Thanks, all, for the help. It kills me to lose a living thing in my care, and I especially loathe it when it's due to my ignorance, so as much as I know sometimes it's going to happen, I hope I can do what I can to forestall any more losses.
I also hope I'm not overthinking this. Is this reasonable?
My usual schedule is:
50% change day on Sunday, macros; excel at 4 ml for the tank
Monday, micros/traces/iron;excel at 2 ml
Tuesday, macros, excel at 2 ml
Wednesday, same as monday
Thursday, same as Tuesday
Friday, same as Monday
(Thanks, Hoppy, on the water change % correction - neglected that I am using old water as well as new): So, planning a 1/4 water change Sunday, Tuesday, Thursday, and every morning doing 1/6 the weekly micros/traces/iron, 2 ml excel, and every afternoon 1/6 the weekly macros, for 3 weeks. Hoping this is a reasonable approach.
Also, Marrow, thanks for the extract notion - I've seen very little on this, but I'm intrigued. I also have to keep in mind the white clouds in there - don't know how these interact with the blackwater material, but will investigate. My hunch is that I will have to do what I can to gently coax these guys to work with my parameters, rather than trying to micro-manage the parameters to them, because without getting extremely precise, and monitoring constantly, I think I'm concerned more with variations in water chemistry on an ongoing basis than going with the one constant I do have, which is my water supply (absent RO and precise ion dosing, that is). Hope that makes sense.