I'd step it up a little more in your monitoring. Time to invest into a decent test kit and track whats occuring from week to week. alk-cal-mag, nitrates/phosphates at the bare minimum. You might be consuming more than you think and the water change is increasing alk far more than they are accustomed too. In adition you might want to start considering dosing if your consumption shows such. Get a baseline for where you are and then 3 days later test to see what you're consuming as far as alk/cal/mag is concerned. Remember to test at the same time period as your alk will be much lower in the afternoon prior to the photoperiod.
It sounds like a lot and seems intimidating at first but once you get a handle on it you'll be fine. It's cool to gain insight as to what your tank is doing and your corals will thank you for the added stability by blossoming.
It sounds like a lot and seems intimidating at first but once you get a handle on it you'll be fine. It's cool to gain insight as to what your tank is doing and your corals will thank you for the added stability by blossoming.