If your pump is suspiciously noisy, especially just out of the box, you should contact the manufacturer. These items are very small and can often have mechanical issues. Once you have a properly functioning pump, be sure to place it correctly on a solid surface a few inches away from your tank. If you do not have a check valve, be sure to place your air pump above your tank’s water surface to prevent backflushing down the line in the event of a power outage. Most air pumps come with rubber feet to limit vibrations. Make sure no other filter components are touching your vibrating air pump. If your air pump is still too loud, try placing it on a block of foam or an extra filter pad. Try to avoid building a foam box for your filter, since this can cause your unit to overheat. If your filter is still too loud, despite modifications, you might want to get a new one.