Swimming pools that are open for regular use only undergo complete water changes during major repairs, primarily for two reasons: the high cost of water replacement and the impact frequent changes can have on the structure and settling of the pool. So, how should we address algae problems in our swimming pools?
Treatment Methods for Pool Green Algae
Step 1: Improve circulation to address small clusters of algae.
If the algae are only forming small clusters and have not spread to other parts of the pool, this might indicate the presence of stagnant water areas. At this point, it’s important to check if the water jets are functioning properly. The jets should be angled to direct water towards the surface in a spiral movement.
Step 2: Use flocculants to cluster the algae.
Flocculants or coagulants can gather the algae together, allowing them to be vacuumed up. This may take a day, but by the end of this process, the pool should be clear again. This is the fastest method to clear the pool, but swimming in the pool during this process is not safe. If algae can reproduce, so can viruses and bacteria. Therefore, it’s necessary to disinfect the pool with algaecides and avoid swimming until the chlorine levels and pH have returned to normal.
Step 3: Treat the pool with algaecides.
Algaecides can certainly kill the algae in the water, but several factors should be considered when using this method:
Some algaecide products may not be effective against existing algae clusters, especially black algae. It’s advisable to consult with pool supply store staff or find a product with an active ingredient concentration above 30%.
Quaternary ammonium algaecides are inexpensive but can cause foaming in the pool water, which many find undesirable.
Copper-based algaecides are more effective but also more expensive and can stain the pool walls.
After adding algaecide, wait at least 24 hours before adding other chemicals.
Preventing Algae
Step 1: Maintain the pool water.
Keeping the pool surface covered with chemicals should prevent algae growth. Regularly test the water for free chlorine levels, pH, alkalinity, and cyanuric acid. The earlier problems are detected, the easier they are to solve. Ideally, testing should be done daily, especially in the weeks following an algae bloom. During the swimming season, tests should be conducted at least twice a week.
Step 2: Use algaecides as a preventative measure.
When the pool is in normal condition, it’s best to use algaecides in small doses weekly. This can kill algae before it has a chance to grow. Follow the instructions on the product label strictly and adhere to the regular prevention guidelines to avoid letting algae proliferate. Overusing algaecides can contaminate the pool or cause foaming.
Step 3: Remove phosphates.
Algae feed on several nutrients in the water, especially phosphates. Phosphate test kits are an inexpensive way to check for these chemicals in the pool. If phosphates are detected, purchase a commercial strength phosphate remover from a pool supply store. After two days, remove the phosphate remover with a filter and either a mechanical arm or a manual vacuum cleaner. There’s some debate among pool experts about safe levels of phosphates, but unless algae problems recur, 300 ppm should be low enough.
Considerations for Removing Pool Algae
Heat and sunlight can break down chlorine and promote algae growth. During hot, sunny weather, closely monitor chlorine levels.
In winter, use a mesh pool cover to prevent debris from entering the pool while allowing water through.
If possible, add 70% of the recommended amount of pool chemicals at first, and if necessary, add the remainder a few hours later. This reduces the risk of exceeding recommended levels but makes further adjustments more challenging.
Throughout the process, closely monitor the pool filtration system. Thoroughly backwash or clean the filter whenever the pressure exceeds the normal operating pressure by 10 psi. Dead algae accumulated in the pool filter can quickly dirty the filter, necessitating frequent cleaning.
