Favites help-newbie

[lilfish717]

OK so this is involving both lps and sps do I'm going to post on both subs. I am new to this hobby. My first and currently only 2 corals are pavona and a favite. I've had them about a month. I also have 4 hermits a clown and a cleaner wrasse. Both corals were fine in the beginning. About 4 nights later the favite had his tentacles out and I hand fed him brine shrimp EVERY night. I noticed he was growing and everything. The pavona never ever had his tentacles out or everything about 1-1/2 weeks ago he started browning out. And got worse by the day. So after about 4 days of that I turned the lights up. Then I had a diatoms bloom at the same time just coming on. After the lights going up I ended up calling it S night early and didn't get to feed the favites. The next night I went to feed him and his tentacles weren't out. They have only been out once and only a little out about 4 or so days ago. Threes days after the lights going up the pavona appeared to be covering the frag plug a little more as if it grown a little my girlfriend agreed. At this point it didn't lose much color. Then a few days later it was back to the same old losing color and going all brown. The favites appears the same and to have nothing wrong. Today the pavona appears to have a few spots back as shown in the pictures I'm about to post. What do you guys suggest/tips? My params are:
Ammonia-0
Nitrite-0

Nitrate- Api test strips read 40 and reef master is reading 60. It read 40 last night after water change. I know my tap contains nitrates but I let it sit out for 3 days with 1200 gph powerhead. And it's usually 20 at most I don't have access to Rodi water. :/

KH-off the charts API test kit measures up to 214.8 ppm and I doubled that and still no results so I stopped there which I assume would be around 429.6 ppm and my guess is it's around 500-600 ppm. I don't know much about how high KH can effect and aquarium.

Calcium-500 ppm
Ph-8
Phosphate-0 ppm.
Temp-between 78-80 all day every day

All my results seem pretty good to me expect the nitrates and the KH. I don't know what the problem can be. I really appreciate anyone that took the time to read the long thread and reply to try and help me and I apologize for the long post. Thanks

 

[NY_Caveman]

Tap water may also have metals in it as well as Nitrates and high Phosphate. I would try to get ahold of your yearly water report. You can usually find that online. Have you tested the TDS of the water?

You might consider using distilled water. I used it for years with no issues when I lived in Manhattan in a tiny studio apartment. It really all starts with high water quality. Hard to diagnose specific issues with the unknowns coming from the tap. Perhaps an ICP test would be useful as a baseline to see if any metals are elevated.