It isn't worth the time and trouble to replace the small plastic filters at the sprinkler heads. You have to spend a lot of time with a fine toothbrush to get them clean and you have to make a second trip to the sprinkler and an "up and down" on our old, tired knees.
You can buy a supply of these filters at
Irrigation supplies and equipment from Dripdepot for $.20/each. If you have a serious problem with clogged filters, which many do, you should find the sprinkler at the end of the line, remove the head and flush the line. Most times, you'll be shocked at the "junk" that comes out of the line.
Drip Depot is a great source for everything you need for sprinklers. The on-line catalogue has more types of and variations of sprinkler than I knew existed. It beats making a trip to Ace, Home Depot, or Lowe's all of which have a limited selection of sprinkler heads.
Some posters remove and discard these filters and have no problems. That will not be true for most of us. It is a lot easier to replace these filters than to clean out a bunch of sprinkler heads.