The only time I ever see phosphate pads used are in marine aquariums and even then they are not a must have, carbon however is a different matter.
Oh and don't forget to make sure they are properly dried out to avoid them turning weird or something.
PS. Don't worry, I'm not really going to go around using wrong words deliberately, i would look a right muppet!
"Muppet"? Must be a UK thing?
Unless you mean... Kermit and Co.
It is a UK thing, Means uh... Retarded or something alike