S,
When adding DE you should remove the socks first.
The best way to do it is to put the dry DE in a five gallon bucket. Add water. You will be amazed at the amount of water you can add, it is as if the DE is not even in the bucket. Stir into a slurry and then, with the pump running, slowly pour the slurry into the skimmer basket.
Thanks,
Jim R.