Ok, I admit it, I'm terrified of canister filters! I have 2 Rena filters, one the large XP3 and the other I think is an XP1. Or an XPL and an XPS. The bigger one has 3 trays and the smaller has 1. I think. I've been so scared to use them that I finally just put them and all the media-filled trays in my storage cupboard So...what tips can you give me for how to set one of these up? I'm scared!