FreshwaterFishie
Fish Fanatic

OK, I looked at some freshwater plants. I think it might be a species of Sword. I am pretty sure it is a mid-ground plant.
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Most swords will want moderate light to grow. A few will survive in lower light. Brown algae is not algae at all but diatoms, which are usually found in low light tanks. Thus, I suspect the problem with your plant is that you do not have enough of the right kind of light for it.
Assuming you have a moderate sized regular shaped tank, you will want 2Watts per gallon of full spectrum, (5000K - 6700K), fluorescent lighting turned on for 10-12 hours a day to get "Moderate/Medium light.
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