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FAQ #28434

What is a secchi disk and what does it measure?

Related resource areas: Science, Engineering, and Technology for Youth


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The secchi disk is a weighted, plastic plate about 8 inches in diameter. It is lowered into the water on a marked cord until it is no longer visible. It is slowly raised until is just becomes visible. The depth of the secchi is recorded, indicating the clarity of the water. Secchi readings can vary from a few inches in very turbid water to hundreds of feet in clear lakes and oceans.

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