Just a short update: I installed an Eheim spray bar (great quality!) and an inline Up Aqua Atomizer. I think this has been one of the best investments so far. Yesterday, all of my plants were pearling for the very first time, including my HC. I can see tiny CO2 bubbles throughout the ENTIRE tank. It even gets to the bottom where my HC is. I absolutely love it, wish I had done this from the beginning. Only the front left corner doesn't get as much CO2 but I'll probably drill a small hole in the spray bar directly above it.
How long will it take for my HC and stunted P. Stellata to really start growing?