The storage flux term, added to the turbulent flux estimated by the Eddy Covariance (EC) system, allows for a closer quantification of the true net ecosystem exchange (NEE) of a given scalar (e.g. CO2, H2O, CH4, N2O, temperature) The storage flux of a given scalar C is given by the vertical integration of the scalar rate of change within the control volume. It is measured by sampling a number of points distributed between the ground surface and the measurement height of the turbulent flux, the number and location of which depend on the specific ecosystem and the chosen measurement strategy. Sc measurements for CO2 and H2O are mandatory for stations where the EC system is placed at a height of 4 m or above. They can be either mandatory or only recommended for tower heights between 2 m and 4 m depending on Sc relevance (to be agreed with ETC). They are also mandatory for CH4 and N2O at stations where EC measurements of these two gases are performed, and following the same measurement height requirement as for the CO2. This document reports the instructions for the storage measuring system setup in ICOS stations, describing the steps needed from the installation of the sensors to the data collection, including maintenance, calibration and data submission. The info is contained in the following sections: - System setup: in this section the sensors are described, and the steps from the installation to the data collection are illustrated. - Maintenance: in this section all the maintenance and calibration guidelines are described, including the general timeline and how to deal with repairs. - Submission: it is the section related to the data preparation and submission to the ETC. It includes a summary of the submission workflow, better described in the dedicated document, and lists all metadata and ancillary parameters to be sent at the ETC, and how to submit them. It is important to remind that the exact application of the protocol/instruction must be also discussed with the ETC in order to reach agreed solutions for specific cases. If a specific part is relevant only for a specific ecosystem or station Class this is also reported in the document.