# What do the substrate probes measure? All of our supported substrate probes measure three key factors, giving you valuable insights into your root zone. * **Water Content (VWC)** – Measures how much water is in your substrate, helping you fine-tune irrigation. * **Electrical Conductivity (pwEC)** – Indicates the salt/nutrient concentration in your substrate, ensuring optimal feeding levels. * **Substrate temperature** – Tracks how warm your substrate is, which affects root health and nutrient uptake. ### **Why is this important?** Measuring Water Content and pwEC is essential for crop steering. It allows you to make data-driven decisions about when to water and when to feed your plants. You can access dedicated graphs for each measurement in the Grow App, and set limits and alerts for all three to stay in complete control of your grow. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://faq.growsensor.co/substrate-probes/what-do-the-substrate-probes-measure.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.