as for the xenia I was going to put it in my 75 gallon because a few people told me that it would be a good way to tell if you water quality has changed. and I asked him if he had any zoo's or mushrooms left for my 30 long. I was looking for one or the other. I didn't know which one was left for sale.. as for the tang smart ***, I was helping a guy that I talk to in the connect message board. which I forward the link to him. so there you go mr.know it all.