Haven't seen your pictures yet, so no idea how bad the BBA is. But can you remove it manually from ornaments? Or are they growing on older leaves? With 150W on a 45cm tank, you have put yourself in the High Tech tank category, which means you will run into problems if the CO2 and Macro & Micro nutrients aren't balanced. BBA thrive in nutrient deficient tanks. This means you are either lacking in Macro or Micro ferts or both. Add to that the CO2 inject needs to be at 30ppm. Such high light is going to cause the plants to suck up all the nutrients in the tank really fast. When there is none left the older leaves suffer. BBA take hold on these older leaves first. 150W of light for 8 hours straight is also too long. The best thing I did for my tank is to get a controller that mimics sunrise and sunset with my lights. Turns on at 7am, light intensity slowly ramps up until 100% power at midday, then slowly ramps down the power to the lights until 7pm mimicking sunset. 7pm - 8pm, moonlights run, so I can come home to see my fish/shrimp after work. 12 hours of light but note: only about 1 hour of full light intensity. This is the daylight cycle. If your tank is running 8 hours of 100% power, it's very unrealistic, and no wonder algae becomes an issue in our tanks.