If you can't get your hands on a scope and you want to know when to flush, start now considering you're near or past day 50. If I were you, I'd be plain watering now till the end. I like to add carbs, like Bonicare Sweet and PurpleMax or Snowstorm ultra along with water correctly PH adjusted till at least day 60. They will swell up a bit the last 2 weeks, hairs will turn orange and trichs will turn cloudy then amber.