I doubt the monsoon season has anything to do with it, unless it's dumping lots of stuff in your pool, or it's adding a lot more water and effectively diluting your chlorine--you need to be extra careful about keeping your Cl up during those rainy seasons.

There is no "normal" CYA level at a pool store--if you ask them the appropriate range, they'll tell you it's 20-200. That's a HUGE difference in Cl levels required. However, I can tell you that Cl of .5 isn't high enough, even with a low CYA level. I'm assuming your pool is vinyl liner--I would go ahead and shock the pool, using bleach, to 10 ppm while you're getting an accurate CYA reading. From there, we can adjust your Cl as necessary to get your pool cleared up. I wold also keep the filter running until it clears, and DONT put any more of the algaecide in it!

Janet