Ok, I backed the light all the way back to 10% during the day.
Installed my second heater, a filter sock, my pH probe, a thermometer, and got my alkalinity test kit and HANNA PO4
checker in today. pH meter is reading 8.3 which matches my titration test results.
The brown algae, whatever it is (I think it is diatoms, but it looks like it might be kind of stubbly so hope it isn't something else) definitely spread a little more today while I was gone. Is it possible it is dead or dying coraline? It looks like it is just growing on top of my LR
that I purchased, and on top of the coraline that was already there.