As I previously mentioned in my list of pool care essentials, having a thermometer to track your pool temperature is important because algae loves to grow in hotter temperatures––generally 85 degrees or above.
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.
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.
A living plant organism, algae can appear suddenly. It can clog filters, reduce water circulation and lower the effectiveness of your pool chemicals. Factors like low chlorine levels, heavy rains and high heat can cause algae to flourish and make matters worse.
1. 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.
Warmer temperatures prevent water from mixing, allowing algae to grow thicker and faster. Warmer water is easier for small organisms to move through and allows algae to float to the surface faster. Algal blooms absorb sunlight, making water even warmer and promoting more blooms.
Algae will be in any pool without chlorine in it. With cold water, it just does not multiply quickly. But once your water gets much above 50F, it will start. Above 60F, it will bloom.
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.
Algae can be very slippery, causing swimmers to fall resulting in bumps, bruises, cuts and even broken bones. Don't try to swim in a pool that's full of algae. Besides causing injuries, an algae infested pool creates a higher risk of drowning for those who are not expert swimmers or those who fall unconscious.
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.
Cover Your Pool
Not only is a pool cover a barrier to algae entering the pool, it's also a barrier to leaves, bugs, bacteria, and dirt from entering the pool, decomposing, and providing the nourishment that helps algae to thrive.
When the levels are properly balanced, chlorine will keep the algae at bay, but the water will slowly begin to turn green as the algae take over if there's not enough. But be careful—adding too much chlorine in pool water can cause those metals to oxidize and turn the pool a different shade of green.
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.
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.
Green Algae
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.
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.
1. Shock the pool with chlorine every day until all the green is gone (possibly 3 to 4 days). 2. Run the filter 24 hours a day and backwash every day until the green and then cloudiness is gone (usually up to 7 days, sometimes as long as 2 weeks depending on the filter).
Best swimming pool algaecide for all pools
For an all-purpose swimming pool algaecide, we recommend Kem-Tek 60% Algaecide Concentrate. This pool and spa algaecide contains 60% of its active ingredient, polyquaternium WSCP. It's effective at removing most types of algae and preventing them from returning.
A nylon or rubber brush is the correct choice for scrubbing the sides of a soft-sided above-ground pool. A large pool brush makes quick work of the job, but you may need a smaller brush to clean corners. Once the particles have been removed from the sides of the pool, turn your filter back on and agitate the water.
The use of baking soda in pools can spot treat algae
No one ever wants to see algae build up in their swimming pool. It can turn any backyard pool murky green or cause unsightly black spots on the walls and floor of any swimming pool.
If you suspect swimming pool algae is making your pool water green or cloudy, check the water's alkalinity and pH balance. This is the most common cause of green pool water. Unfortunately, algae can become resistant to chlorine and sanitation because of the water's pH and alkalinity.
If you close your pool too soon, the winter protection chemicals you've added will often not last until spring. The reason is that your pool chemicals are consumed much faster in hotter temperatures versus in cooler temperatures. This can, in turn, cause algae blooms and staining in your pool.