I was wondering if green algae has any effect on the nitrates level. I have a 46 gallon bow-front tank. I've decided to let the green algae collect on the bottom (I have a bare-bottom setup) the back, and one side that's against the wall. I seem to remember reading somewhere that it can be beneficial. Also, I've seen people talk about "green water". This may be a dumb question, but is it anything beyond the obvious? Is it due to suspended algae, or green tint due to algae collecting on the surfaces?

The "green water" is due to suspended algea....I think. I'm not sure what the benefits of it are though, I think the green water is supposed to help with growht and coloration. It would seem like the algea would help keep the nirates low, but agian, I'm not sure.

The green algae that stuck on the walls (the fluffy type, not the smudge-like type) absorbs excess nitrates. I dunno if they improve growth or colouration, but famous ranchu breeder Geert Coppens prefer this type of algae over greenwater.

Greenwater absorbs all of ammonia, nitrite & nitrate, making the water pristine. It has been proved to improve growth, colouration & body shape.

I just recently started to let it grow. It's not wavy yet, but I would think it would take a couple more weeks before I can tell. When I last tried to clean it, I had to use moderate pressure with a scrubber sponge or tank scraper to get it off and even then, it took a few passes with the sponge.

What is growing so far seems to have a light green to it, about the same shade as a fresh anacharis plant. Does this sound like the "good" kind of algae?

Have a look at this page:
http://www.plantgeek.net/article_viewer.php?id=9

The good algae should be the "Beard Algae" and the bad one is the "Spot Algae"

Sediment and bacteria and other stuff collects in the algae on the floor, which is where the fish sleep in contact with it, so I'd recommend keeping the floor pristine and letting it grow on the sides instead. Just my personal belief to be on the safe side, nothing scientific.

Green water is mono-celluar algae. Which is as simple as a plant can get. One cell plants. You can get a lot of it, but it never grows bigger than one cell each. The fish actually swallows a lot of this stuff just from swimming through it and so they get a fantastic vegetable diet which promotes health, growth and colour.

The surface growing algae is multi-cellular, so it can grow in length etc. The fish tend not to eat much of it, so diet-wise it's not as good.

Either way, both types of algae (actually most plants as well) absorb the simplest forms of nitrogen first, which is ammonia. They will only consume the more complex forms like nitrite and nitrate if there's no ammonia. Which means basically that your ammonia-eating filter bacteria will starve to death and die off. Which means you'll never actually get nitrite or nitrate in full green-water. So the danger of letting algae grow profusely is that if or whenever you decide to remove it all, you may experience a new cycle in your tank as your filter won't be able to handle all the ammonia the algae were previously dealing with.

Thanks for the link. After reading that, it seems that I may have Spot algae except its in a solid "sheet" except where I scraped some of it off about a week ago. It has a slight bumpy or fuzzy feel to the touch and doesn't look or feel slimy like the blue-green type mentioned in the link. The water does have a slight green tint to it but nothing like the pictures. I don't know if it could be single celled algae or probably reflections from the algae on the side or light cover.