Comparison
JJ-CCR or Halcyon Symbios: which one suits you?
JJ-CCR vs Halcyon Symbios: back or chest, weight, electronics, sensors, scrubber, cylinders, bailout, training and price. Compared by someone who dives both.
- JJ-CCR
- Back · 34 kg dive-ready
- Symbios
- Chest · 11 kg dive-ready
- Both
- 100 m · 3 sensors
- Author dives
- Both
I have dived a JJ-CCR for years, in standard and in Joey configuration, and since 2026 two Halcyon Symbios units. So this is not a comparison of two brochures. It is what you notice when you dive one on Saturday and the other on Sunday. First the facts from the manuals, then the experience, then who should choose which.
In short
The JJ is a back-mounted unit: an aluminium housing with two three-litre cylinders inside, a Shearwater controller and a counterlung over the shoulders. Heavy, solid, with the best work of breathing I know. The Symbios is a chest-mounted unit: eleven kilos dive-ready, Halcyon's own electronics, only an oxygen cylinder on board, diluent from your own back gas. Both are rated to a hundred metres and both use three oxygen sensors.
JJ-CCR vs Halcyon Symbios: the specifications
| JJ-CCR | Halcyon Symbios | |
|---|---|---|
| Position | Back, aluminium housing with stand and handle | Chest, on the harness, modular |
| Weight dive-ready | 34.2 kg with two 3-litre cylinders | 11 kg with sorb and a 1-litre cylinder; 12 kg on my scales with a 1.5-litre aluminium |
| Weight without cylinders and sorb | 19.8 kg | 6.6 kg |
| Dimensions | 70 × 40 × 26 cm | 40 × 30 × 12 cm |
| Electronics | Shearwater DiveCAN controller (Petrel) plus separate DiveCAN HUD | Halcyon controller in the head, wireless to handset and HUD |
| Batteries | Two lithium cells for controller and HUD, two 9 V batteries for the solenoid; controller about 90 dive hours | Two rechargeable Li-ion cells, about 40 hours |
| Oxygen sensors | Three galvanic cells, replaced yearly | Two galvanic cells plus one GreenFlash solid-state, up to five years |
| Scrubber | Axial, 2.5 kg Sofnolime, 180 minutes; optional radial 3.05 kg | Axial, 2.35 kg Sofnolime, 160 minutes |
| Cylinders on board | Oxygen and diluent, 3 litres steel each | Oxygen only, 0.8 to 2.5 litres. Diluent from an external cylinder |
| Counterlungs | Over the shoulders, 8 litres | Against the chest, asymmetric |
| Mouthpiece | DSV with ADV; BOV optional | ADV and BOV combined, inside the unit |
| Setpoints | 0.4 to 1.5 bar, low and high | 0.5 to 1.4 bar, low, high and automatic |
| Rating | Tested to EN 14143; 40 m air, 100 m trimix | EN 14143:2013 to 100 m; 40 m on air |
| Price, September 2026 | €10,145 complete with cylinders, wing, backplate, controller and HUD (Germany) | €9,520 with handset without cylinder; €11,116 with handset, HUD, tank pod and cylinder (Germany) |
| Training agencies | Nearly all, for years | GUE, IANTD, PADI, SNSI, SSI and TDI since 2025 and 2026 |
Weight and position
This is the difference you feel every diving day. A JJ with cylinders is thirty-four kilos on your back before you have clipped on a bailout. The Symbios is eleven. That matters beyond lifting: you unclip the Symbios underwater when you need your drysuit, and you shift it aside in a tight restriction, like a sidemount cylinder.
The flip side is a crowded chest. If you dive with a twinset, two stages and a scooter, a lot already hangs there. Online that is the most common objection, and it is fair if those are your dives. I film, and for me the free back is the argument: the camera does not hang off a back-mounted unit.
Breathing
The JJ in standard configuration breathes better than anything I know, in every position. The Symbios breathes remarkably easily, so easily that I have set it slightly harder on every dive with the knob provided for that. The difference is in trim: on the Symbios the unit has to stay at lung level, otherwise the ADV gives too much gas. You learn that on the second dive.
Electronics and sensors
The JJ runs on Shearwater, a brand you never have to think about. The Symbios has Halcyon's own electronics, with the controller in the unit and wireless displays. That wireless link drops for a second now and then; because the controller is in the head, nothing happens when it does. Settings are made in the app and sent to the unit, which is faster than two buttons on a Petrel.
On sensors the Symbios wins on paper: one of the three is a GreenFlash that lasts up to five years. The JJ replaces three cells every year. What the Symbios adds is a separate calibration cap you can forget, and a sensor that will not calibrate in sunlight.
Cylinders and gas
The JJ carries its own oxygen and diluent, two three-litre cylinders. The Symbios carries only oxygen; the diluent comes from your back gas. That is exactly why it is so light, and why you can use it on your existing rig straight away: single cylinder, twinset or sidemount. Adding off-board oxygen is standard on the JJ; on the Symbios you need anexternal MAV.
Bailout
On the JJ a bailout valve is an option you buy, and it makes the mouthpiece bigger. On the Symbios it is inside the unit. The mouthpiece is small, and switching over turns the unit on immediately. On long dives that is the difference in your jaw.
Price
Nearly equal. A complete JJ with cylinders, wing and backplate costs €10,145 in Germany; a Symbios with handset, HUD, tank pod and cylinder €11,116, with just a handset €9,699. The JJ has the reputation of holding its value better than any other rebreather, because it has been around so long. For the Symbios that cannot be said yet.
Training
On the JJ you can train with almost any agency, and have been able to for years. The Symbios has been approved by GUE, IANTD, PADI, SNSI, SSI and TDI since 2025 and 2026, and the number of instructors is growing. In the Netherlands I teachSSI courses on the Symbios. If you already hold a JJ certification, the switch is a crossover, not a new course.
Who should choose which
- Choose the JJ if you do deep, long dives with a twinset, stages and a scooter, if you want the best-breathing rebreather, and if resale value matters to you.
- Choose the Symbios if you are starting with rebreathers and want to keep your existing cylinders, if you travel, if you dive sidemount, or if like me you carry a camera on your back and want a unit you can see and feel.
- If you are undecided, the answer is a try dive. Breathing tells you more than a table.
What others say
From ScubaBoard and InDepth, because my judgment is not the only one. An experienced back-mount diver: "By far the best-breathing rebreather I have dived in all orientations is the JJ-CCR in factory configuration with standard back mounted counterlungs." Another on the Symbios: "too much clutter on the chest with an already relatively complex config with D12 and stages", and "in the end it's just a rebreather in a different location." InDepth on the other side: "A chestmount configuration can also be beneficial for those divers starting their journey into rebreathers, since they can retain their existing cylinder configuration and simply clip the rebreather onto their chest." All three are right. It depends on your dives.