no, no no.....After you take the measurements times 5, you need to apply a 1.33 correction factor if you are using it underwater. There is also a chart of other correction factors based on a specific light source on page 14 of the manual on the Apogee WebSite.
The Apogee Full-Spectrum Quantum Sensor (model SQ-500) is more spectrally accurate than the Original Quantum Sensor (model SQ-120), but the unique optics (mainly the shape) cause the immersion effect to be larger for the new sensor. Underwater PAR measurements collected using a full-spectrum sensor can be corrected by multiplying by 1.32;
measurements collected using an original Apogee sensor should be multiplied by 1.08*.
Okay, so then multiply the raw par from the 120 by 1.08?