I've always boiled mine for 10/15 minutes before it goes in my tank (and made sure it is suitable for freshwater), also maybe worthwhile using an old toothbrush and scrubbing with some warm water, being careful to avoid any detergents or soap.
Cool yeah it's suitable for tropical made sure of that first. I'll give them a clean and boil away and then put them in I'll see what happens! Fingers crossed