Old sand can be one cause of algae. To be fair, Albert never said, you can can't have a clean tank with sand. I took his post to be tongue in cheek anyways.
As I read the thread, I'm reminded of the Propositional Fallacy that I learned many years ago. I think it is was called Denying the Antecedent.
I did actually replace my 14 year old sand with new sand after years of battling hair algae and dinoflagellate with regular water changes, gravel vacuum, cleanup crew, algaecides, protein skimming, Chemiclean, etc. Nothing helped. Now, problem gone.