What kind of corals did you put in the tank specifically? From your water parameters the only things that really concern me are your ammonia reading and your PH being 8.0. The PH not so much but the ammonia is a biggie.
The lighting you have on your tank (a 155g) is going to be more for a FOWLR
tank and not a reef. I'm not sure if low light corals would do well with that little light. You might be ok with some mushrooms or a low light leather.
I'm really interested in what corals you put in the tank and how quickly they died.