pH is at 6.2 and the gH and kH are both at 2. Light is a 2x T5HO 24" and I think 24watts each and are 16" above the bottom of the tank. On for 8 hours a day.
I have my pH at 6.0 at a KH of 2 FYI.
Same light period, likely 2x more light.
Yes, algaefix will eradicate the algae in question here.
I've not seen it NOT work yet.
Still, I've also had other tanks I've exposed my arm that had spores and threads of hair algae on it.
Some tanks got it, some did not. I noted one tank got it 2-3x, it had less CO2 than the others curiously.
Same sediment, same water, same ferts, a little less light but same type of lights, similar effects on water changes. You can prune your way out of hair algae and carefully attack and clean it out, it takes a weeks though and a lot of labor.
So back to good care and focus on the plants.
Your CO2 is not that high also.About 38 ppm.
Hair algae also prefers certain plant species.
These tend to be fine needle and fast growing weeds.
Less light can also help stop new growth of hair algae.
Which also suggest a CO2 issue.
Fast growing weeds will consume more of the CO2 than other plants and if the concentration changes during the day or much over time, then they will be the 1st to respond.
Food for thought.
So trimming the weeds more often can also help.