> From: Stephen.Pushak at saudan_HAC.COM > > George, does the daily dosage for Dupla drops aim for a .1 ppm > concentration or somewhat lower? Dupla doesn't specify how much is needed but their 10,000 liter demo tank has 0.08 ppm and we try to maintain around 0.1 ppm. If we get close to 0.15 ppm, thread algae starts to appear. George in the Very Dry Colorado Front Range