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.
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.
The chlorine in your pool acts the same way. Keep in mind, organic materials like algae, leaves, sunscreen, lotions, pee, poop, and etc., consume chlorine. As chlorine does its job, it is depleted in the process.
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.
Use chlorine as your go-to algae killer.
"Shocking" the pool with a large dose of chlorine is the most effective way to kill the existing algae and bring your pool back to sanitary conditions. This usually works within 1–3 days, but can take up to a week if pool conditions are poor.
The last thing you want to do is vacuum algae manually, which will contaminate your filter. Your pool will not clear up. In fact, the chances of your problem getting worse are very high. You'll also need to vacuum to waste when there is a large amount of debris or leaves in the pool, usually at opening.
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.
This is perhaps the simplest, long-term solution to keeping water clean and clear. Floating plants, such as lilies and lotus, provide shade and reduce direct sunlight in the pond to control the growth of algae. Add submerged plants that release oxygen to the water, such as anacharis, hornwort and parrot's feather.
If you test your pool water and can't get a chlorine level reading at all it may be due to a very high chlorine demand. A high chlorine demand is the inability to keep an adequate level of chlorine in the pool water even though the water appears to be balanced and properly maintained.
Chlorine lock can occur when there is too much cyanuric acid (also referred to as conditioner or stabilizer) in the water. This occurs when too much stabilizer is added to the water or when the swimming pool isn't being partially drained and refilled periodically. Chlorine lock can also occur if the pH is unbalanced.
Your pH levels affect your chlorine levels and the ability for the chlorine to do its work properly. If your water's pH is too high, it hinders the chlorine's ability to efficiently clean the pool. A water pH level that is too low causes the chlorine to dissipate more quickly.
Algae growing over larger sections of the pool, or suspended in the water will require a strong dose of chlorine pool shock, or granular chlorine, to kill the algae.
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.
Getting Rid of Algae with Chlorine Shock
Chlorine is a very effective sanitizer for water. When you maintain a swimming pool with 3ppm (parts per million) of chlorine, it will inhibit algae from growing.
While plankton algae blooms occur in response to warm and sunny conditions in the summer, the algae growth is supported by high levels of nutrients in the water (most often phosphorus and nitrogen) that may come from fertilizers, manures, septic systems, urban runoff or animal waste entering the pond.
Add barley straw to the pond to slowly kill the algae.
As it rots, barley straw will slowly release small amounts of hydrogen peroxide that will kill any algae growing in your pond. Buy a small bale of barley straw and throw it into your pond when you first notice algae growing in your pond.
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.
The dead algae is likely too fine to be vacuumed through your sand filter, therefore owners of sand filters must vacuum on the waste setting. Cartridge filter owners can vacuum up the dead algae but need to clean the filters thoroughly after doing so.
Use A Pool Vacuum
The most effective tool to get rid of dead algae is a pool vacuum, and there are two ways you can remove algae using a vacuum. The first method is the better (and easier) of the two, and can only be done if you have a multiport system, using either a suction-side or pressure-side vacuum.
If you have a sand filter and are vacuuming to waste, set filter to “waste” option. ... This option allows you to vacuum the algae up and send it out through the backwash line, avoiding getting algae into your filter sand. However, you will need to vacuum quickly, as water will be exiting your pool quickly.
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.