I have a 15-high tank that has been used as a freshwater tank for over a year. The top of the tank is an Eclipse biofilter wheel setup. Before the tank was a freshwater tank, it was a brackish tank, housing spotted puffers (t. nigroviridis). When I moved a few years ago, all my puffers died before I realized that the water in my new home had an incredibly high pH. I was heartbroken over the loss of my 3 puffers, and converted the tank to fresh. I moved again recently, and moved my freshwater tetras that were in the 15-high to a 5-gallon tank at work where they seem to be very happy. I set up the 15-high tank as a freshwater setup in the new home, and have let it run for a few weeks until I could get a little more settled. I have a ton of Java Fern that I've had since the tank was brackish two years ago. The substrate is small rounded rocks, not the typical stuff sold at PetsMart but a much finer rock. I want to add a piece of driftwood as well, one with holes so that the Puffers can play in the holes when they're swimming. To prepare the tank for brackish fish, I put a small amount of aquarium salt in it last weekend to give it some salinity. Now, I've heard that you have to use marine salt for brackish fish, but I read online somewhere that for juvenile spotted puffers the salinity can be low and aquarium salt is good because it doesn't jack up the pH. I figure I'd just use aquarium salt for 6-8 months, and then slowly begin adding some marine salt while carefully monitoring pH. I have a few concerns. First, the tank had a MAJOR infestation of snails. I don't know if it's because of the added salt or what, but the snails seem to be disappearing. Should I do a water change (or 2 or 3) to try to siphon out what may be dead snails in my tank from the salinity? Has anyone else had experience converting a freshwater to a brackish in regards to the biofilter wheel and whatnot? I had three puffers that lived in the 15-high happily for over a year, until the move, but I think I will have it be a one-fish tank. What experience have others of you had with having more than 1 spotted puffer in a tank? Any advice would be great.