Algae functions as plants?

I have had a tank for a long time, but never started reading about it until now. I have a 75g(soon to be two 75g tanks connected with a water-bridge) tank that has 1 10" yellow bullhead, 1 5-6" green sunfish, 1 4" dollar sunfish, 1 3" unknown sunfish(prolly a green hybrid, and 1 6" koi that will be moved to a pond when it gets too large. I also have a couple different varieties of snail in the tank(koi and green sunfish eat them). I originally had plants in the tank, but the snails and fish selection I have destroy plants every time I put them in the tank. About the past 6 months I have just let algae grow on the back wall of the tank for 1) food for the snails and koi, and 2) thinking that the algae could actually function as the plants would. The algae is a mostly green layer on the glass that the snails love to eat. It doesn't seem to extend into the water or discolor it. Is the algae harmful or beneficial to the fish at all? What does it do to the water chemistry? Like I said, I'm not a new tank owner, just never was informed on any of this stuff. Thanks in advance, -Tbird-

Yes algae does function much like a plant and will consume the nutrients (nitrates) in the water, provides a food source, and consumes co2 to produce oxygen when light is available. Most people simply do not like the aesthetics of algae in a tank. The algae does not harm your fish and does helps maintain water quality. The only thing to be concerned about is if an excessive amount of algae starts dying it will decay and release a lot of ammonia and nitrates while the process consumes oxygen. This generally only happens if the initial nitrate levels are very high, producing an extensive algae bloom, which then consumes the nitrates to the point that the algae bloom gets starved out and dies.

It sounds like, from your description, that your tank is fine and benefiting from the algae growth, pretty much as you assumed. Much like a tank benefits from plant growth. Just keep the algae levels within reason to avoid a die off and the cascade effect that can follow. A thin layer on the glass is well within reason. The removal of excessive algae also removes those nutrients, much like a water change.

Thanks a lot for the info, I only let the algae grow on one wall of the tank, and it doesn't get very thick cause the snails and fish eat it. The fish seem to like it just fine as a backdrop, and I think it looks just as good as having paper behind the tank. Thanks again for your help, -Tbird-

I find a small bushy mass of algea provides a nice spawning ground for banded killifish as well.

check out algaescrubber.net

basically the idea is to force the algae to grow on a screen out of site, so it isnt in your tank. This way the algae is out of site, but you still get the benefits of the algae. I have my algae scrubber in my sump. My tank is clean and has no algae, but there is an ugly mess on my scrubber that i clean weekly.

I have a algae growing over almost al of the rocks in my 75 gallon tank. It's not the slimy kind though it's more of a feathery mossy kind that looks very good and very natural.