Is ANY algae growth normal??

[chem geek]

Usually it's metals, but it can also be algae. Usually if it's a clear green it's metal while if it's cloudy or dull green it's algae. Remember that colors can fool you since a yellow color (such as from iron) against a blue pool surface will look green.

 

[linen]

Thanks for the confirmation. I have always assumed tinted (but clear) fill water was metals, but this discussion had me second guessing that.