How do you get alge out salt systems pools?

Algae is algae. It grows in all swimming pool water - indoor, outdoor and it does not matter what type of filter or how the pool water is chlorinated or brominated. All pools have salt in the water since liquid bleach is made from salt and calcium hypochlorite contains salt. Therefore all pools have salt. Just as all pools have algae.

Algae is a living plant that takes in nutrients.

Therefore in order to control algae something that prevents it from taking in nutrients will control its growth. The simplest way is to use a clarifier on a weekly basis in a indoor or outdoor residential pool or daily on a public swimming pool.

Swimming pool chemicals are a buyer beware market. Purchase a brand from a professional pool store or supplier if possible. Even then you do not know if the chemical purchased will do what the directions say it will.

Use an algaecide and a water clarifier weekly maintain the free chlorine around 1 ppm (not over 1 ppm or toxic chlorine by products will be formed and never shock dose or add a lot of chlorine since toxic chlorine by products will be formed.

Use a quality algaecide and superior water clarifier