I reuse coco and replace it once a year, the last two weeks of a plants life in my garden they get calmag water only so once the roots have been removed it's already good to go again. I spent roughly 140$ for coco and perlite for this grow season, old gets mix with new until its all been run 3 or 4 times, you bet I'll reuse it for as long as I can to help the price per gram to be as low as possible.