Tank Configuration
The tank configuration section sits below the depth and time inputs. Here you define the gas supply for your dive, from a single recreational tank to a full technical setup with multiple bottom and decompression gases.
Adding a tank
Click Add Tank to add a new tank to your dive plan. Each tank has the following settings:
| Setting | Description |
|---|---|
| Model | Pick a standard tank from the dropdown (see below) or Custom… to enter a raw volume |
| Start pressure | Fill pressure (bar or psi depending on your unit system) |
| Reserve pressure | Minimum pressure at which the tank is considered "in reserve" |
| O2 % | Oxygen percentage in the mix (21% for air, higher for nitrox) |
| He % | Helium percentage for trimix blends (0% for air/nitrox) |
Tank model picker
Instead of typing a raw volume, you pick a standard tank name. The list is filtered to your active unit system:
- Metric — European tanks named by water volume:
2 L,3 L,5 L,7 L,10 L,12 L,15 L,18 L - Imperial — US commercial names shown with their metric equivalent in parentheses:
- Aluminium (Luxfer / Catalina):
AL13,AL30,AL40,AL63,AL80,AL100 - Steel HP (rated 237 bar / 3442 psi):
HP80,HP100,HP117,HP120,HP130 - Steel LP (rated 172 bar / 2400 psi):
LP45,LP65,LP85,LP95,LP108
- Aluminium (Luxfer / Catalina):
- Custom… — always available; enter any water volume in your unit system
Pressures are not pre-filled — the planner deliberately keeps them empty (with placeholders like e.g. 200) so you enter the actual fill pressure of your tank rather than a generic default.
When you switch between metric and imperial from anywhere in the app (a per-field toggle, the plan settings, or your diver profile), the tank list and every value in the planner switch too. See Metric ↔ Imperial units for the full behaviour.
Saving your favourite setups
If you regularly reuse the same tank + gas configuration, save it as a preset from the Dashboard → Saved Tanks page. The tank modal in the planner then offers a Load from saved tanks dropdown for one-click reuse.
Gas mix fields
When adding or editing a tank, you set the gas mix using two fields:
- O2 %: Oxygen fraction. Set to 21 for air, 32 for EAN32, 50 for deco 50, 100 for pure O2, etc.
- He %: Helium fraction. Leave at 0 for air or nitrox. Set higher for trimix (e.g., 35% He for a 18/35 trimix). The balance is automatically calculated as nitrogen.
Bottom gas vs. deco gas
Each tank must be designated as either a bottom gas or a deco gas:
- Bottom gas is breathed during the descent and bottom phase of the dive. In a single-level plan, this is the gas used at your target depth. In a multi-level plan, you can assign different bottom gases to different levels.
- Deco gas is used during the ascent and decompression stops. The planner automatically switches to deco gas during ascent when the current depth reaches the gas's Maximum Operating Depth (MOD), based on your PPO2 settings.
- Travel gas (optional) is breathed only during descent, before the bottom gas becomes safe to breathe. See Travel gases below.
Travel gases
When your bottom gas is hypoxic (typically trimix with less than 18% O2), it isn't safe to breathe at the surface — the partial pressure of O2 is too low. A travel gas solves this: you breathe it from the surface down to a depth where the bottom gas becomes usable, then switch.
To designate a tank as a travel gas, enable the Travel gas toggle in the tank modal. You can flag a tank as travel gas alone (descent-only), or combine it with the bottom-gas or deco-gas role — for example, EAN32 is often used as both travel gas (on the way down) and deco gas (on the way up).
Switch mode
For each travel gas, the planner offers two switch strategies:
- Automatic (earliest safe depth) — the planner switches from the travel gas to the bottom gas as soon as the bottom gas becomes safe to breathe (i.e., when the depth reaches the bottom gas's minimum depth, based on its hypoxic threshold). This is the recommended default.
- Manual — you specify the exact switch depth. Useful when you have a specific plan (e.g., switch at 30 m regardless of the theoretical minimum).
How it appears in the plan
Once a travel gas is configured, the dive profile shows a distinct descent segment on the travel gas, followed by the switch to the bottom gas at the computed (or manual) depth. Gas consumption is broken down per cylinder in the plan summary, so you can see exactly how much travel gas was used before the switch.
Travel gases are only useful for hypoxic bottom mixes. For standard air, nitrox, or normoxic trimix (≥ 18% O2), no travel gas is needed — the bottom gas is already safe to breathe from the surface.
Loading saved tanks
If you have saved tank presets on your Dashboard, you can load them directly into the planner instead of configuring each tank from scratch. Click the Load Saved Tank button to browse your presets and add them to the current plan.
Gas switching during ascent
When one or more deco gases are configured, the planner handles gas switches automatically during the ascent phase:
- The planner calculates the MOD for each deco gas based on its O2% and your deco PPO2 limit.
- During the computed ascent, when the diver reaches a depth at or above the MOD of a deco gas, the planner schedules a gas switch.
- The gas switch strategy (switch exactly at MOD vs. switch at the next deco stop) is controlled by your Diver Profile settings.
- Gas switch time is also configurable in the diver profile.
The planner validates the Maximum Operating Depth for every gas in your plan. If your planned depth exceeds the MOD of an assigned bottom gas, you will see a warning. Always verify that your gas mixes are appropriate for your planned depth range.
Tips
- Start with a single bottom gas for simple recreational dives. Add deco gases only when planning decompression dives.
- For trimix dives, ensure your helium percentage is set correctly; the planner uses it for both narcotic depth (END) and decompression calculations.
- Use the saved tanks feature to avoid re-entering your usual configurations for every new plan.