I usually would change 20% every other week. My pump that does water changes for me broke so I haven’t done one in the past 3 weeks.@Lasse
If that’s regular hair alga. Does it spread like other algae? Can the rocks be scrubbed In tank? Or would that just make it worse? Of course a large water change would need to be done afterwards to remove as much as possible. Or is it safer to remove rock and scrub?
@Chris_Noles What’s your water change routine? Smaller more frequent water changes would be good.