How to determine if close to an algae problem?

I was just wondering. I have had my pool one year and luckily no algae yet. However, I am not sure I would know if I was close other than looking at the water. What readings give you clues. I do not think I am near an algae bloom but I will post my numbers anyway.

20,000 gallons
SWG
Pebble Tec

FC 2.4
TC 2.4
CC 0.0
Alk 122
pH 7.8
Calcium Hardness 201
CYA 49
Saturation Index .01
Phosphates are around 500

I think I need more chlorine due to my CYA level and I need to lower the Phosphates. But what other factors should clue me in. Please let me know as I am still trying to figure this out.

Thanks as always,
Mike

You are right that you need to raise your cl level. Don't worry about the phosphates. If you start using a lot of chlorine - more than usual - and you have a CC reading, that usually means you are fighting something in your water. Or, sometimes your water will start to look cloudy.

Thank you very much.