I have the skimmer running for about 16 months or so. I think the problem has occur awhile back when it stops working once in a while and I had to turn off the power and then back on again. So basically, it wouldn't skim the water all the way to the top and made noises that can be heard in the next room. I hope this help. The pump has a 3 years warranty so if it is over a year I would take the impeller out to inspect it. Other than that it is a good skimmer and the people from Coralvue are very good. They response to me in the morning after I emailed them and once I found out the problem they send out a new pump to me on the same day. Now, that's customer service.