We had a deck built in 2017 using TimberTech grooved composite planks. Earlier this year I noticed some white streaks on 2 planks. Based on Timbertech care and cleaning guide, I used luke warm water and a nylon brush to clean the streaks but it didn't make them go away. Recently I noticed several more planks are showing white streaks and spots. We live in San Francisco Bay Area so the deck never had snow on it. Does anyone have this issue with a 5 or 6 year old TimberTech deck?