Hello to all. On saturday i'm going to get my new tank(160x50x50) I still don't decide about the sustrate. I have loaches now in a 180lt tank with fine gravel. 3 yo-yo, 3 clowns, 3 kubs(3 to 6 cm.) The yo-yos burrows all day. In other tank, 160x30x60, i have river-sand. In this tank, I've had proble...