MyOSD Additional parameters

What can I measure?

There are various environmental parameters, that you can measure: Air temperature, Water temperature, Wind speed, Salinity, Phosphate, Nitrate, Nitrite, pH and Secchi depth. You don't have to measure all of them, just choose which one you prefer. The only mandatory data you have to fill in to be able to upload the data is Time, Longitude, Latitude, Accuracy, Sampling depth and Sample name.

How can I measure these parameters?

Air temperature:

You can use a regular thermometer for this task or ask your weather app.

Water temperature:

Again you can use a regular thermometer, a dive computer or a clinical thermometer (usually only works with water around 30 degrees). If you are out on a (sailing) boat, check out if your boat or depth gauge has a built-in temperature sensor.

Check the water temperature


If you are on a sailing boat and have instruments to measure the true wind velocity otherwise you can also use your weather app.


You can measure the salinity with e.g. a Refractometer, a Hydrometer or a Salimeter which you might have at home if you have fish tanks.


Phosphate, Nitrate, Nitrite:

You can measure this parameter with the help of aquarist test kits for salt water which are available for just a couple of Euros/Dollars and can be used for around 50 tests. 

Test Kits


For pH measurement you need a pH meter and pH probe. Unfortunately, the pH paper tests are not suitable for salt water.

Secchi Disk:

A Secchi Disk is used to measure the water transparency in the ocean and to determine Phytoplankton abundance. It is a white disk with 30 cm in diameter connected to a rope and weighted from below. The disk is slowly lowered in the water to the point where it is no longer visible. Record this depth.

You can easily build a Secchi Disk yourself. If you google it, you can find multiple tutorials, however please note that some of them are for a black and white 20 cm Secchi Disk. For OSD, we would highly encourage you to use the 30 cm diameter disk in white color as this is often used in marine research.

How to make a Secci Disk:

  • The Secchi Disk can be plastic, metal or wood.

  • It is important that every Secchi Disk is a standard 30 cm in diameter and painted matt white

  • Attach the Secchi Disk to a long rope. For example 50 m in length

  • Mark the rope in 20 cm intervals

  • Attach a weight to your disk below using any ~200 g weight

How to make a Secci Disk

Here you can see two examples:

Secci Disk - Version 1        Secci Disk - Version 2   


Please state the devices you used for your measurements e.g. which kind of thermometer or the name and brand of the kits you used for Phosphate/Nitrate/Nitrite measurement. But also please write about interesting things you observed during your sampling e.g. jellyfish bloom or big garbage accumulation.

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