The algae on the stone may not be producing spores right now, or the spores may not adhere well to the glass. It would be best to get some algae proven to grow on glass, i.e. scrape some out of another tank. I don't know the identity of the algae that grow on tank glass. Now that you mention it I might try to get some under the scope and ID it. I'm sure there are quite a few different species that grow on tank glass, though.
thanks noto your the man, i just hope the algae that gets on tank glass will also do rocks that is why i got these rocks covered in algae in my tank was hoping it would cover glass aslo.
what could encourage algae to release spores, warm water, excess nutrients, time betwen spore releases.
That depends on the species. Not all algae even have a spore phase; certain species just spread vegetatively. I don't have any advice to give you other than to be patient, and to try introducing more algae from various sources in hopes that at least one will take off.
