OK, here's what I think you have going on. First, lets start with your lighting level. From the LED Lighting Compendium on this site:
PAR Values
Values between 10-30 are considered low light.
Values between 30-80 are considered medium light.
Values between 80-120 are considered high light.
Finnex Ray II
PAR Data(Source) PAR vs. Distance from source
16" fixture: 130 PAR @ 6", 49 PAR @ 12", 27 PAR @ 18"
18" fixture: 153 PAR @ 6", 72 PAR @ 12", 37 PAR @ 18"
24" fixture: 179 PAR @ 6", 87 PAR @ 12", 55 PAR @ 18"
36" fixture: 193 PAR @ 6", 96 PAR @ 12", 77 PAR @ 18"
The PAR values in bold (for the 36" fixture) are approximations by me since they weren't available in the compendium. Also, the compendium doesn't provide any PAR values over 18" away from the fixture. So that will have to be approximated as well. Based on the PAR degradation with distance that is reported, I am going to assume a value of 58 PAR at a distance of 24". Since this isn't exact, let's use the range of 55-65 PAR at 24". This still isn't as far away from the substrate as your light currently is, but it's close. From your raised light to the substrate, you're likely to be in the 40-60 PAR range, which would put you in the middle to upper-middle part of the medium light scale. At this lighting level, you are going to need ways to control algae, as you've seen. But you're still not in the high light/high tech category where you see super fast growth and plants use lots of nutrients quickly. You're somewhere between that and low tech. Even though you have some fast growing plants, you also don't have a very heavily stocked aquarium to suck up nutrients away from algae.
So, with all of that, my suggestion would be to go back to your fert dosing schedule of the first couple months. That's the recommendation for a 20-40 gallon aquarium. You also mentioned that you tested the phosphates to be over 10 ppm. Have you checked your tap water to know what you're starting with? You may have had a high phosphate reading because you're adding too many ferts for your aquarium. Which in turn has caused the algae problem.
The last piece of the puzzle is the CO2. Do you know how much you're adding to the aquarium? And what method are you using to get the CO2 in to the water?
From what I see, you seem to be stuck between a low tech and a high tech approach. If you're going high tech, then get a CO2 drop checker and slowly adjust your CO2 addition to an optimum level. I'd also recommend lowering the light back to tank level if you go this route. If you want to take a lower tech approach, keep the light where it is and go with 1-2 bps on the CO2 and call it good. I think the biggest issue though is the amount of ferts you've been adding. I add the same amount I recommended to you to my 55 gallon low tech aquarium. And it has a lot more plants in it. Well, that is when I decide to add ferts. Since it's low tech and heavily stocked, I don't worry about it too much.
Anyway, that's my thoughts on the situation. Hopefully I didn't get too long winded and actually made some sense.
