Don't be afraid of hair algae, but do be cautious. If you really want to, you can make it work. I haven't tried it in a fish tank, but the way it grows in my pond couldn't please me more. The main thing about hair algae is knowing how to control it. My pond is roughly 700 gallons, and there are at least 15-20 gold fish living in it. The
goldfish are what I use to keep the algae in check.
However, without the goldfish, the algae would be a huge mess. The other thing to worry about is algae messes with the
pH of the water, too.