This Anubias var. nana is several years old and now lives in a 10 gal with a UGF. It was just an "extra" that I threw in for lack of space, and then suddenly the tank looked beautiful, so I nurtured it.
Inhabitant: one goldfish who is fed liberally. Water changed enough to keep nitrates down to the fish's comfort level. Buffered to the low 8s, because my tap water varies wildly, and while it's easy to buffer up to its highest level, it's difficult and/or expensive to soften it and lower the pH. Fertilizer is Seachem Flourish 2-3x/week cut about 2:1 with API Leaf Zone, because as you can see from the pinholes, I had a potassium deficiency going on. Light is a standard 18W plant light.
The old leaves have always been a bit light in color, but that's left over from the last tank it was in, where the problem was nitrogen deficiency. In this tank, the problem was good color and growth with pinholes, but that's kinda minor, and I dealt with it.
Forward some months to my last water change. Everything seems normal, except I've been getting some withered/transparent leaf edges on new growth since this summer. Suspecting a mystery deficiency, I'd stopped Seachem Excel to slow growth, and it got mostly better. Then something I read a couple weeks ago led me to believe it might be caused by an excess of some nutrient in the cichlid buffer, so I buffered my replacement water slightly less than I usually do.
Now you can see the photo:
This has been going on since the water change a little over a week ago. The old, kinda yellow leaves are now very yellow, and all the middle leaves are getting yellow in the center between the veins. The A. var. coffeefolia that's been struggling to even stay alive for the last 6 years put out a healthy, new leaf for the first time in months. WTF?
The same sources on deficiencies points to a magnesium deficiency. I know there's a little less than normal with a little less buffer, but I still did heavily buffer the water, and the Flourish has magnesium, as well. Is there anything else that could be causing this to happen, especially in so short a timespan? This plant took years to grow, and it looks like it's only going to take a few weeks to die! I know I have to replace it, and I do have a replacement, but it's just going to happen to the new one, too, if I don't figure this out.
Thanks for any help,