Question 1

What is the best nitrox mix for 30 meters / 100 feet?

Accepted Answer

At 30 meters (4 bar absolute), using a PPO₂ of 1.4, the optimal Nitrox mix is EAN32 (32% oxygen). This gives you the maximum bottom time advantage while staying within safe oxygen limits. At this depth, EAN32 has an equivalent air depth of about 21 meters, significantly reducing nitrogen absorption compared to breathing air.

Question 2

How do I calculate the optimal oxygen percentage for my depth?

Accepted Answer

The formula is: Optimal O₂% = PPO₂ ÷ (Depth ÷ 10 + 1). For example, at 24 meters with a PPO₂ of 1.4: O₂% = 1.4 ÷ (24 ÷ 10 + 1) = 1.4 ÷ 3.4 = 41.1%. Since standard Nitrox blends are typically sold in even percentages, you'd use EAN40 for this depth.

Question 3

What is the difference between MOD and best mix?

Accepted Answer

MOD (Maximum Operating Depth) is the deepest you can safely dive with a specific Nitrox blend without exceeding your PPO₂ limit. The 'Best Mix' is the highest oxygen percentage you can use at your planned depth to maximize bottom time. The best mix is always at or below the MOD for your chosen PPO₂.

Question 4

What PPO₂ should I use for recreational Nitrox diving?

Accepted Answer

Most recreational divers use a PPO₂ between 1.4 and 1.6 bar. 1.4 bar is considered conservative and is recommended for longer or deeper dives. 1.6 bar is the maximum allowed by many dive agencies for a single dive, but it should only be used by experienced divers at shallower depths.

Question 5

Can I use Nitrox at any depth?

Accepted Answer

No, Nitrox has depth limitations. Each blend has a Maximum Operating Depth (MOD) based on its oxygen percentage and your chosen PPO₂. Diving deeper than the MOD risks oxygen toxicity. Conversely, using very high O₂ mixes at shallow depths is safe but offers diminishing returns on bottom time benefits.

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