It ended up being 2 issues.I only read the couple first pages, but I think the problem could be that you are way underpowered in the lighting. Lights are necessary to a balanced ecosystem, and if you are at 160ppm nitrates but have zero algae on your rocks, glass or sand, then lighting is the first thing I would look at. Algae isn't a bad thing, even if it's undesirable, but I can't imagine what else would be limiting in the face of high nutrients.
1- Fish deaths were due to Uronema (I mis-diagnosed first Chromis death)
2- Lights were underpowered
So yes, you are correct lol.