High Light vs Photoperiod vs distance (PAR)

[sundragon]

How do I get my lush hairgrass back?


So I've been running my tank for about 8 months:

I had an outbreak of hair algae when I first set up and realized my lights were waaaay too close to the surface. I hiked them up and now they are 33 inches from the substrate and 16 inches from the surface of the water. I also did a blackout that wiped out the algae (along with my tiger lotuses)

I then got the ferts wrong and had a nice outbreak of BBA which was a pain to get rid of, but is nearly non existent after a month thanks to Excel and regular water changes.

57G 36x18x21"

Lighting
I have 4x 39W T5 HO bulbs running in two separate banks.
I currently run one bank of light for a total of 6 hours. (14:00-20:00).
I run the second bank of light for 5 hours (17:00-22:00).
78W for 8 hours total, of which 156W for 3 hours (when they overlap 17:00 - 20:00).

CO2
I run pressurized CO2, and ferts - everything grows really well - The reds are starting to pop on the plants that are near the surface and staurogyne repens is growing like a weed but the hairgrass...

The hairgrass is alive, but quite thin compared to when the light was closer (When I set up the tank).
I do not want to have an algae outbreak again so I'm toying with dropping the light an inch to increase the PAR value at the substrate surface, alternatively, I can increase the photo period or the amount of light

I've read that dwarf hairgrass likes 2WPG or more. That being said, I know to focus on PAR vs WPG as a measure of effective light.

So what's the recommendation? I won't do any drastic changes - one nudge and wait, another nudge and wait...