Black spots on leaves, Algae related?

Detritus Mulm

Guru Class Expert
Jun 12, 2005
147
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I've been having a minor battle with BGA recently. The mechanical cleaning and water changes have helped with this, but it's not dead yet. I've also been having increasing issues with Green Dust Algae.

The combo was doing a number on the Rose Sword, giving it holely brown leaves. Scrubbing the leaves every few days has really improved it, but a few leaves still have black spots. These same spots are on some of the Luwigia leaves, mostly those near the bottom of the tank away from the light. I suspect the BGA is causing the problem, but I can't be sure it's not some kind of fungus or other Algae.

Background:

Light 4 wpg
CO2 15-20 ppm
Iron .2 ish
K ? Gets dosed with the Iron every week
P ?
N - Only what the fish provide, usually between 5 - 10 ppm, but falling off.