A question from a fellow grower:
can you help I have a dwc first time the ppm going in is 400 and the runoff is 300 does this mean that it needs more food or am I ok
IN general. If your runoff is lower than your adjusted ppm, then the plant is drinking more water than nutrients, and this means the solution is too strong. ON the other hand; I question whether or not you have an issue.
You gave us no info in order to make an informed decision, or to really help you. Perhaps you can elaborate on the details of your grow set-up. 