I noticed today that no bubbles were coming out of my air diffuser and my pond had frozen over. Pulled the air line off the aerator and it seems to be working fine. I’m assuming the air line is frozen can’t think of any other reason it’s not working. The air line is a 3/8ths weighted line. The diffuser is hanging about 1ft from the surface of the pond. Any ideas how to unclog it safely and not harm the fish?