Hello, We're getting quotes for our roof to be replaced and the company we're most likely going with recommends GAF shingles that have copper grandules in them to prevent algae growth. I'm concerned because we have a rain barrel system that I use to water our garden beds, including our vegetable gardens and fruit trees/fruit tree guilds. I'm assuming that the copper granules may sluff off some material but I'm not sure how much of that occurs, and/or if it is considered detrimental to collecting rain barrel water for gardening. Do you have any insight into this? We do use mesh to stop particles from collecting in the barrels when possible but I have yet to research any other filtration system or particle mitigation.