Awhile ago I reasoned that my pressure gauge didn’t work. When on or off it reads zero. Last night our pool had accidentally got drained a little bit below the skimmer so our pool pump most likely trapped air inside of it. Since the pressure gauge reads zero it of course isn’t telling me if our pool pump pressure is too high or too low. I read earlier that if your filter traps in too much air it can explode. I’m worried that when I am close to my sand filter it might explode due to the fact that there might be air in it. Do sand filters explode that easily or is it only when I take off the lid? Also what are the different ways I can get my pressure gauge to work again?