Have just read both manufacturers algae warranty section. OCF offers a 5 year warranty against algae streaking; CT 10 year. However, OC is only a full 1 yr non-pro-rated warranty. Years 1-5 are pro-rated on a depreciating schedule. CT offers a full 5 year. Pro-rated years 5-10. It is interesting that the acknowledge the problem. And will pay for the cleaning of the roof using approved methods as outlined . No power washing.
These shingle warranties are pro-rated,excluding labor and you must buy thier shingle at manufactures list price buy the time your done its cheaper to buy the shingles at a supply house