When you test and add pool chemicals to your pool, you use test kits to determine the recommended amounts of chemicals your pool is calling for. These chemicals are added in advance to handle the anticipated pool bather, dust and bacteria loads for the coming week. From servicing your pool every week, you can get to know how your pool may react to certain chemicals and or conditions. However, you still cannot predict all the variables. Because of this, sometimes algae could appear on your pool surface or in your pool water. Please review the following list of algae types and ways to alleviate them:
Yellow Algae- It usually appears as yellow-green patches on the walls of your pool. This type of algae tends to be a seasonal problem and if it is just brushed away, it will come back week after week. Inadequate circulation and filtration is a common contributing factor and sand filters are the least effective at removing this very fine algae out of your pool. Special chemicals have been developed especially to fight this yellow algae and if added, will usually solve the problem for the season. (yellow algae usually comes back each year)
Green Algae- It usually appears as green water color and/or green on the walls and floor of your pool. It is most commonly caused by insufficient chlorine but filtration and circulation are a major factor as well. A strong chlorine liquid or shock chlorine added to the pool and additional filters run time usually take care of this algae.
Black Algae- I t usually appears as round, black spots on the surface of your pool. It will also attach itself to the rim of your light fixture and in “rope clip” indentations. Lacks of chlorine or circulation are the cause of this type of algae. Black Algae builds a protective coating over itself that allows it to survive in chlorinated water. This protective coating must be scraped off and special chemicals added to remove this type of algae. (This type of algae, if not totally removed, could go dormant and reappear at low chlorine levels.)
Algae at the water line- The sun heats up the top few inches of water on the pool during the day. The lack of chlorine and moister that occurs above the water can encourage algae growth. Sometimes running your pool during the heat of the day can alleviate this problem. Direct contact with a chlorine tablet will remove black and green algae, even off the stubborn pebble type water lines.
Algae in attached spas- Similar to the water line problem, the small body of water in a spa heats up much faster than the pool during the day, therefore, depleting it of chlorine. If the spa exchanges water with the pool, run you pool during the heat of the day so as to keep the water circulating. An additional chlorine float with tablets could be added to the spa water.