Never tried them seemed overkill if you have a skimmer already. The dissolved particles go to the skimmer and sediment well you know where sediment goes.
It depends on what you want. The felt ones work much better, they catch a lot more. But because the nylon ones dont catch as much they last longer. And I came to this conclusion from using both. If you hold up the nylon ones you can even see through them partially which you can not with the felt