Revese Osmosis water is filtered to remove any impurities. If you are not already using it I would be surprised if your anemone will survive. In addtion you will most likely see a lot of algae growth on your rocks. I couldn't keep any marine inverts alive until I switched to RO water. Actually RO/DI (de-ionized) water. Most folks on here will agree that it is a must in most situations in order to keep a reef tank, unless your water is amazingly pure. There are many sources online where you can buy a RO filter unit, you can probably get a decent one for under $200.