Some additional skimmer information -
First off, and this applies to all equipment purchases, always buy top quality. This does not mean most expensive. Yes, this can mean that it will cost a lot more initially, but it will last and not have problems.
Skimmer manufacturers are very "optimistic" about the size of the tank you can use it on. Typically you want a skimmer rated for a tank that is 2 to 3 times the size you have. Since we are talking about a 30 to 35 gal tank, the skimmer should be rated for about a 70 to 110 gal tank.
Do your research before you buy. There are a lot of junk skimmers out there, and you don't want to get one of them. Read the reviews on them and ask questions.