I use a noseclip, because even a small amount of chlorine up my nose really irritates the lining. I use a Speedo one - like a small hooped piece of wire reminiscent of teeth braces, with flesh coloured rubber grips at either end.
As long I position it properly, by having the exposed wire going over the top, and the bottom of the rubber grips facing out the way, it stops everything (even air) getting into my nose. I've only ever used that particular kind, and find it great.
From memory it cost about £3.