Algae is a common problem in swimming pools. What is it; what are the different types & how is it successfully prevented and treated. First of all, algae is a single-celled plant form. Some are aquatic (live in water), some are not. Algae utilizes the process of photosynthesis to manufacture its own food. Algae comes in very wide variety of colors and forms making it adaptable to almost any condition. Although some forms are virulent – especially Black or Mustard algae -, most are harmless and pose no more than a nuisance to most pool owners. Due to algae’s microscopic size, it takes literally millions of these plants to accumulate to be noticed by the naked eye! By that time it may be too late and very costly to correct. Prevention of algae blooms is the best solution.
Green Algae: The most common form of algae that we deal with in swimming pools is “green” algae. Green algae (varies in color from blue-green to yellow-green to dark-green) can be free floating in the water (turning the water a hazy-green) or can be wall-clinging (patches of green). Wall-clinging varieties range in severity from small patches on pool walls and bottoms to virtually covering the entire pool surface. Green algae has the ability to clog filters and may even cause surface damage if left untreated. Green algae can be treated fairly simply and quickly with a proper, aggressive shocking & algaecide.
A relative of regular green algae is “small-celled green algae” (SCGA). The difference is seen in these areas: 1. The water remains relatively clear. Many treat the problem (without proper analysis) as a copper or mineral problem, however the metal chelants will show no effect. 2. When treating with chlorine, chlorine seems to “disappear”. SCGA is very resistant to even high levels of chlorine.
Other mid-summer types of green algae noticed is “green spots” all around the pool, especially in shady areas. The water is almost always “very clear”. The water can have a “stinging” sensation. This is normal green algae, typically brought about by lack of homeowner care; i.e. not following a weekly maintenance routine such as the Once-a-Week 3 Step program combined with very low pH and very low Total Alkalinity.
Treatment: Have water properly analyzed. BALANCE THE POOL WATER. Pools treated with chlorine or bromine should aggressively shock with chlorine (BioGuard Burn Out® or Smart Shock®) and use a good quality algaecide such as Back Up®, Algae All 60®, or Banish® in extreme cases. Pools treated with SoftSwim or other Biguanides should top up their Bactericide level “B”, add a double dose of algaecide “A”, and add a double dosage of shock or “C”. Follow up either method with Optimizer Plus® (a borate product similar to ProTeam Supreme). Treating algae with Sodium Bromide should be discouraged (sodium bromide treatments, can, in time, cause a chlorine demand problem).
“Black Algae” (actually blue-green algae) forms in cracks and crevices on pool surfaces, especially plaster finishes. We normally find black algae growing in, but not limited to, shady areas of the pool. Black algae is more typically found in concrete or plaster finished pools; it is very uncommon to find it in vinyl liner pools. It is known for a heavy slime layer and “skeletal growths” that make it impervious to normal chlorine levels. When viewed in a swimming pool, the water remains relatively clear, however, almost all customers notice a high chlorine demand (use much more chlorine than normal). When brushed, “black algae” will be difficult to budge and even though it seems as if it has been removed, the black algae will most likely return to the exact same spots within 24 hours.
What we’re beginning to understand is that Black Algae is “aided” by swimming pool bio-films. As bio-films accumulate on pool surfaces, they act as a kind of “breeding bed” providing nutrients and a “soft” place to set down roots. Removal of the bio-film dramatically aids in the long term treatment of Black algae. The more that the bio-film is removed and continually removed, the less likely Black Algae will be able to set down.
Treatment: Have water properly analyzed. BALANCE THE POOL WATER. Prior to and during treatment, the algae MUST be thoroughly brushed in order to “break open” the slime layer that covers and protects the Black Algae cell. During treatment, the chlorine level MUST be maintained in excess of 3.0 ppm – this may require daily shocking of the pool – AND the affected areas MUST be thoroughly brushed 2 to 3 times per day to allow the chlorine treatment to penetrate the algae. TRUE Black Algae is very resistant to treatment and can be transferred from pool to pool via bathing suits and pool toys. Failure to do these critical steps will prevent the treatment from working. Pools treated with chlorine or bromine should aggressively shock with chlorine (Burn Out® or Smart Shock®) and use a good quality algaecide such as Back Up®, Algae All 60®, or Banish® in extreme cases. Pools treated with SoftSwim or other Biguanides should top up their Bactericide level “B”, add a double dose of algaecide “A”, and add a double dosage of shock or “C”. Follow up either method with Optimizer Plus®. Treating algae with Sodium Bromide should be discouraged as mentioned above.
“Mustard Algae” is probably the MOST misdiagnosed form of algae. Mustard algae is a chlorine-resistant form of green algae (yellow-green to brown in color) typically found in sunbelt areas. It often resembles dirt or sand on the bottom or sides of a pool. In our market area (Fairfield county CT), the number of TRUE Mustard Algae cases that we treat can be counted on ONE HAND in most seasons. Mustard Algae is prevalent in Sunbelt areas. Mustard Algae has certain characteristics: It can be brushed away very easily, but returns quickly to the same location.
Keep in mind that the “algae” may be returning to the same place due to a dead spot in the pool. Be sure that you have good circulation through out the entire pool.
Although it usually creates a large Chlorine demand, it has been known to survive in high levels of Chlorine – over 3.0 ppm. It is extremely important to remove mustard algae growth from equipment (including the back of underwater lights & ladders) and bathing suits to avoid cross or recontamination of other pools. Pool equipment can be left in the pool during product application or cleaned separately with a mild cleaning solution. Rinse thoroughly if equipment is used in a SoftSwim® pool. Bathing suits should be washed with detergent as directed on garment label.
Treatment: Have water properly analyzed. BALANCE THE POOL WATER. Prior to and during treatment, the algae MUST be thoroughly brushed in order to “break open” the slime layer – such as with Black Algae. Failure to do this critical step will prevent the treatment from working. Pools treated with chlorine or bromine should aggressively shock with chlorine shocks such as BioGuard Burn Out® or Smart Shock® and use a good quality algaecide such as Back Up®, Algae All 60®, or Banish® in extreme cases. Pools treated with SoftSwim or other Biguanides should top up their Bactericide level “B”, add a double dose of algaecide “A”, and add a double dosage of shock or “C”. Follow up either method with Optimizer Plus®. Treating algae with Sodium Bromide should be discouraged as mentioned above. Click here for all Algae treating products.
The best way to prevent and control algae is to maintain good pool care. Good pool care means following the 5 Keys to pool care (look for our published articles on theses subjects): 1. Have and maintain good circulation of the water to all parts of the pool. 2. Filter the pool a minimum 8 to 12 hours daily. 3. Clean the pool regularly by vacuuming and brushing all surfaces. 4. Test the Water at least 2 times each week. Testing tells you what is going on with the water. Make adjustments immediately when necessary. 5. Maintain good Water Chemistry. Chlorine or other sanitizer in their correct ranges, pH 7.4 – 7.6, Total Alkalinity 100 – 150 ppm, Calcium Hardness 200 – 300 ppm. On a weekly basis (every week all season long): Shock the pool with the appropriate shock treatment and add a maintenance dose of a good quality algaecide (please don’t use the gallon jug algaecide – they’re mainly colored water).