For Copper Power, it's about 1 mL per gallon to get 1.75 ppm. Here is a link: https://www.reef2reef.com/threads/ratios-for-dosing-copper-power.385871/
For checking the current level: if your checker only measures up to 1 ppm, mix equal parts tank water with RODI. Then check the result. That should get the reading under 1ppm. Then multiply results by 2.
For checking the current level: if your checker only measures up to 1 ppm, mix equal parts tank water with RODI. Then check the result. That should get the reading under 1ppm. Then multiply results by 2.