Filefish are for sale anyway lol nudis took off in another tank so moving them to add nudis. Windows have been open recently minus hotter days/parts of the day. I do not have a controller so can’t constantly monitor ph but windows open definitely helps my ph I noticed when testing in the past. I’ve been thinking about the line outside to skimmer just haven’t gotten there.Try opening windows and running an airline from your skimmer to increase PH. My Ph when the house is sealed is low 8s but when windows open I get to 8.3 ish (IMO a sweet spot). PH probes can expire and need to be replaced (I've been told). Regular calibration every couple months is necessary too.
Also, my Filefish was fine until he wasn't. Just saying.
When you say consumption...do you mean that your corals arent uptaking ALk and Calc? maybe mag is low? try boosting to 1400.
Are you test kits new? old? maybe take samples to a fish store to have them double-check. something ain't right!
Last time I tested I did first day then four days later or so and alk ca didn’t change. Mag is typically around 1400. Not old test kits and even have a backup alk kit to verify.