Decreasing ferts really doesn't help algae issues. Any algae can survive on the most minimal ferts so all you would be doing is weakening your plants. Try putting your CO2 on a separate timer and start it an hour earlier than the lights. I think a 8 hour photo period is fine. I would try increasing CO2 slowly. Your lighting isn't that high so, I would leave that alone for now and work on ferts and CO2. Crypt Parva is a slow grower so, it will be tough to keep algae from growing on it. You could find a way to shade the Crypt Parva slightly, maybe with slightly taller faster growing plants.Should I cut the light intensity, i.e go from 2 light fixtures to 1, cut the photoperiod, or both?
I should have given more info on the tank as well..
The co2 goes on/off with the lights. I haven't been keeping up with the ferts lately either. When I was dosing the full line of Seachem ferts, I had a problem with both gda on the glass and what I am currently seeing now. After giving up on ferts, gda is gone but this brown stuff on the c.parva wont go away and comes back after removing as much of it as I can find.
Perhaps when I was dosing ferts, I was giving too much or not enough?
Thanks for the help!