Hello,
1) How long is your tank cycle.
2) Dosing bacteria and everything uses live rocks/sand?
3) What’s your skimmer?
Have 9 tangs in my 5 feet tank and it's ok as my tank is cycled properly, if you add all at one shot (tangs are known to be poo machine = nitrate sure goes up, if your tank is not cycled properly and running a under skim skimmer, i would suggest to sell most of it and leave 1-2 tangs and adding it slowly (though it's good to add alot at one time to minimize aggression)