Getting a hyperbaric chamber for advanced sports performance definitely requires different protocols than just laying in the chamber an hour a day. (note: the advanced level is a step down from Master Level. Those using hyperbaric chambers on an advanced level do NOT need a helper to make sure protocols are taken.
Depending on the reason for using the chamber, some people might prefer to put an infrared mat under the chamber. Others are doing EWOT and need to keep the chamber cold so they don't get overheated. If doing EWOT I urge people to not just get a muffler that attaches to the compressor but a reverse pump that takes air out the chamber and cools it and then puts it back in. These cost around 750 dollars and are custom made. If the chamber is at 90 degrees it will bring it back to 70 degrees. This is the only one I know that can lower the chamber temperature 20 degrees.
Also many people who are going in for health reasons might find a vibration under them soothing. It is hard to stay positional tolerant for long times. Putting a vibro accoustical speaker under the plat and a matrix cushion inside the chamber helps get rid of pressure points. I use 2 matrix cushions. I have a waterproof pad on top of the cushion as I sweat a lot if I don't have the cooler on. Sometimes when doing HBOT and using my oxygen concentrator, I want to burn the oxygen by heating my core up. I find that when my core is heated 2 degrees while I am in the chamber from the infrared mat under the chamber, I absorb oxygen much better. Since I don't have access to hard shell chambers every day, if I am going to take an hour jiu jitsu class and I don't have time to do longer sessions, according to my aspirator my blood oxygen levels are always higher when my body was warm in the chamber.
So, there has to be a balance between using the cooler and being really warm and having a hot and muggy chamber. Having dual compressors can help get rid of the mugginess and keep the chamber somewhat cooler but all compressors heat up the air.
Note: some hyperbaric chamber compressors heat up the air more than others. Many people since two compressors in line and plug it up to one air valve while some chambers have 2 air valves and you can use 2 compressors. Some people have 2 compressors in since on each side, totaling 4 compressors. It really just depends on the quality of air people want while in their hyperbaric chamber.
There are other protocols that allow people to self administer unlike the master level where another person is needed to monitor. Note: you can also get a chamber with a power outlet that allows a hole for putting a power cord. Doing this changes the game. With electricity, it is much easier to sleep in chambers and if upgrading a chamber to 10 feet long instead of the standard 7 feet, that 3 extra feet gives space to put everything so it is not cluttered around you. These aren't factory stock lengths so you have to ask for them. Only some companies offer this option.
For help picking out the right chamber for your needs or getting information on different protocols please take my hyperbaric chamber quiz.
High dosage oxygen therapy VS hyperbaric oxygen therapy.
Depth equivalent of 16 feet under water is 1.5 ATA. A 1.3 ATA chamber is equivalent to 10 feet under.
Note 1.75 ATA is equivalent to 24 feet under. Some 1.5 ATA chambers can go to that level but not cleared for that level. This is dangerous and can give the bends. Those attempting to go to these higher levels such as the hard shell chamber should be monitored. Those preparing for an immediate game will NOT want to stay at this level for long lengths of time.