Do I need to adjust my Specific Gravity?

[jassz]

Thank you for you replies. We use refractometers where I work, and check the zero (I think what you call calibrating) daily, as well as run two known controls. So I know they are accurate. I will take a sample in and check it.

So, if the SG is low, how might this affect the fish? The Stars and Stripes puffer seems very lethargic, and he was actually puffed this morning when I went down there. The dog might have scared him. He ate some food off a stick the second day or so, but I haven't seen him eat since. I also haven't seen the lion fish eat since the second day or so. Everyone else (2 triggers, another puffer and a wolf eel) are eating like pigs. I tested the water yesterday, and it was neg for ammonia, nitrate and nitrite, and the pH was 7.8 (which is what it has been since I got the tank). Is that a little low?

Thanks again.