Ongoing struggle with algea

[ltorres]

we are dealing with a pool cleaning company that has not helped much. we are at the point of doing the maintenance ourself. Pool guy said something about getting a "floater' fixed. I don't know what that is, but the water turns green every two weeks and seems to have really poor circulation We shock it about every two weeks because it won't stay clean. Help

[chem geek]

I suspect you are using a floating chlorinator where you add Trichlor pucks/tabs as your source of chlorine. These will not only add chlorine that increases the Free Chlorine (FC) level that then gets used up by sunlight and fighting algae growth, but it also increases the Cyanuric Acid (CYA) level and that doesn't get used up. So over time, the CYA level rises and this requires proportionately higher FC levels and since that doesn't happen, the FC/CYA ratio drops and algae starts to grow. You can learn more about this at the Pool School.