I'm no expert, but I agree - hit 'restart' on this system's management. Weekly 10% water changes and no dosing until your system shows you (such as by testing too low in calcium for a while) that it actually needs it. Don't bother testing pH because when everything else is in line - alk, mag, cal, salinity - your pH will hold right where it wants to be. When you do start dosing, start SLOWLY and watch the results over a period of months. Don't just dump in the "recommended amount." From what I'm looking at, your tank is not stocked enough with corals to need calcium, magnesium or trace supplements right now. I personally would use amino acids, but the recommended dosage (I believe) is really based on a full tank, so I'd reduce it dramatically from the recommended amount-per-gallon for now.
Always get the exact numbers when testing, especially when having someone else do it. "Fine" is not good enough. You need to know the exact values. Even within "good" values, quick swings can cause issues, and just being within the range is not optimal, really. You have to find your tank's "sweet spot." GO SLOW. Corals will take a while to acclimate to any changes you make.
You say you used the same light on both tanks? You may have too little light; LEDs are very directionally linear light, so a fixture sized for a 56 would not be able to light an upgrade of that size adequately. Also, if you changed the height of the corals when you moved them, they may not have been able to acclimate to the new intensity. It also occurs to me that the new corals you got may not have been acclimated to LEDs. This is an important step; start new corals on the sand bed and sloooowly move them up as they adjust to the new light type. This is true when replacing fixtures and bulbs, as well; you will need to provide some shade (which is slowly removed over time) whenever you add intensity or change lighting type.