→ Algae is the most common issue for pool owners, and with the season winding down it is the perfect time to get ahead of the problem.
While algae is typically associated with the summer months, it can still thrive in a closed pool, particularly under the right conditions—such as stagnant water, low chlorine levels, sunlight exposure, and the presence of debris or runoff.
→ Let’s dive into the key reasons algae blooms when pools are closed:
→ When you close your pool, circulation typically stops due to the systems being dormant, which allows water to stagnate. Without regular flow and filtration, algae has the perfect environment to attach to surfaces and begin growing.
→ Additionally, without proper circulation, the pools chemicals—such as chlorine—are less effective at combating algae. This is your pools first line of defense against algae and bacteria, and even if you properly chlorinated your pool before closing; chemical levels will naturally diminish over time due to a variety of factors.
→ The key factors that fuel its growth is sunlight. The sun rapidly degrades chlorine, making the pool’s ability to sanitize the water impossible and creating an environment where algae can thrive.
→ When closing the pool, we all know it’s crucial that all debris—leaves, dirt, and other materials— are removed. Leftover organic matter can break down in the water, releasing nutrients like phosphates and nitrates. These enter pool water primarily through debris, runoff, and even some chemicals, and act almost as a fertilizer for algae.
How to Get Rid of Algae When Your Pool is Reopened
→ If you’re tackling algae as you open the pool for the season, we have you covered. Here are some key steps to prevent it from multiplying:
→ Before addressing the algae, check your pool cover for any tears or areas where debris may have accumulated.
- A faulty cover can contribute to algae problems. Ensure your cover is intact; small tears can be easily repaired, but if left unchecked, they may require a full replacement.
Use a leaf net, or pool skimmer to remove any large debris from the surface, vacuum any debris that has settled to the bottom.
→ Balancing the water chemistry will prevent algae from continuing to grow! Use a pool test kit, or test strips to check the following levels: Alkalinity, pH, CYA (Cyanuric Acid), and FC (Free Chlorine). If any levels are off, add the necessary chemicals to bring them back into balance, then let the water circulate before moving to the next step.
→ Algae, depending on age, tend to attach to surfaces in the pool. Brushing these surfaces will help loosen the algae, allowing the chemicals to work more effectively. Focus on walls, floor, steps, corners, and ladder rungs.
→ Shocking the pool is also a process called super chlorination, it is an effective way to kill algae quickly by raising the chlorine level to a much higher concentration, and it should only be used when algae is present.
What to Do:
Follow the instructions on the shock for the correct amount based on your pool’s size and current FC levels. Some may require prior mixing, and others can be scattered directly from the bag.
Walk the perimeter of the pool at least once whilst adding the shock, this is to avoid concentration in any one area.
→ After shocking the pool, it’s essential to run the pool filter for an extended period (typically 12 hours, or overnight). The filter will help remove dead algae and any other debris that’s floating in the water. If you still see visible algae or debris, use a pool vacuum to clean up the remaining particles.
→ As your pool filter works to remove algae, it may become clogged with debris. If you notice the PSI is higher than normal, backwash your filters and empty the skimmer baskets for the pool and your pool motor.
For cartridge filters, remove the cartridge and rinse it thoroughly with a hose.
For sand or DE (diatomaceous earth) filters, follow the manufacturer’s instructions for backwashing.
Repeat this process once the algae has been cleared.
→ Once you’ve tackled the algae, maintaining your pool is key to preventing future outbreaks. Regular maintenance will help keep your pool clear and algae-free.
Test your water weekly to ensure the chlorine, pH, alkalinity, CYA, and calcium levels remain in balance.
Skim the surface daily, brush the walls weekly, and vacuum as needed.
Run the filter daily for 8–12 hours to maintain proper water circulation. During the summer months, you may need to run the filter for longer periods due to increased pool use.
Consistent maintenance and attention to water chemistry are key to keeping your pool clean, healthy, and ready for swimming all season long!