Thanks! I hope the tank continues to improve, Murphy's Law and all. Thanks to the incredibly knowledgeable people on this forum I have so many tools to deal with issues that come up now.
The substrate is
#1 40 pounds of medium gravel purchased when I first set up a planted tank in the 1990's.
#2 Schultz's Aquatic Soil purchased when I was reading APD and learned about CEC in the first place and set up a 150 gallon tank in 2000. I think it was 40 pounds.
#3 Pea sized gravel that came with the 180 gallon tank and I needed more substrate last year. 4 trash bags, maybe 150 pounds. The larger pieces were sifted out when I set up this tank. I rinsed and bleached it because I didn't know the fate of the fish in that tank.
#4 SafeTSorb that replaced the large gravel sifted out. 40 pounds.
#5 Mulm that has never been rinsed out of the substrate.
#6 Clay+NPK+micros root tabs I made this year.
It all comes to about half high CEC clay substrate and half natural gravel by volume. The combination is quite natural looking.
Lit with 2 fishneedit 150 watt metal halides hung ~40" off the substrate last time I measured. The bulbs are ADA NA 8000K, not the green. Currently 8 hour day and I am shading with window screen for part of the day still. The plants are improving in size and color as I increase the light. I probably won't be lowering the fixtures after the window screen comes off.