ph shouldnt have anyhting to do with it as most fish can adapt if you accliamte them to it, also with your stocking your ammonia would rise super fast, and plecos for one are giant poop machines so that may be a reason why.
So now my best advice is do multipe PWC's a day too keep the ammonia low and i would advise against getting any fish untill you are cycled.
So now my best advice is do multipe PWC's a day too keep the ammonia low and i would advise against getting any fish untill you are cycled.