Algaecide is the best way to prevent algae from growing in your unused pool. Generally, the colder the winter, the longer-lasting algaecide you'll want. Some winter algaecides last up to three months. You should pour in the algaecide on the last day you use the pool for the season and let the pump run for 24 hours.
When closing and winterizing your pool, it is important to remember to balance your pool water's chemistry prior to closing and don't forget the algaecide.
Algaecide should be added to your pool water on a weekly basis. Preventing algae is the key to fun in your pool. Algaecides act as a backup to your normal sanitization program and prevent algae from starting and growing in the pool. Algaecide should be added after every shock treatment.
You really only need one chemical (algaecide) to properly winterize a swimming pool. You need some other stuff to protect your pool from harsh winter conditions, but only one chemical to add when closing.
Algaecide should be used after each shock treatment, so it has a better chance to support your chlorine as it works its magic. Be sure to shock your pool first, then when the chlorine levels of your pool return to normal, add the correct amount of algaecide to several places around your pool while your pump is running.
One final note on algaecide: Contact algaecide is different from liquid algaecide. Many liquid algaecides don't work in cold water, and we don't recommend using them even in the warm months.
When your pool water turns from a lovely shade of blue to a sickly green, there's only one reason: pool algae. If it's a light shade of green, the algae has probably just started to take hold. But a deeper green means a bigger problem. Algae develops when the pool's sanitizer levels are too low.
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.
Add a dose of algaecide, bring your chlorine level high by shocking, and run the filter continuously until the problem clears. The next day you should vacuum up the dead algae and backwash your filter. Algae thrives in hot weather and in pools with low or no chlorine.
Liquid Algaecide is a strong algae depressant used for the prevention of algae growth and the maintenance of sparkling water in pools. Algae growth is the main cause of “off” colours in your swimming pool water. Prevention is important, regulated use of liquid algaecide will keep your water clear and shiny.
If you add algaecide, keep in mind that some algaecide contains copper, which can actually make a pool cloudy. If the cloudiness persists 24 hours after shocking, then it's possible that you used a poor-quality chlorine shock.
The presence of too much algaecide can lead to a foamy pool water. Small bubbles will begin to be produced as the water is pushed through the return jet and back into the pool. Do not confuse these bubbles and foam with another common problem, which is air in your pool lines.
We recommend an optional winter cover for inground pools because it makes winter maintenance easier. ... Never use chlorine tablets during the winter: you'll want to opt for Assault 73 Shock or Quick Shock granular chlorine once a month (1 pound per 10,000 gallons.)
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.
Should the green be due to pollen, there may be little to do in the way of minimizing the discoloration short of erecting a building around the pool. Fortunately, assuming there are no allergies to the pollen, it is safe to swim in a pool with that as the cause for green water.
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.
Don't Bother Unless You Absolutely Have To
Algae happens, but you usually don't need an algaecide to get rid of it. Keeping your water chemistry clean and well balanced will prevent growth in most cases, while superchlorination with pool shock can handle minor and common infestations.
Algae grows slower in cold weather...but it still works.
Some species of algae are adapted to survive in cold temperatures, such as the 39º F water under the ice. The growth of these winter algae mainly depends on how much light and nutrients are available to them.
Pools can immediately turn green after shocking when they have metals like copper or iron in the water. These metals oxidize when exposed to high levels of chlorine which makes the pool water turn green. Metals in the water are caused by some algaecides and using well water.
Registered algaecides include copper sulfate, copper chelates (ethanolamines, ethylene diamines, triethanolamines, triethanolamine + ethylene diamine, and copper citrate/gluconate), endothall (as the mono (N,N-dimethylalkylamine) salt), and formulations containing the active ingredient sodium carbonate peroxyhydrate.