I'm not sure this is something that goes with freshwater. I got a 72 gallon bow tank (craigslist find) & this came with it. I'm not setting the tank up right now as the new construction is not completed
Can anyone tell me what it is? and what do you do with it? I'm sorry if I sound ignorant, but I've only had smaller tanks (30 gallon and under) which did not have this type of equipment. Any information would be greatly appreciated. Thanks!

