Aqueminianswered grow question 3 years ago So it depends on your reservoir size. I used 5 gallon buckets. In 24 hours my ppm would go from 900 to 1500. But that is because how much water they were drinking. I had to add water everyday. There's a certain point your plant will drink more water then uptake nutrients unless it's in a very large reservoir. When my plants were smaller ( in veg before flowering) it was very easy to balance my 5G buckets. In flowering there drinking more, if I lower the ppm they lose color, if I don't add water everyday they get nutrient burn. You sound like your in my situation. Check out my OG Diesel Kush autoflower diary. It still came out nice even though flowering was a ppm battle