Why is algae bad?

[Chocobo]

I have seen numerous threads talking about different ways to prevent algae buildup in waterers but I can't seem to find any information on why.
What is it about algae that is so dangerous to chickens?

 

[Mahonri]

I don't think that algae in itself is bad, it's the other micro organisms that are harbored with it that can cause infections etc...

I regularly take a supplement that has algae in it so I know it's not bad for consumption.

 

[allpeepedout]

Common algae releases a host of toxins that can be harmful to humans internally and externally, at a certain level, and I presume possibly also chickens. It rapidly fouls the water (creates a stench), which tends to discourage drinking. Clogs automated systems.

The previous poster may be referring to consuming spirulina, a variety sold in health food stores. Perhaps there is a distinction between the algae itself and the waste it produces.