CCR Instruction for the Dive Rite O2ptima, Mares rEvo and Poseidon Se7en+ rebreathers.

Dive Gear Express offers instruction at our facility in SE Florida for all models we sell. Below is general information on rebreathers, transitioning to closed circuit diving, and rebreather safety. Experienced rebreather divers seeking advanced training can skip to course descriptions, prices, and logistics, plus an equipment list for rebreather training.


Mark Derrick, a long time technical diving instructor on staff at Dive Gear Express, is the author of much of the content on this page and the opinions expressed here are solely his own. A certified SCUBA diver since the early 70's, Mark is originally from North Alabama. Earning his first rebreather instructor rating in the late 90's, in 2000 he retired from the information technology sector, moved to Florida and focused on diving and technical instructing. Mark eventually ceased all his open circuit diving to focus exclusively on closed circuit rebreather diving. While he is an active rebreather technical diver, choosing to dive closed circuit exclusively Mark has not performed an open circuit dive since 2005. Now based in Pompano Beach Florida, Mark is an sport and technical CCR diver and CCR diving instructor for several different brand and model rebreathers.

Rebreather Diver

Some Rebreather Vocabulary

A SCUBA device that allows you to recycle what you breathe over and over again is called a rebreather. Your body burns the oxygen you inhale then you exhale the carbon dioxide waste, so a rebreather does the following:

  • Captures and recirculates the gas you are breathing with a breathing loop.
  • Purifies the gas to remove carbon dioxide with a process called scrubbing.
  • Refreshes the breathing gas by adding replacement oxygen gas.
  • Compensates for reducing loop volume during descent by adding inert diluent gas.

There are a variety of designs for rebreathers and their components. For recreational diving the most versatile and popular type of rebreather is the fully closed-circuit breathing loop and is often referred to as a CCR. The loop uses counterlungs to store the gas when you exhale and to supply the gas when you inhale. Also part of the loop is a scrubber canister, which contains chemicals to act as a carbon dioxide absorbent. As the oxygen in the loop is consumed by the diver, the CCR replaces it to maintain a constant level of oxygen known as the PO2 set point.

The rebreather set point can be controlled using either manual or automatic systems, or a combination of both. There are lower cost manual only rebreathers (mCCR) where the diver is responsible for monitoring the breathing loop via oxygen sensors and operating a valve to manually adjust the oxygen level. The most popular closed-circuit rebreather design today is capable of automatic electronic (eCCR) operation. The eCCR uses a small battery powered computer to continuously monitor the oxygen sensors and automatically control a solenoid valve to adjust the amount of oxygen. (Both the Dive Rite O2ptima and Poseidon Se7en rebreathers are eCCR types.) Hybrid design closed-circuit rebreathers (hCCR) include a simple passive orifice to continuously flow oxygen in to the loop at a low rate near resting metabolic consumption and use the oxygen solenoid to actively add more oxygen to achieve the PPO2 set point. (The Mares rEVO rebreathers are usually configured as an hCCR.)

Deciding to Switch to Closed Circuit

CCR is a reasonable choice for any active diver who is looking at CCR as a new learning opportunity and personal accomplishment. If you are early in your project of researching the idea of diving with a rebreather, you could start by reading Basics of Rebreather Diving by Jill Heinerth. In reality, the information you need to make a decision is pretty straightforward.

Key Advantages of Rebreathers

  • Silence - The closed-circuit rebreather produces almost no bubbles and the resulting silence enhances the dive in part because the marine life are not alarmed by the diver. If you are a photographer, the silence of the CCR will make huge improvement in your marine life interactions and photo opportunities.
  • Extended Ranges for Depth and Time - The CCR carries hours of breathing gas regardless of depth, so diving time is no longer limited by the size of the tank. A rebreather can also greatly extend the no decompression time limits (NDL's) for sport divers. If you are a technical diver or overhead environment diver, then almost certainly a CCR makes sense.

Key Disadvantages

  • High Cost - There is a wide price range, but the cost to become an eCCR diver is typically many times that of an open-circuit diver. Consumables in remote destinations can also be costly to obtain.
  • Complexity - The rebreather being more complex means additional time spent on logistics and equipment maintenance. Rebreather divers must always plan ahead to assure availability of absorbent and oxygen.

Another way of analyzing the CCR decision is to ask yourself "Am I able to do the dives I want on open-circuit?" If the answer is "No" because your diving has reached a limitation that a rebreather could overcome, then it is time to consider becoming a closed-circuit rebreather diver.

Are Rebreathers Safe?

At Rebreather Forum 3 held in 2012, statistics were presented which suggest closed-circuit rebreather diving is five to ten times higher risk than open circuit scuba. Some of the statistical increase may be due to rebreathers enabling divers to attempt extreme dive profiles which are themselves inherently higher risk than dive profiles attempted on open circuit. Many experts were of the opinion a lack of experience, along with inadequate and poor quality training, was a widespread problem in the rebreather community.

Subsequently, The Rebreather Education & Safety Association was formed. RESA is not a training agency; RESA is a consortium of rebreather manufacturers, dive training agencies, and knowledgeable individuals who have established recommendations for a student to learn how to properly use their rebreather. RESA guidelines were published in 2018 to help address findings of inadequate training and rapid progression of training that are too often apparent in dive accidents. All major training agencies have updated their training standards and policies to align with the RESA guidelines. While it's too early to correlate the effect of these changes, recently there does appear to be a significant reduction in rebreather related fatalities.

No rebreather is foolproof, and the fact remains that compared to open circuit there is a disproportionate number of rebreather fatalities, many of which have ultimately been attributed to diver error. Your safety while diving is controlled by you, not by your rebreather.

What Rebreather Should I Buy?

All of the major rebreather models are good quality units. There is no perfect rebreather; they all have strengths and weaknesses that make each uniquely more or less suited to your needs. Beyond the features of the rebreather itself, you should consider model design goals and quality of support. Keep in mind when talking to CCR divers and even CCR instructors, you can hear some strongly biased opinions regarding specific rebreathers and what might be right for them may not be appropriate for you.

In addition to the Dive Rite O2ptima (Shearwater electronics), Mares rEvo (rEvodream + Shearwater electronics), and Poseidon Se7en+ (G7 electronics + M28), there are other good eCCR choices with the Innerspace Megalodon (Shearwater electronics), and AP Diving Inspiration (Vision2020 electronics). Divers on a tight budget might consider the mCCR designs from KISS. North American and Caribbean based divers new to rebreathers would do well to select from this "short-list" for first time buyers, although there are many other choices and this list should not be construed as a recommendation or disparagement of any specific unit.

The O2ptima, rEvo and Se7en+ rebreathers are richly featured and proven designs with good redundancy from well established manufacturers. The O2ptima is a North American design that favors the technical diver already doing physical overhead or planned decompression dives. The Se7en+ is a European design that favors the sport diver with intentions of continuing on to technical diving, and offers a unique automated checklist power-on self test. The rEVO is a hybrid type from Europe with an inherent backmount counterlung design that offers a unique dual scrubber that is exceptionally efficient in the use of absorbent. All three units are robust CCR choices for recreational sport diving.

If you are uncertain about your selection, a carefully supervised confined-water 'rebreather experience' might help with narrowing your choice and Dive Gear Express is happy to organize a private pool trial. However, please keep in mind these experiences are of limited value because closed-circuit diving has little in common with open-circuit diving. Imagine entering the water knowing nothing about open-circuit diving with no buoyancy control skills in an effort to select the "best" open-circuit equipment for your needs. Like automobiles, once you have selected a specific rebreather there are still several configuration options to determine the final unit to be delivered. Our experienced rebreather staff at Dive Gear Express stand ready to advise you on the various options, but Mark's detailed O2ptima FAQ, Se7en+ FAQ, and rEvo FAQ will answer many of your questions about the specific models we sell.

Perhaps the most important decision you will make is not the brand or configuration of your rebreather, instead the most critical decision you will make is choosing your instructor.

Closed-Circuit Rebreather Training Course Summaries and Prices

Rebreather training at Dive Gear Express is conducted to meet training agency specific standards, and the general guidelines of RESA. We offer a rebreather training course progression with multiple entry points and each program with different prerequisites, information, skills, dive exposures and limits; as taught at Dive Gear Express the programs are:

  • Sport CCR Diver - Air -- This program is the entry point for open-circuit divers who expect to remain well within sport diving limits. Divers learn to plan and conduct no-stop required CCR dives to a maximum depth of {100fsw | 30msw} using air diluent. The training time is approximately five days including open water training dives. Price for instruction and training materials is $1500.00; price does not include CCR consumables, equipment rentals or boat trips.
  • Sport CCR Diver - Mixed Gas -- This program is the recommended entry point for experienced open-circuit sport divers. Divers learn to plan and conduct no-stop required CCR dives to a maximum depth of {130fsw | 40msw}. We generally recommend this Mixed Gas version and teach rebreather divers to substitute normoxic trimix diluent (21% oxygen, 35% helium) rather than air even within recreational sport limits for the benefits of reduced narcosis, better work of breathing, and improved scrubber function. The emphasis in this program is on managing the rebreather and should an issue develop then safely ending the dive on open-circuit bailout. The training time is approximately six days including open water training dives. Price for instruction and training materials is $2000.00; price does not include CCR consumables, equipment rentals or boat trips.
  • Decompression CCR Diver - 45M -- This skills intensive program is the recommended entry point for open-circuit divers already certified to perform required-stop decompression dives -OR- experienced open-circuit sport divers with Sport CCR certification who have logged a minimum of 20 dives and 20 hours on their specific unit. Available in an Air version, we prefer the Mixed Gas version and teach divers to plan and conduct required-stop decompression CCR dives to a maximum depth of {150fsw | 45msw} using normoxic Trimix diluent and a single off-board bailout cylinder. The emphasis in this program is on diagnosing and resolving in-water issues in order to remain on the rebreather loop whenever possible. The training time is approximately seven days including open water training dives. Two of the training dives will be deeper than {110fsw | 35msw} with a planned decompression obligation. Price for instruction and training materials is $2500.00; price does not include CCR consumables, equipment rentals or boat trips. This program content is sometimes referred to as "Mod 1 CCR".
  • Decompression CCR Diver - 60M (optionally 70M) -- This program offers training to qualify the Decompression CCR Diver - 45M to independently plan and conduct multi-stop decompression dives to a maximum depth of {200fsw | 60msw} using Trimix diluent along with two bailout cylinders and gases. The diver also must have logged a minimum of 50 CCR dives and 50 CCR hours that includes at least 25 dives and 25 hours on the specific unit, at least 30 CCR dives deeper than {90fsw | 27msw}, and at least 10 CCR required-stop decompression dives. The student candidate must complete a series of progressively deeper open water multi-stop decompression training dives. Two of the training dives will be deeper than {100fsw | 30msw} with a planned decompression obligation and two additional training dives will be deeper than {160fsw | 50msw} with a planned decompression obligation. The 70M option includes an additional dive between between {210fsw | 63msw} and {230fsw | 70msw} deep. This program content is sometimes referred to as "Mod 2 CCR" but is tailored to the candidate's prior training and experience; contact us to discuss your specific goals.
  • Decompression CCR Diver - 100M -- This program offers training to qualify the Decompression CCR Diver - 60M to dive to a maximum depth of {330fsw | 100msw} using very hypoxic Trimix gases and three bailout cylinders. The diver also must have logged a minimum of 100 CCR dives and 100 hours on the specific unit, at least 25 CCR multi-stop decompression dives deeper than {132 fsw | 40 msw}. The student candidate must complete a series of progressively deeper open water multi-stop decompression training dives. Two of the training dives will be deeper than {130fsw | 40msw} with a planned decompression obligation and two additional training dives will be deeper than {230fsw | 70msw} with a planned decompression obligation. At this level, the deeper required-stop training dives are typically conducted one per day. This program content is sometimes referred to as "Mod 3 CCR" but is tailored to the candidate's prior training and experience, contact us to discuss your specific goals.
  • CCR Crossover -- These fast paced programs are for the experienced and active CCR Diver who wishes to cross-train for certification on the Dive Rite O2ptima, Poseidon Se7en, or Mares rEvo unit. Semi-closed circuit divers and CCR Divers who have less than 10 logged CCR dives in the last 12 months must take a full CCR course instead of a crossover. This program is tailored to the candidate's prior training and experience, contact us to discuss your specific goals.

Please take a moment to review the RESA Minimum Requirements (December 2018) to discover what to expect from your CCR training. Pre-requisites and content as described above will vary as appropriate to meet specific dive training agency standards, but the programs at Dive Gear Express have similar structure and elements: on-line programmed instruction review completed prior to arrival, facilities orientation, prerequisites and standards review, safety discussion, hands-on detailed assembly and configuration of rebreather, classroom lectures, in-water equipment skills sessions, pre-dive trip briefings, rebreather setups using a checklist, half-day dive boat trips, open water training dives, post-dive trip debriefings, and exit interview. Class sizes at Dive Gear Express are a maximum of four students and CCR instructor; plus an in-water assistant when there are more than two students. We also provide additional education and learning opportunities whenever training agency standards and logistics allow.

As with any SCUBA course, training is purchased but certifications are earned only when the student and instructor are both in agreement the training requirements have been completed to their mutual satisfaction.

Your Rebreather Training at Dive Gear Express

Training is normally done right here at our fully equipped facility in Pompano Beach, Florida USA. The logistics for rebreather diving are extremely good. Our facility has a comfortable classroom, meticulously maintained mixed gas and oxygen fill station, convenient work space for CCR setup and tear-down, extensive stock of consumables and spares, as well as on-staff equipment repair technicians. The water conditions are excellent year round (low 70's in the winter and low 80's in the summer) and the range of dives offer you a nice bit of experience (shallow and deep reef, shallow and deep wreck) to learn on your rebreather. On-site training at your choice of any global location with appropriate logistics is also available; we've organized training aboard yachts and at resort destinations all over the world.

The calendar schedule varies depending on your requirements, but course openings are available most weeks of the year. Keep in mind that finishing on-time assumes we will be able to dive without interruption from logistics or weather. The reality is needing an extra day is not unusual, and we recommend planning for an extra day or two. We typically begin classes at 9AM on a Saturday morning and suggest travelling students plan their departure for Sunday of the following weekend. We find many divers prefer a slower pace, and we are happy to accommodate. If the extra time is not needed then it allows additional diving immediately following course completion to help reinforce your new skills. Send us some date ranges that work for you and we will reply with some specific choices of availability.

Travelling students may wish to stay at the Hilton Doubletree - Hillsboro (4 stars on TripAdvisor) because it is conveniently located. However, there are a wide range of private and chain hotels in the Pompano Beach area, the choice is entirely yours. You also will benefit from having a rental car during your stay or you can use a ride-share service such as Uber or Lyft.

There is a liability and assumption of risk waiver that you must read before class. There is also a form that contains a few questions about your health. If you answer "YES" to any of the questions, depending on the circumstances you may be required to have a doctor's letter that clears you for scuba diving activities. If you are currently a smoker, we require you to refrain from smoking for 24 hours prior to any in-water activities on the rebreather.

In preparation for the course, we ask you to read the following, PRIOR to attending the first day of class:

  • Rebreathers Simplified Revision 4 by Dr. Mel Clark. This text is recommended reading only for divers taking their first rebreather course. Although not a formal requirement of the training standard, this text is very useful in providing us with a common vocabulary, and also offers a great review of basic physics and physiology particularly as it applies to rebreathers. This will save time in the classroom lecture, allowing that time to be spent gaining a deeper understanding of rebreathers. If you do not already have a copy of this manual, you may order it from the Dive Gear Express website.
  • The manufacturer supplied user manual for your specific model rebreather. The primary goal for reading prior to class is that you can identify major sub-assemblies, key components and their functions - especially how to read and interpret the electronics. Don't worry too much about the specifics of the checklists at this point, you will review that content during class. The current version can be downloaded from the website of the manufacturer for your specific model rebreather:

Keep in mind that helping you to understand the material and answer your questions is a key part of the job of your instructor. We look forward to seeing you in class.

Equipment You Will Need for the CCR Diver Course at Dive Gear Express

Obviously, you will need your rebreather with BCD and harness. If you purchased your rebreather from other than Dive Gear Express, most students arrange to ship their rebreather ahead to our offices in Pompano Beach. If you purchased your rebreather used, we recommend that it receive a factory authorized overhaul service prior to the course. Please be aware that training standards prohibit functional modifications to the rebreather unit that are not approved by the manufacturer. Other equipment you will need to bring:

  • You will need a wet or semi-dry neoprene exposure suit, 3mil or 5mil in the summer, 5mil or 7mil in the winter, or you can use a dry suit. A full hood, even if just nylon, and tropical style dive gloves are a good idea and recommended.
  • You will need technical style diving fins with boots . A spring heel strap design is strongly recommended.
  • You will need a low volume dive mask that fits well without having to frequently clear it. A key feature of the mask is that you will need to be able to clearly see the heads up display mounted on your rebreather, this implies that you will need a 'tear drop' style lens with a large look down field of vision.
  • For the courses with planned required-stop decompression, you will need a back up mask.
  • You will need a delayed surface marking buoy (DSMB) along with a safety reel containing ~150 feet of line and a line cutting device.
  • For the courses with planned required-stop decompression, you will need a back up DSMB and spool/reel containing ~75 feet of line.
  • You will need a slate or other writing device. An executive slate or tablet style is best, underwater notepad style works too, but a not wrist slate.
  • For off-board open-circuit bailout, you will need an open-circuit regulator with a 40-inch LP hose plus an SPG with a short HP hose or a button gauge.
  • Courses with planned required-stop decompression require multiple open-circuit regulators suitable for use with oxygen rich decompression gases.
  • For the courses with planned required-stop decompression, you will need a back up depth and time device. A dive computer that offers a constant PO2 mode (aka CCR mode) is recommended. Perhaps best is a redundant decompression and PO2 monitoring package option integrated with your rebreather.
  • Please bring your dive certification cards along with your dive log as well as a photo ID. You will not be able to dive until we can verify your certification and the experience documented in your dive log meet the prerequisites required for training.

Tanks and weights are supplied as needed as part of the course at no charge, or you can bring your own if you prefer. We have CCR oxygen and diluent cylinder pairs of 2L & 3L aluminums and 2L, 3L & 4L steels, all with your choice of inline or modular valves, plus bailout 30's, 40's and 72's rigged for sidemount. If you bring your own cylinders they must have current hydro with annual VIP, be suitable for use with gases containing greater than 23.5% oxygen, and appropriately labeled. Dive Gear Express has a meticulously maintained fill station with a carbon monoxide detector, and can supply banked OCA grade Nitrox 32 and 21, UHP grade Trimix 21/35, ABO grade Oxygen 100, as well as custom gas blends for technical courses. We suggest you have your own gas analyzer, otherwise you can use the fill station analyzers.

You'll also need the usual other non-dive comfort stuff you are in the habit of using in tropical diving... swimsuit, towel, sunblock, sunglasses, etc. In the winter you will want a light jacket with hood or dive parka. If you don't have some item mentioned above, don't worry about it. Other than exposure suits, we have one of the largest inventories of technical dive equipment in Florida.

Ready to dive silent? Contact us and Mark will reply.

Open-Circuit Etiquette with Closed-Circuit Divers

Rebreather Diver on Boat

If you are an open-circuit diver, it is becoming increasingly common to find yourself on a boat with a rebreather diver; or perhaps you may even get assigned a rebreather diver as a buddy. Like you, the rebreather diver has been trained to do a few minutes of setup and checks on their equipment before they dive. Often, another diver will approach and begin asking questions at just this moment. The rebreather diver really would like to talk about their equipment and answer questions, but part of their training included a reminder to avoid becoming distracted during their checks. Help them out by waiting until you see their setup is completed. If you are assigned a rebreather diver as a buddy, they will need to have a brief safety protocol discussion with you as there are some differences from your open-circuit training.