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.
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 (calcium hypochlorite).
The free chlorine levels might be low.
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 fastest way to clean a green pool is by using pool chemicals and your pool filter. This process usually takes around 4-5 days but you will start noticing a major improvement after 24 hours.
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.
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.
Baking Soda and Green, Blue, or Yellow Algae
You'll need to use an algaecide to kill the algae and superchlorinate your pool to clear the water. After this treatment, test your pH and alkalinity and add baking soda to raise alkalinity to at least 100 ppm and pH to between 7.2 and 7.8.
Should I drain my pool to get rid of algae? Yes, you can because it saves time and money, but only if you do it properly. Use the main drain in your pool and drain water through the filter pump. Or rent or borrow the pump, place the hose down the street or storm drain, and drain.
Light Green or Teal Pool Water:
To double shock, you will need to add 2 pounds for every 10,000 gallons of water. For instance, if you pool is 20,000 gallons, you will add 4 pounds of shock.
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.
If there's not enough chlorine, your pool can turn green. pH Value too high. - pH is a measure of how acidic or basic the water is. A number of different factors can contribute to a high pH level in a swimming pool.
In theory, if you have a cloudy swimming pool, you can add chlorine to “shock it” and clear things up. Chlorine will get the job done. But, the amounts may vary and you may have to really pound the pool with chlorine to get the water totally clear.
When to Replace the Pool Water
You should replace pool water every five to seven years. As much as possible, you should drain and refill your pool during mild weather. It's to avoid pool damage caused by direct sunlight and heat. Moreover, a pool maintenance company can recommend the ideal time to drain your pool.
Poor water quality, due to an overabundance of Total Dissolved Solids or high levels of Cyanuric Acid, is the most common reason for needing to drain a pool. Even with proper and regular pool maintenance, it's often necessary to drain your pool — completely or partially — every 3-5 years.
Draining a pool can take up to 14 hours, depending on the size, so be sure to drain it on a day when you have sufficient free time. You need to be home to check on the pool, the hoses, and the pump frequently. Do not let the pump run dry or it can become damaged.
Clorox itself recommends using between 100 and 200 ounces of regular-strength bleach per 10,000 gallons of pool water -- one gallon is 128 ounces, and many bottles of bleach are available in one-gallon or half-gallon sizes. Pool professionals tend to recommend more conservative amounts of bleach.
It is important to know what exactly bleach is before you put it in your pool. Household bleach, Clorox and liquid chlorine can all be used to sanitize a pool. They are all types of chlorine. Household bleaches such as Clorox usually contain about 5-6% available chlorine, about half that of pool liquid chlorine.
Just like you run vinegar through your coffee pot to get rid of calcium buildup, white vinegar can wipe away this eyesore in your pool. Mix a 50/50 solution of vinegar and water, dip a sponge or soft cloth into it, and scrub that residue away.
Baking soda can work wonders in a pool. Baking soda can: Help to clear cloudy water and restore the sparkle. Spot-treat algae.
I think the answer to your question is about 3-6 days. The problem is that the chlorine that you need to keep the bacteria in check is used up more quickly as the temperature rises, the activity increases, and as sweat and other body stuff is put into the pool.
pH will also have an effect. If the pH is high, your chlorine is slow to react, and algae can begin to form, making the pool appear green or cloudy. If the pH is low, the chlorine will be “hyperactive”, reacting quickly, and dissipating out of the pool too rapidly, causing a low chlorine residual.
If your pool is green but chlorine is high, it's possible that you aren't running the pool's filter often enough or for long enough to filter out algae and bacteria. In spring and summer, when it's warm outside, pools should be filtered for eight hours a day, regardless of whether the pool is in active use.