I've been reading about using mangroves for natural nitrate reduction. What are they and how do they work?
They are a plant but they naturally grow out of the water so aren't the greatest choice for a tank to be honest. I prefer to use Chaetomorpha sp. algae for nitrate reduction. It's very hardy and very easy to grow.
should be fine for the Chaeto. The 'pods will love it. They'll hide in it and you'll get loads!