Question: You are swimming along the deck of your favorite wreck. For some reason your PO2 is dropping, causing frequent oxygen injections to catch up to your stepping. You keep dumping gas. What’s going on?
Answer: It is possible that you have a leak in your ADV that is causing small amounts of gas to sneak into the counterlung. If your rebreather has a manual diluent injection button, that could also be leaking. Failures always require you to abort the dive, but you can diagnose the problem on the dive boat by removing and replacing the diluent connections to the counterlung or ADV if your rebreather will allow. If fixing those connections does not help, then you may be in need of service on your diluent first stage.
