Algae growth is stopped at temperatures below 40° F, but some algae can continue to survive, and like weeds in a lawn, can go dormant over the winter, coming back to life in early spring, weeks before you open the pool.
That's because hot weather heats up swimming pool water where it then increases evaporation, depletes chlorine levels and messes with pH levels – all of which creates the perfect environment for algae and bacteria to grow.
Pool algae occurs for many reasons. Low or inconsistent chlorine levels, faulty pool filtration and poor water circulation may be to blame. Preventing pool algae from flourishing helps to keep your pool operational so you can enjoy it all season long. The key to an algae-free pool is regular maintenance.
It is best to close your pool when the temperature of the water is consistently below 60 degrees. Once the water temperature drops below 60 degrees, microorganisms and algae cannot grow and become dormant for the winter season.
If your pool has been green all season you're probably super excited to close it. While it seems like the easiest option – it's not! It's much smarter to close your pool as clean as possible. Algae can grow in water as cold as 50 degrees.
Freezing temperatures
September and October are a good time to close the pool because the weather is ideal. It's still warm to be outside, enjoying the sun, even if you hate to say goodbye to summer. But once those temperatures start dropping significantly, you're going to kick yourself for not closing the pool sooner.
First signs of it appear in small clusters on pool steps or lurking in corners. It's at this stage that you should start to attack it — green algae can grow quickly in 24 hours or less.
Lower chlorine levels can lead to faster algae growth. This is because low or inconsistent chlorine levels contribute to poor water sanitation. Poor water sanitation is a factor that can lead to algae growth.
You can get rid of algae quickly by vacuuming and brushing your pool, balancing your pool's water chemistry, and then shocking and filtering your pool water. Just be thorough as you clean your pool surfaces. If you leave behind even a small number of algae spores, it won't be long before they regrow and bloom again.
ADD POOL CLARIFIER
The change in your pool water colour means that you have successfully eliminated the algae and can now clean it out of your pool. If your water is still green, wait another 24 hours and redo the steps from Days 1 and 2. Now is the time to add Pool Clarifier and let it circulate for 12 hours.
Algae create a chlorine demand in the water for itself, consuming chlorine that should be working on other contaminants. As it expels carbon dioxide, the pH level of pool water can rise. Algae are kind of like weeds in your garden.
Much like the veggies in your garden, when the water is cold algae won't grow. Algae is not happy if the water is below 50 degrees. The winter kit chemicals dissipate after a few weeks, but they help keep your chemicals balanced and the pool clear until your water turns into a popsicle.
Under what conditions do algae grow best? Algae grow best when they receive 10 -15 hours of sunlight a day and the temperature stays between 60-80° F.
Green discoloration in a swimming pool is caused by the growth of algae, a type of green aquatic plant that floats on the surface of water. Algae usually flourishes in warm water but can still take over your pool in winter if given half a chance.
Grab a brush and some baking soda. Bicarbonate, the active ingredient in baking soda, is an effective spot treatment to help kill the algae and loosen it from the wall. Make sure you really get every last particle free; black algae has particularly long and stubborn roots which makes it a persistent strand.
Knowing how to lower pH in a pool keeps it comfortable for swimming. It protects your pool filters, pumps and liners from damage. Water with a high pH level reduces chlorine's effectiveness. This can lead to other problems like cloudy water and algae buildup.
If the amount of chlorine in the water is low, it could quickly cause algae growth in the pool.
Chlorine is still one of the most effective killers of algae so doing a super-chlorination of 10-20 ppm of chlorine can go a long way towards wiping out the algae. Liquid chlorine is an ideal shock for algae because it is fast acting and does not add cyanuric acid (CYA) or calcium to the water.
A great way to determine if algae is present in your pool is by identifying what the pH levels of your water are. If the levels are too high, it's likely that algae could begin to grow. For basic monitoring, you should consider the pH1000 sensor, which is designed to be used with pools.
Shock and Chlorinate Your Pool
Shocking kills any bacteria that might linger in your pool during the winter. We recommend shocking a few days before you close the pool. If that is not possible, make sure to shock the pool the night before you close it for winter.
When preparing your pool for a storm, leave it uncovered. Installing any kind of cover across the pool will not do much to protect against dust and contaminants because storms often bring strong winds and heavy rain that can cause the cover to lift off your pool.
Set your pool heater's thermostat to a temperature between 78°F and 82°F (26°C and 28°C) to keep the majority of swimmers comfortable. Maybe a little cooler if you're in an area with very hot summers, or a little warmer if you live in a milder climate.
Pool water turns green because of algae in the water. Algae can grow rapidly, particularly when it's warm like Summer, which is why it can surprise you overnight. This generally comes down to an imbalance or lack of chlorine in the water.