Could be a variation of many things. First thing I noticed, the hobbyist is using a biological filtration method very similar to Zeovit or Prodibio, etc... He is manually adding nitrifying bacteria, a carbon source, and providing bioballs and ceramic rings to colonize the bacteria. This is your...
What are your phosphates at? If your running ULNS, what are you feeding the corals? Also, you have a very wild pH swing. Your swing is almost 6 points every night, that stress will kill off many corals. What are you dosing for Alk?