I like that old people dry humor. Once you realize they are only half serious at best it becomes way more fun to talk to them.Funny you mention 3s. Quick story that happened the other day. My Gals Mom who lives with us is 86 with Parkinson's and dementia, she isn't really mean but says some random things. Recently my mom fell and broke her hip and while in a facility for rehab my Dad ends up on the floor then ER and is now going to be admitted to the same facility my mother is in. I get home from making my rounds the other day and my Gals Mom asked me how my parents are doing so I explain knowing she isn't going remember anything. She looks at me for a few seconds and says "well maybe you'll be next"She's a believer in the bad things happen in 3s things also. She's a funny old gal in her own way.
On another note I'm happy to report what ever is going on in tye tank seems to have paused or one if the few actions I performed earlier had an effect. What ever it is it hasn't spread any further. I lost the digi but that was the last piece. I did not dose chemiclean. Fingers crossed every morning when I do my inspection. I removed all of the affected pieces and am just monitoring things.
That is good news about the tank! I think personally that 1 of 2 things happened. That either there was some sort of imbalance that caused the scales to tip out of your acro's favor and carbon and water changes helped clean it up, or 2 that it was that leather that poisoned them and the carbon and water changes helped clean it up.
Almost all the time RTN is a chemistry issue. Even sometimes when it is bacterial, the cause is chemistry. A lot of the bacteria in our tanks can be healthy and beneficial, until something flips that switch and the same bacteria becomes detrimental. Either way, a large water change and some carbon can go a long way.

She's a believer in the bad things happen in 3s things also. She's a funny old gal in her own way.