When you began adding in some of your corals did you have to add anything into the tank to keep them alive or are they just completely off light? Do you have to give any of yours supplements?
You don't have to add anything for soft corals and LPS because they live off light for the most part, but they still use a very small amount of trace elements that are replenished with water changes.
I have found that a Sally Lightfoot crab will do a number on thinning out the fireworm population in a tank. not to mention they are cool looking as well!