Thats so bizarre. I don't know what to say beside to slow down with adding new nems to your aquarium before you work this through. My guess is: something critically wrong with your aquarium or you just keep on getting dieing animals. I'd also advise to introduce em one at the time and observe how it goes.
Instead of buying em from LFS maybe you could collect your own anemones, that way you'll make sure you got healthy specimens.
I don't think your salinity is so much wrong if you keep Red sea species, Red sea is known to have much higher levels of dissolved salts (love the Sinai btw. and wishing to visit it soon again).. What's your water temperature? I know how hot summers are over there in Egypt and without good cooling unit you cant really run healthy aquarium, with stable temp. levels, I guess..
I'm no expert but I don't think your carpet would cause this to happen, folks on this board keeping em together with other nems, and all looks well..
