Scum consists also of countless millions of tiny suspended vegetable organisms, thriving on the manure, in solution, which has been let loose in the water. These organisms, to a large extent, are various forms of algae. They will be ever-present-and welcome-in your pool. Part of the scum quite possibly may be fish food. If you are a new water gardener, you probably will feed your fish too much, and excess food will remain in the pool to decompose.

Suprising1y enough, one of the principal factors contributing to the scum will be plenty of sunlight. The foliage of water-lilies and of floating and submerged plants in a newly planted pool takes a few days to spread. As it spreads, it kills out the microscopic plant life in two ways: First, it competes for food in suspension in the pool water; second, it produces more and more shade as it spreads, and in shade the microscopic plants cannot multiply or even hold their own.

So you must remind yourself that within the course of the few weeks it took you to set up your water garden, you have been aiming at a balance of life which it takes nature months and years to establish. If you have goldfish and submerged plants in the pool, in addition to the showy plants, the pool will soon find its own balance and hold to it.

Now that you know what causes the scum, it is an easy matter to get rid of it. Simply raise the water level of the pool by a quarter of an inch.

The floating scum, with a little guidance from you, will run off down the overflow drain. If the pool does not have an overflow drain, sweep the scum to one corner with a folded newspaper or a broom and dip it out.

Healthy pool water is not crystal clear, but has a slightly cloudy, greenish tinge. This green cast is due to the millions of suspended microscopic algae, plankton, and similar plants, which are necessary for the health of the goldfish. It is easy to determine the proper balance of these plants in the pool water. Roll up your sleeve and hold your hand about 12 inches below the surface. If your hand is barely discernible at that depth, the balance is perfect.

As for crystal clearness, remember that you will not see the water of a pool as you see water in an aquarium. At the vantage points from which you will enjoy your pool, you will not see into the water at all, save for glimpses of the darting goldfish. What you will see will be reflections of water-lilies, of border plants, and of the sky.