You may have reached a point where, even if you manage to hit the right balance between CO2, lighting, and ferts, your algae problem might not resolve itself (or take a looong time to do so) since it sounds like it's killing off your plants.
I was in a similar situation a couple months ago, maybe two weeks away from just ripping out my entire tank. I messed with fert dosing, CO2, and my light source and just couldn't shake the algae. I did a heavy-handed dose of H2O2 across the whole tank and, while it killed off some
of the algae, it also decimated my plants (so before you do H2O2, find out if your plants are tolerant to it).
Finally, I just went on winter break and killed the CO2 and lights for a full week while I was gone. I figured I was going to rip everything out when I got back anyway so why not... Turns out it was a great idea. I came back to a tank with virtually no algae. My Monte Carlo took a little bit of a hit but it's quite a hardy plant so no foul in the long term.
While this won't solve your imbalance problem, it will give you a fresh start (without ripping up your tank) so you can actually start figuring out the right balance in a relatively clean tank.
Sorry I can't offer more help concerning the balance, I know nothing about fluorescents.
That said, maybe make sure your CO2 diffuser is giving off fine enough bubbles (don't want them racing to the top) and maybe making the bubble and pump outflow paths cross.
MC is also not a low-light plant, I wouldn't be surprised if the algae is just out-competing it at that light-level.
A quick link to my experience:
Beginner creates a 10G monster - please send help
Beginner creates a 10G (algae) monster - UPDATE