adding more sand to established tank?

Hello all. This is my first post but I have been into saltwater for a long time. I just found this sight a couple weeks ago...I have a 220 gal that I recently converted from FOWLR to a reef tank. I removed all the sand from the tank before setting up the reef so I wouldn't leave behind yucky stuff. So the sand in there is only 3 month old but purchased live not dry. There are lots of copod's and such all in the tank as they were aplenty in the live rock. Which there is quite a bit of that as well....So my question. I didn't put in enough sand the first time and want to add 2-3 more bags but am nervous about the change in chemistry in the tank. Has anyone added (live) sand to an existing tank. There are only 2 fish in the tank but are lots of corals that I have been adding. Do you think I will throw everything off by adding one bag a week until full?