Put your puter at 1.4 like the rest of us do unless you have a good reason for it. the idea of being extra safe by using 1.2 is an over reaction. MUCH LIKE PUTTING ON A SECOND SEAT BELT in your car. Next see what your setting is for 33/34 fresh or salt water or en##### and if available what your surface pressure is set at if it has that setting. the dangerous part of the ppo2 curve is at about 1,65. 1.4 provides plenty of safety margine.