i am afraid that is a pretty bad case and until you can even things out you are going to have to trim off the worst leaves. i could be wrong but as long as you're not trimming enough to endanger the plant or seriously stun it you will be seriously reducing the amount there is to reproduce. although i will never suggest it my anubias nana has grown back from only having 1 leaf so they are pretty hardy. i just wish i hadn't thrown out the other plant now. i have to admit it now... i was a dummy and fastened the rhizome down too tightly with a rubber band and it melted. that's how i wound up with 1 leaf per plant (i got them barely with leaves anyway).
now if a blackout works i would say don't trim as the more leaves you have taking in light and nutrients the better off you are.
I've been experimenting with my anubias by putting Melafix on the leaves. I took the plant out, scrubbed the algae off with a toothbrush, and then wiped the leaves dry. Then I apply some melafix to a paper towel and wipe it on the leaves. the first time I did it, the leaves stayed clean for a little over a month. I just did it again this weekend and I only put it on half of the leaves just to see if it was actually doing anything or not.
I read in Amano's TFH article a couple of months ago that he uses some sort of natural antiseptic or something to prevent algae on the leaves. I haven't been able to find out exactly what he was talking about, hence my experiment with Melafix which has tea tree oil in it.
I'll keep treating with Excel this week and if nothing gets better I'll do a 3 day black out. If that doesn't do anything I'll trim off the bad leaves.
When I first bought this anubias I cut it in three pieces. Each piece had three leaves but The first one I cut didn't have any roots coming out of the rhizome. I thought I had killed it. Now all three pieces are triple+ the size from when I cut them. I do wish I had purchased a "nana" rather than the "barteri" thought. My tank is too small for the barteri to look good IMO.
An update on a little progress.
Here are two photos.
From the start of the algae problem.
After some Excel and H2O2 treatments (July 1, one photo with flash and the other without).
3 days from the former photo with continued Excel treatments (July 4, one photo with flash and the other without).
Improvement. I have also seen some thread algae mixed in with my java moss and I am manually removing that and treating some other leaves on my crypts. with the Excel and H2O2. Now I am going to do a thurough cleaning on the glass and filter pipes to get the GDA off. I'll update with more photos of the whole tank later.
Thanks for all your help and advice, everyone.