Might be wrong butt looking at those rocks your system still seems pretty new. If it just goes a bit lighter than when you got it, it might be due to less nutrients in your system.
didnt have a alk tester so i was relying on the trident only had it a month but i was told it takes more than a month to be stable so i was dosing gonna do a water change to try and bring it down ive always had high alk but never had sps was always with lps softies easy stuff this set up is gonna be a sps dominant tank