Lights on way too much 12 + hrs, tank is about four months old, I test weekly have done nothing but top offs for about a month maybe six weeks.
my substrate is filthy but I don’t feed my real plants macro nutrients
At 4 months old, diatoms are very normal those should settle down overtime.
I would do full on water changes and gravel vacuum every week to remove excess organic matter from the substrate, and excess bacteria growth as well.
And reduce your lights to 6 hours a day.
Basically limit the excess organics available to the algae, limit the light period (6 hours is fine for the plants, but not enough for algae to really get a hold with), and you should see it reducing with maintenance.