It can literally take less than 2-3 days for your pool to turn green if you been neglecting it, how and why does your pool turn green, and how to fix it?
First, let's discuss how and why your pool turn green after a while. If it's been a few days, the reason is most likely to be chlorine deficiency. Green pool water is often caused by the presence of algae in your pool. Algae blooms can appear when your pool has a low 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.
Now, what can you do about it? If your pool is green due to algae, you will need to Shock the pool. This will kill the algae and get rid of the green color. You will also need to run the filter for 24 hours to remove the dead algae.
There's another case scenario in which the green color is due to debris or leaves, in this case you will need to vacuum the pool, and also run the filter for 24 hours as well to remove all the debris from the water.
Once you have removed the algae or debris from the pool, you will need to run the filter for 12 hours to remove any residual algae or debris. You should also add fresh water to the pool to replace any water that has been lost.
Now, you're free to enjoy clear and healthy water on a hot sunny day.