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 soften the water in my Hot Springs Spa? How long should I wait before using my spa after I have added chemicals? What is Nature2 Spa Stick? Comments 0 comments Article is closed for comments.