Thank you for your response! The WCMs are temporary and will be replaced with 2 african dwarf frogs, a nerite, and a betta once I get the green light from my LFS (betta will be added a couple days after the others). I originally had the temp in the low 70s but saw my anubias suffering, and my LFS suggested to adjust the temp and my anubias has been happy ever since so I am hesitant to lower it again, especially since the minnows don't seem to mind at all. They are very lively and cute to watch.
I'm starting to think bacteria came in on the plants and that they & the plants simply support the bioload pretty well on their own... I *think* I see brown algae on this leaf ornament I have suctioned to the side (a cute "betta hammock" that they apparently love according to many reviews & posts) and I heard that was a sign that a tank is newly established? I only noticed it a couple days ago and then rubbed it off.