Purple/red algea

[asylumdown]

Can you post a picture of the algae? How you respond depends very much on what it is you're dealing with.

Cyano is a bacteria that can be treated chemically with a product like chemi-clean. Chemi-clean won't do a thing for real algaes, diatoms, or dinoflagellates though. Buying a herbivore to eat turf algae won't do a thing for cyano.

It's best to get a positive ID on what it is first.