Question
There is a white layer on top of the soil in all my house plants. What is that,and how do i get rid of it?

Answer
Hi Laura,
  It is pretty common for the top layer of soil to get a layer of salt crystals (A byproduct of fertilizer) and/or Botrytis mold on it. I usually just scrape off the top 1 inch layer of soil and replace it with fresh soil.

To prevent it from coming back, reduce the amount of fertilizer and water.

As a general rule for watering plants, allow the top 1-2 inches of soil to dry between watering then water just enough for a small amount of water to drain out of the drainage holes in the bottom of the pot.

For fertilizing, I recommend using 1/3 of the amount called for in the directions on the package. Liquid fertilizers are best. Dilute 1 part liquid fertilizer to 2 parts distilled water.
If using a dry crystallized or powdered fertilizer, mix it with distilled water according to the directions on the package then dilute the mixed fertilizer as recommended.

You can also lightly spray the top of the soil with Lysol to help prevent the mold from coming back.

I hope this helps. If you have any questions or need additional information please don't hesitate to ask.
     Thanks
       Tracy