Regulator Basics

If we had gills, breathing underwater would be easy. But since we don’t, we rely on the services of a regulator.

Years ago, there weren’t too many choices. Today, you’ve got more choices and better overall quality.

And since a ‘reg is one of the three ‘high value’ items that divers buy, you are very likely to do your research on what’s the best option for your type of diving and your budget.

Where will you be diving?

Some regulators are designed for cold water use, others are light weight warm water regulators best suited for diving overseas when luggage weight is an issue.

When purchasing a regulator, you really need to think about where you will be diving and the type of diving you will be doing.

What is your budget?

How much can you afford to spend? There’s no sense in getting excited about a £1000 regulator when your budget only allows £500.

But sometimes, spending only £50 more than you’d planned may get you a significantly better regulator.

How do I know how it breathes?

How easily a regulator breathes is probably the single most important factor for most divers.

At Aquanaut we we are happy to set a regulator up on a tank so you can feel how it breathes on the surface. Performance may of course change slightly at 40m! Don’t be thrown if the regulator you’re testing makes a weird honking/buzzing/vibrating noise.

When you test a reg in air, the diaphragm in the second stage will sometimes vibrate producing the sound. This doesn’t happen when you’re underwater. Some people take a huge breathe of air and pronounce, “This breathes really good.” Inhale hard enough, and you can make a straw seem easy-breathing!

The trick is to inhale as gently as possible. Don’t count the first inhale or exhale. Regs that have been dry (even for just a day) may “stick” at first. Take a breath or two to loosen the reg up, then see what you think.

Fit and Comfort

How does the reg fit in your mouth?

Does the exhaust tee hit you in the chin?

Don’t buy a specific regulator just because you like the mouthpiece. Don’t avoid buying another one because you didn’t like the mouthpiece.

Although mouthpiece fit and comfort is very important, mouthpieces are interchangeable from brand to brand

Balanced vs. Unbalanced

In simple terms, a balanced regulator breathes pretty much the same at all tank pressures – whether you are diving shallow or deep, a full tank or near empty tank. An unbalanced reg will start to breath more stiffly as the tank pressure drops, especially as the tank pressure nears the intermediate pressure of the first stage.

A balanced reg will cost a bit more, but will breathe more evenly over the course of a dive. However, if you’re not watching your gauges, you may get very little inhalation warning that you’re about to suck your tank dry.

An unbalanced reg should be a little cheaper, but will start to pull harder towards the end of the tank. Some divers like the fact that the reg is, in effect, telling you you’re running low on air.

Piston vs. Diaphragm

This refers to how the first stage (attached to the tank) reduces tank pressure (upwards of 232 bar) to an intermediate pressure (9 – 10 bar), so the second stage (the part that’s in your mouth) can reduce the air to ambient (surrounding) pressure.

Regs with diaphragms in the first stage should be a bit less expensive but also cannot be as finely tuned, although they’ll perform well.

Regs with pistons will cost a bit more but are generally higher-performance because they can be more finely adjusted. However, when it comes time for the annual service, piston regs may cost you a bit more.

Adjusting the Airflow

Some regs come with a knob that can adjust the inhalation pressure, and/or a separate lever to adjust the flow of the air once it’s started.

You’ll pay a little more for these features but they’ll allow you to adjust the reg to meet diving conditions, as well as being able to “tighten down” the reg if it starts a slight free-flow.


Look at the number of high-pressure and low-pressure ports on the first stage and make sure there’s enough for your needs.

All regs have at least one high-pressure port (for your pressure gauge) and many have two, allowing you to run an extra pressure gauge or air-integrated computer.

If you are diving in a dry suit, you will require at least 4 low pressure ports.

Ultimately there are a LOT of regulators around in the market today. The best advice is to come into the dive centre and talk about your requirements, touch and feel the equipment before you decide what is best for you.