Algae????

[aylad]

You need to shock the pool and hold it at shock level until the algae is dead, and until you can go from sundown one night to just before sunup the next morning without losing more than 1 ppm of chlorine. This is going to require a test kit that can accurately and reliably check chlorine, and is also going to require that you know your CYA level, since what level of chlorine you need to achieve is determined by your CYA level. (See the "best guess chlorine chart" linked in my sig for a more detailed explanation and the chart). Vac'ing the algae out will take out the visible stuff for the day, but is not killing off or removing all the algae. You will be fighting this battle until you kill it off, which will happen with a maintained shocking of the pool.