"Heavy rain dilutes pool chemicals, especially salt and chlorine, which causes the pool to turn green. This means the water is not sanitised or healthy, so it's vital to address this.
Rainwater itself does not cause algae, but it can provide the right environment for algae. Rain will bring phosphates, nitrates and other organic contaminants into the pool. As we discussed earlier, rain also reduces chlorine levels.
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.
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 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.
The only thing that kills algae is CHLORINE (or your sanitizing product, or one of the copper-based algaecides on the market). 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. RUN THE FILTER 24 HOURS A DAY.
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.
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.
ADD POOL CLARIFIER
The change in your pool water colour means that you have successfully eliminated the algae and can now clean it out of your pool. If your water is still green, wait another 24 hours and redo the steps from Days 1 and 2.
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.
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.
Keep your pump and filter running. Give the shock a good 12 to 24 hours to work it's magic. If the algae hasn't cleared up after 24-48 hours, clean and brush the pool and add another shock treatment.
Set up your waste line and vacuum the pool to waste getting the algae and debris out of the pool. Don't let the water level get too low during this process, if it gets more than 6 inches below the tile, stop. Turn the system off and refill the pool and repeat until the whole pool is vacuumed.
Bleach, like any other kind of pool treatment, is best used in specific concentrations -- that is, you'll want to be able to detect a certain amount of chlorine in your pool water. Too little, and you won't effectively sanitize your pool water and surfaces. Too much, and your pool water might become too harsh to use.
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. Household bleaches often have unwanted fragrances and colors.
The solution to maintaining a clear pool is to use readily available liquid bleach as your chlorine source. Chlorine bleach, as discussed above, is not bound to a stabilizer, so when you add chlorine bleach to the pool, it will go right to work killing microbes and sanitizing.
So while a solar cover won't actually 'turn your pool green', it will warm your water by up to 8 degrees, so if the other conditions are right, adding a solar cover can easily accelerate algae growth, very rapidly. You need to get the water balance in your pool right before putting the cover back on.
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.
Overall, the lessons learned today is you should run your pool pump an average 8 hours a day to properly circulate and clean your water. The pump should push your entire pool in gallons in this 8 hour period of time. Residential pool water only needs to be turned over once daily to have proper filtration.
Covering a heated swimming pool at night will reduce heat loss. That means warmer water, which is what anyone who has ever gone swimming in a chilly pool can tell you is very important.