Realistically,MOST sps should not be added until you get to about 6-8 months,or you see purple coralline algae growing. Its a very good indication of stability and maturity in a system.
I personally have added way earlier,and had probelms and then had great success. You can't always go off of people success stories,well because the ending to every book ever written is never the same.
There could be metals leeching into the systems,stray voltage,instabilities. If you alk is really 13,that could be a problem. If other parameters are not in line with it,it will cause problems like you are seeing.
Every day new things are learned about how parameters are connected and if one goes up or down it effects 1-2 params with it. So its important to pay close attention.
I always used my more finicky sps as an indicator if something was off. If things browned,I knew the check this,if things stn'd or rtn'd I knew to check that so on and all that.
Having a reef tank is like having a happy and healthy marriage. KEEP IT HAPPY TO KEEP IT HEALTHY !!!