I have officially upped my game. Here is why and how.
I have positively identified the snotty looking brown gunk as dinos. Here is what they looked like under the microscope at 400X.
The basics of what I am doing now is H2O2 dosing with 3% food grade Hydrogen Peroxide. I am going to start dosing 1 mL per 10 gallons, try that for several days, and double it if it is ineffective. I just started dosing yesterday, and so far, there has been no change. Here is the cheap microscope I bought on Amazon, and also the Hydrogen Peroxide I bought online as well.