Are there any clarifiers i can add to the secondary fermenter? I forgot to add my irish moss during the boil.
Depending on the style of beer you're brewing you might not need to add fining agents.
Kettle finings like Irish moss are used to help the "hot break" - proteins and fatty acids - formed during wort boil drop out of solution. If left in the beer, those proteins can cause flavor instability down the line and might cause the yeast to produce certain minor off-flavors during fermentation.
If you're producing an ale which is designed to be consumed young and you don't mind a bit of protein "chewiness" or haze in your beer, then don't bother adding finings in secondary. Chances are, most of the hot break will drop out at the end of primary fermentation anyway. The chances of screwing things up with finings probably are greater than the problems with hot break in your beer.
If it really matters, the simplest way is to use finings such as Polyclar, isinglass or brewers gelatin. Buy the appropriate stuff at your friendly local HB store and follow the directions on the package. Let the finings work for a couple of weeks, then carefully rack the beer again so that you pick up as little trub as possible.
If it really matters, and money is no object, you can do what the pros do: chill your beer to 32-35 degrees for a while, then run your beer through a filter.