If you maintain proper chlorine levels, then phosphates will not cause an algae bloom. Basically, you can keep algae from growing in any number of ways:

1) Keep out all light. Algae needs at least some sun to grow (though not too much or the UV from sunlight ends up doing too much damage). Unless you are indoors and swim in the dark , this is not an option.

2) Take away at least one critical nutrient. This includes carbon from carbonates (can't take that away -- need it for pH buffer and calcium carbonate saturation), nitrogen from nitrates (hard to eliminate since it's in many bather wastes), phosphorous from phosphates. So really the only one you can realistically eliminate is phosphates (with a phosphate remover -- usually expensive), but it can always get blown in from farm (or your garden) fertilizer, etc.

3) Use an algaecide (PolyQuat 60) to prevent algae from growing and add it weekly.

4) Maintain proper disinfecting chlorine levels (enough chlorine for the pool's CYA level).

Option #4 is generally the easiest thing to do and is what is promoted on this pool forum. Since you have to have chlorine anyway for disinfection, you might as well just maintain its level to prevent algae growth and not have to add anything else.

Richard