Voted bla myself. I have a java fern that does exactly the same thing. It is attached to rocks in an african cichlid tank, lighting is low/mod (2 t8 bulbs over a 75 gallon tank). Java fern grows as does anubias however the java fern gets brown spots on the leaves and then they drop off after turning brown. I've tried everything from changing light bulbs to stopping water changes to see if the increase in nitrates helps, no change. I'm now experimenting dosing with iron to see if that helps.
Hi nonamesleft47
There is a big difference between my plant and yours. The leaves were not getting worse than on my first photos. They wouldn't turn brown and drop off like yours. Actually leaves on my plant rarely die. They just had the brown spots and apart from that the leaves were strong and healthy. On the diagram posted above (thanks Fyurae) my plant plant problem is still not identified or maybe could be a mild phosphate deficiency :huh:?
I think only time and eliminating possible factors one by one will tell... Or someone who had this exact problem before.