I have green algae on stairs in shallow and deep end of pool, and on spots on the side. This is my brothers pool. He is too lazy to take care of it, so I have taken over the task. I have not shocked the pool yet, do you think that this is where I should start? Are there any brands of shock that work better than others? Another thing, he is only running his filter about 6 hours a day? Should I run this longer? Thank you for the help. John