Poor Marco. Ever try running it with nothing in it, no media and such? Mine got louder when I added filter floss and it had trouble moving the water though.
My Tank: 20 Gallon Freshwater High Tech Planted
My Plants: Dwarf Sagittaria, Riccia, Crypt Lutea, Rotala Macandra, Corkscrew Val, Blyxa Japonica, Ambulia, Anubias Nana, Flame Moss, Christmas Moss, Echinodorus Parviflorus.
My Fish: 1 German Gold Ram, 3 Praecox Rainbows, 1 Otocinclus Catfish, 1 Siamese Algae Eater, 1 Rummynose Tetra, 4 Cherry Barbs
My Inverts: Ramshorn Snails, Apple Snails.