Algae Control
There are two basic groups of algae:
1. The free-floating types include the green and mustard varieties. They tend to be found throughout the water. While they may cling or settle on surfaces such as walls and floors, they are not usually affixed to them and are easily brushed off. They tend to color a water body cloudy green or yellow.
2. Black algae is the common name or term given to the dark blue-green algae found growing on pool surfaces. Black algae growth in localized areas such as along one wall, in the deep end, in a corner or around obstacles such as steps indicates an area of poor circulation.
The most common cause of irritation for pool owners is water that is green and cloudy. It is the most obvious sign of something gone wrong in pool maintenance. Proper maintenance will not only keep your water looking great, but also allow for easy prevention of algae growth.
The growth of both types of algae can be easily prevented by using a quality algaecide as part of a regular maintenance program, and by proper circulation and filtration. It takes far less algaecide to prevent algae growth from getting started than it will to cure it once it has occurred. The regular use of algaecide is also recommended to prevent problems, should a failure of the sanitization program occur. Due to the volatile nature of chlorine or bromine, these residuals can often be lost very quickly in pools due to equipment or operator error or by heavy rainfall or bather waste demand. If this occurs without an algaecide present, the rapid growth of algae can occur in a few hours. However, if an algaecide is present, it will act as algae growth prevention until the sanitizer system is functioning normally.
In spite of our best efforts, algae problems do occur and require some consideration for proper treatment. When an algaecide becomes necessary, the following factors need to be considered before treatment:
- The number of algae present. It is critical that sufficient algaecide is added to treat all of the algae at one time. The use of only some of the needed algaecide will not kill some of the algae. Ideally, have an active algaecide present that only needs to be topped up every week or so. It is important to follow the directions for use on the package.
- Age of the algae. The older algae becomes, the more difficult it is to control. Treat the problem as soon as it is noticed.
- Sunlight and water temperature. It is best to treat when algae are actively growing. Sunny days and a water temperature of 60ºF or higher will be helpful.
- Type of algae. Different types of algae require different types of treatment.
GREEN ALGAE
The most common algae associated with swimming pools is green algae. It is very opportunistic, meaning it will take advantage of any failure in the normal sanitizing program and quickly infest a pool. One will see green algae problems frequently appear overnight following heavy rainstorms. This is because rainstorms, especially those with lightning, actually provide food for the algae in the form of nitrogen. The nitrogen not only feeds the algae but also destroys chlorine residuals by forming combined chlorine. Green algae must not be mistaken for problems with copper content in the water. If high levels of copper are present, the water will become a clear green, whereas green algae will cause a cloudy green appearance. The best way to treat for green algae is to prevent it in the first place. Use an algaecide regularly as part of a normal maintenance program. This will prevent algae from growing, even if a failure in the sanitizing system was to occur. It is always easier and more effective to prevent the algae problem than to try and eliminate it once it occurs. When it does occur, treat it promptly. The longer the wait before treatment, the more difficult and costly the result. Select an algaecide that will both treat the existing algae and prevent renewed growth. Follow the label directions and maintain circulation during treatment.
YELLOW OR MUSTARD ALGAE
The yellow or mustard algae is very similar in form to the green algae, but is much slower growing and is deficient in chlorophyll (green pigment) which accounts for its yellow color. Because yellow algae grow very slowly, it is also very difficult to destroy. By the time you see it growing in your pool, it has likely been there as long as several weeks. Additionally, since yellow algae is low in chlorophyll which is light-loving, the algae live and even grow in dark areas of the pool such as plumbing and filters. This only compounds the difficulty of control. Care in selection of a proper algaecide is most important. Be certain to select a product made for the control of this unique form of algae. Copper-based algaecides seem particularly well suited for controlling yellow algae, but others, including recently developed synergistically blended products, are also effective. One word of caution: it is not unusual to need to treat yellow algae more than once to bring it fully under control. This again points out the value of preventing the growth in the first place.
BLACK ALGAE
It is considered the most difficult algae to control. However, it is also likely the easiest to prevent. Black algae typically gain a foothold in areas of the pool that suffer from poor circulation. Areas such as corners or in certain areas of the deep end are often identified as places where black algae continue to show up in a particular pool and are then nearly impossible to eliminate. Most often, these areas suffer from inadequate circulation and thus little or no fresh water, sanitizer or algaecide gets to the area with any regularity. One of the best ways to prevent black algae growth or eliminate it once it surfaces, is to correct the circulation problem.
Once it begins forming, black algae develops specialized cells that lock it deep in the pores of pool surfaces. In order to effectively control it, all of its cells including those deep in the surface, must be killed. It is all but impossible for chlorine alone to get this deep into the pores of the pool’s surfaces. In addition to the attaching or locking mechanism of black algae, the growing colony also produces a defense mechanism. Outer layers of the colony produce a waxy coat that prevents chlorine or algaecides from penetrating into the colony and killing it. Therefore, the algaecide used should contain a “penetrating” agent. This agent will actually work to help the algaecide penetrate into the pores of the pool surface and cut through the waxy coat with a special wetting action that chlorine does not have.
The following steps will help in bringing black algae under control:
1. Correct any problems with the circulation pattern in the pool.
2. Brush the colonies as this will break through the waxy coating protecting the colony.
3. Add an algaecide intended for use on black algae.
4. Brush the colony daily thereafter, if possible, as this will remove any dead cells from the surface exposing the living cells underneath for exposure to the algaecide.