Algaecides
The chemistry of algaecides is complex, because 46 species of clean-water algae exist. Some algaecides work better on one kind of algae than on another.
Planktonic clean-water algae float on the surface. Other types attach themselves to rough spots on the pool walls and floor and are very difficult to remove. Clean-water algae may be blue-green, red, brown or black and can cause tastes, odors, turbidity and slippery spots, as well as increased chlorine demand.
Sunlight, temperature, pH, bacteria, chlorine residual and the mineral conte nt of the water affect the presence and growth rate of algae. Algae can be introduced to a pool by wind-borne debris, rain and falling leaves, or they may be present in the source from which the pool is filled.
Preventing algae growth by chlorination is us ually not a problem, but removing existing algae from a pool can be difficult. If algae get a firm start on the side or bottom of a pool, draining the pool is sometimes more practical if the local water table is not too high to allow it. The pool should be thoroughly washed down with a chlorine solution.
Sunlight is necessary to the growth of algae, so it is a much greater problem in outdoor pools. If not controlled, algae can spread rapidly, turning an entire pool dark green in as little as a day or two.
Pools that consistently maintain a high free chlorine residual concentration are seldom troubled by algae. Maintaining free available chlorine and superchlorinating are the best preventative measures. Combined chlorine is not as effective as free chlorine in preventing algae growth, and bromine and iodine are even less effective.
An algae inhibitor is a commercial product that acts as a penetrating or wetting agent to allow the chlorine to be more effective. Algae inhibitor is said to control all types of algae growth and provide a stable backup system to chlorine. It is not pH sensitive, does not evaporate, concentrates on surfaces of the algae and is a powerful wetting agent.
