ph is a little high, but none of your parameters have anything to do with these anemones surfacing. they are just common hitch hikers. they hitched a ride on that live rock you bought.
to control them they need to be killed. people kill them with various methods, some of which are mentioned above. i have heard of people injecting them with boiling water, vinegar, and lemon juice. there is also a product called "joes juice", that comes with the applicator (i believe a syringe) and detailed instructions.