OX500Plus mini scuba tank: the half-litre tank you can wear on your back

Take the OX500, keep the half-litre tank and the 200 bar, then add a harness, an external regulator on a hose and an external pressure gauge. That is the OX500Plus. The air time does not change. What changes is that your hands are free.

Two ways to wear it

• In the mouth, exactly like the OX500. Quickest for a look at the prop or the anchor.
• On your back, with the harness. The regulator comes over your shoulder on its hose and the external gauge hangs where you can read it in a glance.

You can switch from one setup to the other in a few minutes, on the deck or on the beach.

Why hands-free changes the job

A tank held in your teeth is fine while you look. It becomes hard work as soon as you need tools.

• Anodes. Undoing the old anode, holding the new one, starting the screws without dropping them: that is three hands' worth of work already. With the tank on your back you have two.
• Prop and leg. Barnacles and tubeworm on an outboard leg or a shaft come off with a scraper and some leverage. You will want one hand on the boat. See how to clean a boat propeller.
• A line fused round the shaft. Holding the line taut with one hand and cutting with the other is the only way to do it cleanly.
• The mooring. A quick look at the top of your swing mooring means holding on to the chain while you check a shackle. Our swing mooring guide explains what NSW and Queensland require and what you can see yourself.

Snorkelling with the OXAIR mask

On your back, the OX500Plus leaves your face free for the OXAIR full-face mask. You snorkel at the surface, and when you dive down for a closer look, the tank takes over through the connector. On the Ningaloo or Great Barrier Reef, at Rottnest or in Cabbage Tree Bay, it means staying down to watch instead of coming up after one breath hold. Before you go, check the zone rules in our guides to marine park zones, Perth and Rottnest and Sydney shore spots.

The mask fits all four OXSEA tanks. The OX500Plus is simply the lightest of the ones you wear on your back.

Air and refills

Up to 8 minutes near the surface, breathing calmly, from roughly 100 litres of air once expanded. Effort, cold and nerves shorten it.

Refilling is the same as the OX500: about 20 minutes with the hand pump, about 12 with the 12 V / 220 V compressor. The tank ships empty.

OX500Plus, OX500 or OX1000?

• OX500 if your jobs are quick looks and you want the simplest kit in the hatch.
• OX500Plus if you will use tools, want the tank on your back, or plan to snorkel with the OXAIR mask.
• OX1000 if 8 minutes keeps falling short. It is worn the same way, with twice the air.

The rules stay the same

Breathe continuously, never hold your breath on the way up, ascend slowly. Engine off before anyone goes in, and the Code Flag A up: see our dive flag guide. From K'gari north, in the Top End and down the WA coast to Exmouth, wear a stinger suit, above all from November to May: our stinger season guide explains why. And remember that a mini tank counts as breathing apparatus under fishing rules: what each state allows.