Like many scuba divers I used rented equipment that dive operators provided. Usually you get well-maintained basic equipment. If you commit to scuba diving, however, buying your own gear becomes desirable.
One of the first things to buy is a regulator. I found it very difficult to choose one brand or model over another. That's because there are few comprehensive reviews on the web, and little agreement in the community about what's best. I hope this article makes it easier for you to make a decision.
So, which regulator should you buy?
Short answer: It doesn't really matter. Scuba regulators are a mature technology with little variation in quality. Equipment failure is not a relevant cause of accidents compared to human error (including ignoring equipment maintenance recommendations). Any complete regulator set around 300-400 Euro will keep you safe and work well if properly maintained. So just go ahead and buy a set from one of the major brands (in Europe: Aqualung/Apeks, Scubapro/Subgear, Atomic Aquatics, Mares and others).
Long answer: It depends on what you need it for, and personal preference. I think the following criteria can be used to compare regulators and make an informed decision.
1. Total cost of ownership
Regulators need to be serviced regularly to make sure that salt water and other influences don't put you in danger. To my knowledge, some manufacturers recommend either one or two year intervals (or a certain number of dives, whatever comes first). These are often mandatory to stay under warranty. Service cost is around 100 Euro depending on the brand. As you can see, suddenly a one or two year interval can make a big difference. In order to compare regulators based on price, ask the shop that would most likely service your gear for maintenance prices and calculate the total cost of ownership for 5-10 years.
2. First stage design
There are three designs for the first stage (which attaches to the tank and reduces the air pressure).
Diaphragm. Preferred by divers in cold or dirty water (sediment, oil etc.) because of its sealed construction.
Air-balanced piston. Preferred by divers that value maximum air delivery and a simpler construction. Here water enters the first stage.
Downstream piston. Simple construction type that you should only buy if price and easy servicing count the most.
3. Second stage characteristics
While the first stage does all the work, the second stage is responsible for much of the subjective feel of breathing under water. They differ mostly by whether you can adjust how much you have to suck to start the air flow (cracking pressure adjustment; knob on the side) and whether you can control how easily air flows once it has started to flow (Venturi adjustment; lever on the side; sometimes automatically controlled without a lever). These features often carry different names to confuse you. Don't let them.
4. Availability of support
In general, important things are best discussed with an experienced person. A major consideration of which regulator you should buy is which brands and models your local dive shop or school offers, likes, and services reliably. If in doubt, go with the recommendation from an expert you trust. I also tried to consider with which brand I would easily find help abroad. I heard some conflicting information, and decided that any established brand should be fine.
Things that manufacturers want you to think are important but about which I'm not so sure
- Innovative breathing system X. Many manufacturers have come up with nice names for minor changes in their regulator design. Looking at the current market, there's nothing I can see that sticks out.
- Materials. These determine cold water performance (metal or plastic) and durability against corrosion (titanium, stainless steel, or plated brass). If you dive in very cold water, you need more metal. If you want to service your regulator less often, you need titanium or stainless steel. However, I think that if you follow suggested maintenance intervals, it doesn't matter so much.
- Weight. Unless you use titanium elements, the weight won't differ that much between regulators. Not sure if the weight difference under water is worth the price difference.
- Vents. There will be bubbles, and a newly designed vent will not change that.
- Nitrox compatibility. Almost any regulator can handle up to 40% oxygen. If you want more, you need a special regulator.
- Swivel. Maximizes comfort of the second stage, but is also seen as an unnessecary point of failure by some. If your hose configuration is correct, you shouldn't need a swivel.
- Tank fitting. If you dive internationally, get a DIN connector with a yoke (INT) adapter.
Caveat: I'm by no means professional or experienced (at the time of writing). Regulators are life support devices. My goal is to provide helpful criteria regarding a purchase. Don't be stupid; go talk to a experienced professional before you make a decision.