The condense is part of the design. To be more precise, it actually enables the work to be self-sufficient. It works a little as rain does in nature, and will therefore differ in intensity. Sometimes you'll see more condense than other times. Ideally the humidity in the ecosystem should be above 40%. The moss, which forms the basis of the little world, works best with this percentage. The moss is preferably dark green. A guideline to ensure the biotope is moist, is to water it every 6 months with about 500 ml of decalcified water. Descaling can be done simply by boiling water without a lid. Of course you'll need to cool it properly. The easiest way to water it is by using a spray bottle. That way you can also clean the glass. Another way to clean the inside of the glass is with a bottle brush.