Hey there. To me artificial grass looks artificial. I don't care for it but a mixture if some of the artificial greenery that is available can look quite nice. Remember it will become faded as the summer goes on. If the top of the filter is open like a Skippy, you can use pots of live plants that will thrive.

Its hard without a picture of what you are talking about... but I was thinking why not build a shallow box out of wood or plastic and plant some shallow rooted annuals in the box. Then you can pull the box away when you need to clean the filter, and then put it back when finished with no harm done.

I had some artificial lily pads one year... after a week in the pond they looked like crap. I vowed never again to use anything artificial.

Some artificial (plastic) plants look remarkably good underwater. I stopped wasting money on living plants that were destroyed by Koi within hours and started buying greenery at Hobby Lobby when they have their half off sale. Certain pieces look enough like underwater plants that unless you are looking very closely you might not realize they are fake. I attach them to a coated wire shelf that I sink in the center of the pond. The eight inches under the shelf serves as a hiding place when the fish feel threatened, the foliage is soft yet sturdy enough to reduce spawning injuries, fry survive quite nicely in the dense foliage, algae grows on some of it that makes it look more natural and provides food for the growing fry and for winter snacks. They are non-toxic.The better quality pieces last two years before they start to break up. I can arrange the plants on the shelf to satisfy my artistic wishes. The spread of the foliage on a 12 inch by 20 inch shelf extends to 4 feet in all directions and can rise to the surface. Properly arranged, you can't see the shelf.

While it is true I don't have any blossoms like lilies, I don't have the frustration of seeing the plants destroyed and the mess to clean up. They require little maintenance. The most I have spent was $50 on two completed shelves.

Artificial grass looks real and is green in all seasons.