Here are five reasons to dive with enriched air nitrox:
1. Longer Bottom Times: Recreational nitrox (21 - 40% oxygen) contains a lower percentage of nitrogen than air. The reduced percentage of nitrogen in recreational nitrox allows divers to extend their no-decompression limits(or dive time) by reducing nitrogen absorption – the less nitrogen there is in a diver's breathing gas, the slower his nitrogen absorption will be at a given depth. For example, according to the NOAA (National Oceanographic and Atmospheric Association) no-decompression dive tables, a diver using Nitrox 36 (or NOAA Nitrox II) may stay up to 50 minutes at 90 feet of sea water, while a diver using air may only stay a maximum of 30 minutes at this depth.
2. Shorter Surface Intervals: A diver using nitrox absorbs less nitrogen for a given depth and dive time than a diver using air. This means that the nitrox diver has less nitrogen to off-gas during a surface interval, which can shorten the required surface interval drastically. For example, a diver using Nitrox 32 (NOAA Nitrox I) can repeat a 50 minute dive to 60 feet after 41 minutes, while a diver using air must wait a minimum of 8 hours to repeat the same dive (using to NOAA's no decompression dive tables).
3. Longer Repetitive Dive Times: Nitrox becomes especially useful for divers who engage in more than one dive per a day. A diver using nitrox will have a longer allowable bottom time on a repetitive dive than a diver using air because the diver using nitrox has absorbed less nitrogen. For example, after a dive to 70 feet for 30 minutes, a diver using Nitrox 32 can stay at 70 feet for a maximum of 24 minutes if he immediately reenters the water. However, a diver preforming the same series of dives on air may only stay at 70 feet for 19 minutes on his second dive (according to NOAA's no decompression dive tables).
4. Reduced Exhaustion: Many divers claim to feel less exhausted after a dive on nitrox than after a comparable dive on air. By reducing a diver's nitrogen absorption, nitrox may also reduce a diver's post-dive exhaustion.
5. Shorter Decompression: Technical divers use nitrox to reduce decompression requirements. If nitrox is used throughout the dive, the diver may require shorter or fewer decompression stops. If nitrox is used as a decompression gas (the diver only breathes nitrox during the decompression stops), the decompression stops will be shorter.