What kind of BCD should you use?

I remember the first BCD (Buoyancy Control Device) Jacket I used and it took me a while to get used to it.

It was a Scubapro BPI BCD. My Instructor at the time (who went by the nickname of Yoda), took me through a few techniques to get more comfortable with it.  Whilst that helped tremendously, I still thought “there has to be more convenient or better designs BCD designs other than holding the inflation/deflation hose up to control buoyancy (the traditional BCD’s).”

Let me rephrase that, there has to be a BCD design that ‘I am more comfortable using.’ 

Just so we are clear, when I talk about the type of BCD “I am more comfortable using”,  I am referring to the inflation/deflation style.  This is what led to me exploring what is out was out there in the market.  That’s the inspiration behind this “pay it forward post”.

There are several types of BCD’s out there that I have tried and let’s be honest, even if you are an Advanced PADI diver, the likelihood is that you’ve probably only used the Traditional style BCD known as BPI (Balanced Power Inflator).  You probably don’t have your own kit either unless you are heavily invested in scuba diving.  So what kind of inflation style BCD’s are available?

Most scuba divers will be familiar with the traditional over the left shoulder inflation/deflation hose styled BCD’s. But joining the race the BCD technology dominance are the Balance Power Inflators (BPI) as seen on Scubapro BCD’s and the i3 technology as developed by Aqualung.

What BCD’s did I try out?  We’ll start of by explaining what they were and what was my experience and hopefully it’ll be of use to any diver out there who has not shopped around, tried many BCD’s or is simply not that experienced yet.

Air Trim

MARES Airtrim System

MARES Airtrim System

Mares pioneered Air Trim systems.  From the Mares site they state: “The first and only pneumatic system (patented) that revolutionizes and simplifies buoyancy control during the dive, making it easy to use, precise and immediate in any position and under any condition. Always at hand, Air Trim simultaneously operates two pneumatic exhaust valves which include a check valve to prevent water entry.”

Air Trim – my experience

In short it simplifies how you as a diver can achieve optimal buoyancy.  The buttons are huge, but really easy to use and they are in your natural hand position. Remember a good diver should not need to swim with their hands!

There also is no corrugated hose so it’s more hydrodynamic.  I found this very easy to use, the buttons were in the right place, the top button inflates, the bottom on deflates.  No nonsense, does exactly what it says.  I however found that buoyancy was a bit of a stickler to achieve in the beginning and found myself automatically changing to a semi to vertical position, when of course you do not need to.  You can change your buoyancy from practically any position with the Air Trim system.

However I did find the BCD to be somewhat bulky for me so my search continued.


Scubapro Equator BCD with BPI technology

Scubapro Equator BCD with BPI technology

To my knowledge Scubapro are the biggest company who really push this technology. You’ll find it on almost all their BCDs. Other companies such as Hollis, Oceanic, Apeks, Aqualung and Cressi also have this technology on their BCD’s. This basically consists of a hose that has two big buttons at the end of it that inflate/deflate the BCD and a capacity to manually inflate the BCD. The general rule is that you should be in a vertical position to achieve optimal buoyancy.

The Scubapro BPI (Balanced Power Inflator) offers the following benefit. “High inflation speed, especially at depth. Divers can achieve very accurate buoyancy control with this technology and it’s been tried and tested for a very long time so it’s very safe. It can be used even when wearing thick gloves.  Its design also allows a diver in extreme cases to breathe air from the BC and exhale in the water”

BPI – my experience

As I mentioned this was the inflation BCD style I learned to dive in.  In fact anyone who learns to dive and qualifies will use a BCD with this kind of inflation technology, regardless of whether the BCD is made by Scubapro, Mares, Cressi or others.

This is a very simple BCD to use in all honesty and I would probably buy one as a back up to my current BCD I if I could. Scuba equipment is not cheap! There are much fewer moving parts on here so there isn’t much that can go wrong. That’s how I used to think and still do in part.  The simpler you keep your diving the better the experience.  For example, if you are a technical diver then you’ll dive with just what you need.  Many technical divers I know can end up carrying a fair amount of kit on a dive and dive with almost all of it, but only carry the essentials.  I knew a guy who always wanted to dive with a small emergency tank or air, but the dives he did really didn’t call for it.  However he never equipped himself with an alternate second stage.

Logic clearly didn’t prevail.  Go figure.

Anyway, would I still use this type of BCD, yes.  Is it my first choice, no.


Aqualung Pro QD i3

Aqualung Pro QD i3

Aqualung added to their The Aqualung i3 technology is simple and intuitive. Move the lever up to go up; down to go down. Unlike a traditional inflator at the end of a floppy hose, the i3 never moves. It is stationary at the same place where your left hand normally rests. It is always in the right place at the right time. The i3 does not use pneumatics or hydraulics to activate the Flat E-Valves. That means, it will not fail nor will there be any leakage. Using push-rod technology, the kind found in aircraft, the design remains simple and robust.

i3 – my experience

I admit I bought this before actually trying it.  Why? My previous use of the Air Trim system by Mares was very positive, but that BCD I personally felt was a bit bulky.  This BCD by Aqualung for me were very streamline.  My buoyancy control was very precise.  I found that I could very quickly get optimal buoyancy as soon as I descended without touching the bottom of the ocean. On many dives I’ve simply descended and start swimming straight away with no problems.

I’ve had this BCD for 4 years now.  It receives its standard service and continues to work just like I first bought it.


I don’t think it’s as simple as saying which one is better, I believe it more so comes down to which one you find more comfortable using.  Scuba diving is a sport (or hobbie to many) that can be extremely fulfilling, fun and enlightening.  You can meet some great people and see the world if you are a warm weather diver. But it can be dangerous as well especially if you do not know what you are doing or are unfamiliar or are uncomfortable with the equipment you use.

Let’s face it, when you first learn to dive, mastering buoyancy control is one of the most difficult skills to learn.  So the more comfortable you are the better.  If you rent your BCD’s when you dive the likelihood is that you’ll always use a BPI BCD.  If you are thinking of buying a BCD or getting a new one, then hopefully my experiences and the information above will help.

Keep diving, stay safe.

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