Gravel/rock sound in pipe

[Nulrich]

I am having an issue with air bubbles in my pump basket. When I turn my pump on it runs fine with almost no bubbles. After 30 seconds (sometimes a couple minutes) slot of small bubbles start to form and I hear a gravel/rock sound in the pipe coming out of the ground. The poly pipe underground is connected to a 45 elbow. I only have one pipe from my skimmer. I also hear bubbling in the filter.

What could cause the cavitation/rock/gravel sound in the pipe? I don't seem to be losing water so I'm not sure if there's a leak underground.

 

[pooldv]

That noise is called cavitation and it is usually caused by a clogged suction line. Been vacuuming or doing something to clog the pipe?

You can add your pool info to you signature so that we can help you better. More here, Pool School - Read This BEFORE You Post