae are single ce11s too small for our eyes to see as individuals.     But teeming throngs of these floating microscopic plants tinge the seas and fresh waters with green or greenish blue, with brown or rusty red. Some alga cells multiply by dividing in two. Some algae produce buds, and strings of daughter ce11s cling together in colonies. And some a1gae produce spores or seedlets which develop into a new generation. Certain one celled algae of the ocean spend months in the spore stage. The spores are much sraaller than the swarming plant ce11s that tinge the water. The tiny spores are invisible without the help of a microscope.     Alga spores and single ce11s of microscopic algae are present in almost every drop of pond water. Too small to be seen, they teem in bodies of fresh water. A few spores or alga ce11s nay be in the freshwater you put into an aquarium. Others may be stuck to the glass or lurking in cracks. These microscopic specks of life are just waiting to use sunlight and dissolved chemicals to sprout forth a new generation of Algae.     Algae thrive in stagnant, sunny water and develop more slowly in shady, wel1 drained water. Traces of copper sulphate, sodium arsenite or other chemicals added to the water may discourage the spores and destroy the algae. But read the directions before using such a preparation, and follow them strictly. Too much may spoil the fresh quality of the water ox kill off the fish along with the algae.