Steve came with a shell infested with algae. It was rooted so deep that I had to put him in salt water to kill them off. The shell was moss-eaten. It was devastating.
I added a thin layer of Siporax above the Subtrate Pro in my external canister.
And most of all, put the new PSB, Neo A.
It smells horrible like a sewer and stinks up the entire room, but hey, it means there are plenty of bacteria alive.
Hope it aids my tank cycling.