Hey guys. Quick question about my hydroponic setup. I check my PH and my ppm, both using digital wands. I was wondering if anyone knows why my PPM reading would go up over time. For example, my last nutrient change was 3 days ago. My plants are about 7 inches tall, and healthy. I have my nutrients at 300 ppm at feeding time. 3 days later, my PPM reading is 460. This has consistently happened to me in all my hydro grows. I am using Clay pellets as my medium and general hydroponics, grow, micro, and bloom formulas. It's all under a 600 watt MH HID bulb in a 4 by 6 by 8 grow room. The light is about 3 feet from the plant and is ventilated with a fan. Thanks for the help guys.