As long as you do not overload your system then the water changes will do the job. however, with a 55 you would be maxed out without a skimmer with a couple clowns and an anemone, some live rock, and substrait. a skimmer gives you more forgiveness and helps keep the system oxygenated and removes the protiens/waste in the water. as others have stated you will remove some of the good but it will be very minor with the protein skimmers used on home tanks. water changes will replenish all that is lost. protein skimming is recommended. oh and by the way some corals slough/wax off mucus, skin, chemicals, etc. the protein skimmer will remove most of that protecting the rest of the animals. good luck. pick one person you trust and stick with their formula. there are many opinions out here and no single one is the right one. there are many ways to get there but each process/formula has its pros and cons. good luck.