Yes my tank is only 6mths old. I do test for PH 8 to 8.2, Nitrite is usually 0, Amonia .25, Nitrate was 5, phosphate I just tested yesterday and it was at 4 and calcium was really high more than 500 and DKH was at 15.Sweet little setup.
It appears that your rock is from an established tank as I see the presence of Coraline. But your sand is pure. This is a very young tank.
It may very well be that you have added corals too soon.
Again, do you test for anything?