I just converted my 40gal over to a brackish tank. It has two figure 8 puffers and a goby in it. Currently the level is at 1.005. At the LFS they had the salinity listed at 1.018-1.021. After all the research I have done this appears to be almost full marine (please forgive if this is incorrect, I am new at brackish). I have had them in the tank for three days at this level and they seem to be doing fine. Do I need to start doing water changes or something to increase the level to what they were living in? Just not sure what to do. Really like the puffers....also, how big do they really get. What is the best diet for them? In a 40 gal, is there room for anything else? Any help would be greatly appreciated. Thanks in advance.