# Operation in a Pool Pools are acoustically quite different when compared to natural aquatic environments and are often difficult for sonar devices, including DVLs. Most pools are very sonically reflective, the reflections are usually very specular, and the reflective surfaces are many and are close to the sonar device. These reflections turn the pool into a mess of interference patterns. Pools do make convenient testing environments for robotic systems. If you need to test the DVL in a pool, you can try using the recipe below. The following command (which is the setting we use in our pool) can be sent to the DVL (without the quotes) either directly through the DVL serial or Ethernet interface or by typing it into the command textbox on the CeruleanTracker DVL command window: "MANUAL-MODE 0.001,5.0,0.5,56,0.1,50,20.6,-0.671,100,100" To revert to automatic mode, send: "MANUAL-MODE OFF" Alternatively, the DVL will revert to automatic mode if you cycle the power. The second parameter to the command (in this case, "5.0") sets the maximum range in meters. If you have a very deep pool you can try increasing this number. The third parameters to the command (in this case, "0.5") sets the minimum fly height above the pool floor, If you fly below this height the DVL will lose lock. You can try to set this slightly lower, but in no case set it below "0.3". If you are still having issues, you can tell us the symptoms and we may be able to help tweak this a little for your pool. --- # 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://docs.ceruleansonar.com/c/dvl-75/usage-considerations-and-scenarios/operation-in-a-pool.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.