How much Can i cover the filterpump?
It makes alot of noise and i Want to cover the noise in put does it need "fresh" air or Can i completly seal it with a styrofoam box?
Yes and no. Your pump needs airflow, so it would need to be something that allowed some flow. Google pump cover and you'll see there are a huge variety of implementations - everything from pump buildings to "boxes" with side vents.
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