No metal in the tank or near it that could interfere. I have copper in the utility room cabinet for a hospital tank but have not used/opened it in over a year. Measured the pH last night so was not in the morning.

75 gal RR oceanic, 30 gal sump with refug (need to restock the macro), two 175w 14K MH, two 65 W PC actinic, and two 65W PC 10k. Use Red Sea salt (white bucket with orange lid), Remora skimmer, Knoblin CO2 reactor, UV sterializer 15w bulb, 65 lbs live rock, two inch fine sand, use a RO/DI for top off and water changes, feed daily with frozen food mix, use algae sheets for the herbivore fish (one 4" orange shoulder tang, one 3" sebae clown, one 2 1/2" coral beauty, one 3" foxface and just added a 2" clown fairy wrasse. Mostly soft corals with a very large frogspawn and red bubble tip for the clown.