What Fert Deficiency on my Anubias is this?

[frothhelmet]

The brown areas on the leaves started appearing recently. The leaf with the huge brown area is about a week old and the brown-ness appeared a couple days ago. The other leaf turned a bit brown a few weeks ago.

The tank is 20l, I have 3l of ADA Amazonia I. It is low-tech, I do ~20% WC/week, I add no ferts explicitly except in shrimp and snail food.

 

[Arana]

image is not showing for me :?

 

[a1Matt]

I could not name the exact deficiency with accuracy, but I'd say it is definitely one of the macro nutrients (n, p, k).
Possibly all 3.

Either way dosing all the macros is a good step to take.
or overfeed the tank, but I do not think you have sufficient livestock to do this without unbalancing the tank.

Adding ferts will not help the leaves that are already affected.

 

[ghostsword]

I would say nutrients as well, especially as the Anubias get their nutrients from the water column and not from the subtrate.

If you look at the lily at the back, it looks very healthy, probably getting all the good stuff from the substrate.

 

[Gfish]

I agree, I had similar looking leaves on mine after about 6 to 8 weeks in the tank. And it started when I increased filtration.
All is good now and im chucking in loads of dry ferts so new growths good too.