I don't know where you read that anemones are filter feeders. If it is a book, throw it away
Anemones need to be feed..and quite often. Feed them silversides..take a trip to the grocery store and get shrimp, mussles, scallops, squid, or any type of ocean white fish such as grouper, sole, sea bass. Don't get oily fish such as salmon, herring, or tuna. Feed your anemone at least 2-3 times a week. I feed mine every other day. They have grown and divided many times.
If you are not feeding an anemone, it is most likely starving to death. Also, don't rely on clownfish to feed it. They won't get enough to eat this way.
Here is a quote from part of a discussion with Dr. Ron Shimek:
All organisms are on an energy budget. Anemones can get income (nutrient energy) from a number of sources - direct feeding, indirect feeding (fish feces, drifting food, particulate material in the water (bacteria mostly)), some direct absorption of dissolved nutrients and zooxanthellae byproducts. Zoox byproducts are basically carbs only, so for growth the animal needs some sort of food.
All of the above sources have to sum to 100% of the needs for the organism to stay at status quo. Less, and it will shrink and my die. More and it grows, and may reproduce.
The fact that a lot of anemones die is reason enough to realize that most folks don't feed there systems enough. And... all the light in the world will not substitute for food if the animal doesn't have a nitrogen source for proteins.
HTH
[ November 05, 2001: Message edited by: Amphiprion ]