So I was bored yesterday and pulled off the pool cover. I knew there would be a few leaves and their were. What I didn't expect was yellow mustard algae on the pool walls and floor. I've kept up with testing the water and adding chemicals and running the pump for 4 hrs each day over the winter to keep it to where it should be. No big deal, just added some bleach and started brushing. Ran the pump and filtered the water over-nite and brushed a bit more today. Its been about 30 hrs now and the pool water is clear and I can see the main drain cover holes in the deep end which is 8 feet deep. I know the chlorine levels are high so I'm going to wait a couple of days and take a fresh set of readings and see what needs to be added or adjusted. Just don't quite understand why I got the algae when the test readings were all right where they should be. Any thoughts as to why??