Answer: If you are referring to white, chalky deposits on top of the soil, that is salt build-up from either salts in water (water in the West usually contains alot of salts naturally) or in fertilizer (synthetic fertilizers are made from mineral salts). The best way to deal with that problem is once a month leach the salts away, by putting plants under the faucet or hose and let water slowly and deeply run out the bottom of the pot. Water softeners that I am aware of are actually made from salts as well, so that doesn't help the situation. Some people don't water their plants with softened water because of it. If you have alot of salt build up, scrape it off the top. You might want to repot also, and then be sure to water deeply each time.
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