The gurgling noise means you have air in the tank. If the sound goes away overnight, it could be air from starting up the pump. But if it continues, it generally means a small suction side leak, letting air enter your piping.

Another way to check is to use the air relieve screw -- that's the part that's leaking -- by opening it a bit, letting the air bleed off, and then closing it. (Don't unscrew it too far; it will come out and shoot off somewhere, most likely in the leaves where you'll never find it. ;-)

By the way, your pics are below.