Green or Dark Green Pool Water:
This means there's a medium amount of algae in your water and you'll need to triple shock your pool. Triple shocking requires 3 pounds for every 10,000 gallons of pool water.
Shock Your Pool with Chlorine to Kill Algae
This is the main event in clearing a green pool—killing the algae. Pool shock contains a high level of chlorine that will kill the algae and sanitize the pool. For the best results, use a shock that contains at least 70% available chlorine, and shock the pool twice.
You need to raise the level of your chlorine – shock the pool – and maintain that high level until all the algae is dead. This may take 3 to 4 days.
When there is not enough chlorine in your pool water, green algae—which can float freely or attach to the walls and floor of your pool—can grow. Thus, in many cases, the most efficient way to get rid of algae is by shocking your pool water with chlorine.
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.
You cannot overshock a swimming pool or add too much. Adding too much shock or overshocking your pool will kill off algae. The negative of adding too much shock is it will upset the chemical balance of your pool.
A good rule to remember is to use one bag of shock (1 gallon of liquid chlorine) per 10,000 gallons.
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.
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.
Neither will chlorination be effective with a diffuser and without a pump. The best thing to do is to apply liquid chlorine in the pool. Then, you have to circulate the pool manually with the use of a telescopic pole or paddle. This will ensure the chlorine disperse well.
A pool filter should be run for a minimum of 6 hours after shocking a swimming pool. This is to allow the filter to clean the water and give the shock enough time to fully mix with the pool water. Running the filter after shocking for 24 hours to 7 days is necessary if the pool has a large amount of algae.
It's not a good idea to use pool shock at the same time as clarifier. Some clarifiers are polymer based and the shock can act to break up the polymer causing the clarifier to be ineffective. It's best to shock your pool before and wait a day or two before adding clarifier.
Chlorine is a sanitizer, and (unless you use Baquacil products) is necessary for maintaining a clear and healthy pool. Shock is chlorine, in a high dose, meant to shock your pool and raise the chlorine level quickly.
After Shocking Your Pool
It is safe to swim once your chlorine levels are around 5 ppm or after 24 hours.
You should wait one hour per pound of shock product added, and then test the water to confirm the pH and chlorine are in the proper range before letting anyone enter the pool. As a reminder, you want your pH to be between 7.2 and 7.8ppm and your free available chlorine to be 1-4ppm for safe swimming.
It's pretty tough to over-shock your pool; shocking your pool two days in a row with the proper dosage for your pool volume shouldn't be a problem – and in fact, is sometimes even needed to rid your pool of algae and other contaminants.
How Often Should I Shock My Pool? Shocking your pool regularly will help to keep the water clean and free of contaminants. You should aim to shock your pool about once a week, with the additional shock after heavy use. Some tell-tale signs that your pool needs to be shocked are cloudy, foamy, green, or odourous water.
Backwash only as needed. Brush the pool vigorously, several times after shocking the pool. Do not use a solar blanket until chlorine and pH level are normal. If chlorine level drops to zero within 24 hours, Repeat the shock treatment.
Pools can immediately turn green after shocking when they have metals like copper in the water. These metals oxidise when exposed to high levels of chlorine which makes the pool water turn green. Adding a metal control product such as Zodiac Metal Remover will help to restore the pool water.
Green pool water is often caused by the presence of algae in your pool. Algae blooms can appear when your pool has a low Free Chlorine. Exposure to high heat, heavy rain or poor circulation, without the use of a preventative algaecide, also increase your risk of developing pool algae.
When shock chlorine oxidizes the copper, it turns green and that's what you're seeing in the pool. To get rid of it you'll need to raise the pool's calcium hardness by adding calcium chloride. The other culprit can be high levels of pollen.