After brushing the area(s), the next step is to chemically treat the surfaces, as well as the water, to rid the pool of the algae. One of the most effective treatments involves using granular trichlor on the pool’s horizontal surfaces and a copper-based broad spectrum algaecide for the vertical surfaces, in addition to the pool water. This process first involves a trichlor treatment then, after the chlorine level recovers and the water is balanced, a copper-based algaecide is applied.
Broad spectrum chelated-copper algaecide can also be used as a preventive measure. Some copper algaecides are triple chelated and will protect the pool for months at a time, giving a service technician the ability to effectively brush and remove black algae, layer by layer.
It is always a good idea to have the water tested for metals prior to the addition of any metallic algaecide to be sure there is not any non-chelated metals from the pool equipment or source water present. If metals are in the pool water prior to the addition of a metallic algaecide, the water can become oversaturated, which causes problems such as staining and or water discolouration.
In the case of black algae, it is extremely important to always vacuum or brush and backwash/clean any remnants of the algae heads that have been brushed off to remove them from the system. Brushing is important to controlling this algae because of its ability to form a protective layer, making it resistant to chemical treatment. Further, any remnants of the black algae that remains in the pool can regrow into new problem areas; therefore, to keep it under control, it is important to maintain a higher parts per million (ppm) of chorine along with using a broad spectrum copper-based algaecide.
Yellow/mustard algae
Yellow/mustard algae may be one of the most difficult a service technician may face. One reason for this is because it is often misdiagnosed—sometimes it is mistaken as green algae and in other cases as pollen, or just dirty pool water.
Yellow/mustard algae in a blue pool will make the water look green, so it is important to ask the right questions and be sure about any observations before making a diagnosis. To eliminate the possibility of misdiagnosing yellow/mustard algae as green algae, the first question to ask the homeowner is if their pool water is cloudy. If the answer is “no,” then it is likely not green algae as it makes the pool water cloudy and murky.
| The factors of algae growth |
|---|
| • Photosynthesis (sunlight): Algae is a plant and like plants it is able to take light and generate its own food source for growth. |
| • Organic materials: Leaves, barks, seeds, and grass clippings can introduce algae into the pool water. |
| • Rough surfaces: Algae loves to have something to cling to on the surface. It is very difficult for algae to get a foothold on smooth surfaces. |
| • High-iron content: Some studies have linked the presence of iron in water to an increase in the intake of carbon which makes algae grow more rapidly. |
| • Lack of chemical maintenance: Zero chlorine in the pool water combined with a hot summer day may result in algae within as little as 24 hours. |
| • Poor filtration or circulation: Water that is moving and being cleaned of particulate debris is much less likely to produce algae. Poor filtration and little to no water movement are two of the biggest causes of algae growth—even in chemically maintained pools. |
