OX500Plus mini scuba tank: one half-liter tank, two ways to wear it

The OX500Plus starts from the same 0.5 liter tank as the OX500: same volume, same 200 bar, same air time. What changes is everything around it. It comes with a harness, an external regulator on a hose and an external pressure gauge, so you can wear the tank on your back instead of holding it in your teeth.

Two ways to use it

In the mouth. Exactly like the OX500: you breathe straight from the tank, which you hold in place with your mouth and a hand. It is the quickest way to go and look at something.

On your back. The harness holds the tank between your shoulder blades and the regulator reaches your mouth on its hose. Both hands are free. The external gauge hangs where you can read it at a glance, so you always know how much air is left without taking anything out of your mouth.

Switching from one mode to the other takes a few minutes on deck.

When hands-free makes the difference

Holding a tank in your teeth is fine for a look. It gets tiring fast when the job needs tools.

• Changing a zinc. One hand for the wrench, one for the new zinc, and the screws to keep track of. On your back, the tank stays out of the way.
• Scraping the running gear. Barnacles on the prop, the shaft and the strut come off with a scraper and some force. You will want to brace yourself with your free hand. See how to clean a boat propeller.
• A rope wound tight around the shaft. Cutting a line that has fused into a hard knot is a two-handed job: one hand holds, the other cuts. Our guide on freeing a rope from the propeller explains the method.
• The mooring. Checking a shackle or a swivel on your own mooring means holding on to the chain while you look.

With the OXAIR mask

Wearing the tank on your back also frees your face for the OXAIR full-face mask. At the surface you breathe through its snorkel; when you dive down for a closer look, the air from the tank takes over through the connector. The mask fits all four OXSEA tanks, and the OX500Plus is the lightest of the back-mounted options.

Air time and refills

Up to 8 minutes near the surface, breathing calmly. Work, cold and stress shorten that. The tank holds roughly 100 liters of air once expanded, about 3.5 cubic feet.

It refills like the OX500, with the hand pump in about 20 minutes or the 12 V / 220 V compressor in about 12. The tank ships empty: fill it before your first dive.

OX500Plus or OX500?

Pick the OX500 if your jobs are quick checks, a look at the prop or the anchor, and you like having the simplest possible kit on board.

Pick the OX500Plus if you expect to use tools, want to wear the tank on your back, or plan to snorkel with the OXAIR mask. If you find that 8 minutes is not enough for your jobs, the OX1000 doubles the air and is worn the same way.

Before you go under

The same rules apply whether the tank is in your mouth or on your back: breathe continuously, never hold your breath on the way up, ascend slowly. Engine off and keys out before anyone goes under the boat, and a dive flag up: see our guide to dive flag rules in the US and the safety guide on oxsea.shop.