What colour is algae? Sherralyn October 01, 2018 23:24 Updated Follow Algae can come in several forms. Pink, green, yellow or brown film or slime. We suggest using Poppits Pool Algicide to get rid of it. Related articles How do I switch to BioGuard Armour if I have been using Lithium? What is your Return Policy? Comments 0 comments Article is closed for comments.