Why is my reservoir so loud?

[Skiguy411]

I recently finished putting together my water cooling set up, but the water in the reservoir is so loud. Every 2 seconds it makes this gulp sound that gets pretty annoying. What is the best way to quiet it down? How do I get the air that still in it out? I cant just add more liquid because it will overflow.

I am using this pump and reservoir.

 

[Cheesetogo]

Try slanting the res at different angles to see if you can get more water into it.