Thanks for the reply. When adding water to the resevoir, how far should the ppm be able to drop from the setpoint before adding more nutrient to jump it to the correct level? lets say its at 1000 ppm to start, then water level drops an inch and after the water fill its at 950ppm, should it be corrected to 1000 right away or should the nutrients be used up first and then be replenished?