Green water

[o2cool]

Good morning this is my first post. I was hoping you could help me with a couple of questions. We have a 55,000 gal. pool. When it turns Green with Algae; we treat it promptly put it take so long to clear. We have (2) two 36 gal.
Neptune-Benson sand filters; and use a 3 phase/5 hp StaRite pool pump. But it still take days to clear. Any help or advice you could give would be greatly appreciated. o2cool