If your pool has gone green all of a sudden, or if you have just arrived back from a break away and you noticed your pool is turning green don't panic. Algae is a very common problem in pools. It can occur if your pump is broken, your filter is clogged or your chlorinator ran empty. Once algae sets in it will continually grow until all of it is eliminated. You need to nuke it with chlorine (free chlorine) until ALL of it is gone.