Is it ok to add live rock to a overstocked FO tank?

[lawdawg18]

I'm not sure if this is the right forum. I recently purchased a setup fully running 55gal saltwater fish only tank with fish. I drove 3 hours loaded up the fish, tank, equipment, and every drop of water. Drove 3 hours home, and set it up. Fish so far have been doing great for 3 weeks now. My questions are this. Would it be ok introduce some live rock to the tank? How does live rock affect the bio load? I feel that the tank is very over stocked and do not want to mess anything up. Would it be ok,safe, good idea, bad idea to add snails, crabs, or such critters?
I'm going to try to list what fish are in the tank, yellow tang, a purple with yellow tail fish that looks just like the yellow tang, a whitish grey fish that looks like the yellow tang, a chromis??, a adult emperor angel, a maroon clown, a smaller maroonish purple fish, and a sea urchant of sometype.
The tank has a undergravel filter, a canister under the tank filter, and a protein skimmer

 

[Edmonton Eskimo]

If you wish to introduce live rock into a tank with inhabitants you must first make sure it is cured. You can put it in a plastic bucket with some saltwater,heater and some kind of aeration until the ammonia spikes and goes down. If you can take some water from your tank and maybe half and half it with some fresh saltwater that would be good. Of course if it is already cured you will be ok. Be careful though because shipment or exposure to air for longer periods can cause some die off so it would be best to cure it first especially if your bioload is already maxed. HTH

 

[fishfreek]

Cured rock will filter the tank so it does not add to the bioload at all. If your going to add liverock to an established system please make sure its cured first. TO verify its cured put the rock in a temp holding vessle with saltwater and a powerhead and heater. After 24 hours check for ammonia and nitrite. If either exist then the rocks not cured. If neither test positive then you can safely add it to your tank.