Chugging vertex skimmer...?
 

My vertex in80 sounds like it's not sucking air as well as it should. It makes a chug chug chug sort of a sound... Almost like it's on and off on the suction. I've only had the skimmer for a few weeks now...and it was new. Any ideas? If I blow steadily into the air intake tube it sucks steadily and more foam seems to be produced.

Have you run the pump by itself to see how smoothly it's running? Check the pump intake and impeller when you have it out and ensure there isn't debris in there. Also check the air intake for any calcium buildup or dust. You'd be amazed at how little calcium in there can significantly affect air flow.

Thanks Tony... I'll check it out when I'm back in town.

take a cup of RO water, nuke it till it's hot and use a baster or if the airline is long enough let it suck it all up through the venturi.
if it's calcium that's caked on inside, u can dip the whole pump into a vinger solution for a while and let it dissolve any buildup that hot water won't do.

I do question if maybe some debris had got in there, but as I said, the skimmer is brand new, and only been running for 3-4 weeks. I'd be shocked and wondering what the hell is going in in my system if I have Ca caked on. I guess only time will tell though! Thanks guys.

Could just be dust or something like that. One of my skimmers is particularly prone to that, in that skimmer's case it's a combination of a higher air flow through a 1/4" line so the air velocity is higher than that on other skimmers and thus I have to give the intake a clean when I clean the rest of the skimmer about once a week.

check the muffler for restrictions. just got a bubble king that the muffler was assembled wrong and it was chugging as well.

Watch the water level in the sump and in the body of the skimmer. It might be changing in timing with the chugging.