So I Figured It Out
When no one replied to my request above for help, I had 3 thoughts.
1. No one likes me
2. The above looks good and no one has a clue either
3. It’s such a disaster, no one wants to deal with it.
I was reasonably confident it wasn’t #1, and I knew my parameters looked good, but I was out of things to try. My tank was getting worse and worse, and nothing was working.
The answer was, none of the above....

It was my temperature.
When I originally set this up last year, I had an Oase thermo filter. It was set to 79F which seemed too hot. I have no livestock, and after posting about it, everyone agreed I could turn it off. Later, I switched to a smaller filter without a heater.
As the weather cooled, I grew tired of putting my hand into cold water. I have ice cold hands already. I ordered a heater, ironically
only because my hands were getting cold. In the days waiting for it to arrive, it occurred to me, maybe my water was too cold for the plants. Could the cold be slowing their metabolisms to below optimal thus preventing them from fighting the algae? I got really excited. I never check my temp, and my thermometer said 17C (62F). My house isn’t that cold, but the tank is on an outside wall near a window. Through a search I found some
anecdotal info about planted tank temps and got optimistic that this could be it.
Interestingly, in addition to the algae, my tank had almost stopped pearling despite plenty of fertilizer and CO2. Within 24-48 hours of getting the heater, the water was back to looking like champagne.
Ironically, I’ve wondered for weeks if my problem was that I didn’t have fish. In tanks with fish, the waste nutrients might be the little something I wasn’t getting. In a way, it’s true. If I had had fish, I would have had a heater.
I hope to post a picture soon and update with what I'm doing. Things are turning around fast, but I', having a had time doing maintenance. We got a major part of the remodeling finished, but there is a lot to clean up.
This is a good lesson for us all. It's not always the
NO3, light, or CO2.