Quote Originally Posted by cavemark View Post
The con I see is the possibility that in a real situation you may open instead of closing the isolator and waste valuable time until you realize the mistake. Unless you practice your valve drills single handed (I just realized that I need to start doing that) and you have to isolate with your non-dominant hand, it would be very easy to open instead of close. I feel more comfortable with the valves fully turned.

My first day of cavern I was told to open the valves fully, unlike the way taught in OW class where you open all the way and then close a little. That way you know if you have been making contact sufficient to turn a valve.

Mark
But if you only crack the isolator about 3/4 of a turn, you know when you go to close it if it takes more then that then you are going the wrong way. I also do not like to open my any valves all the way untill the stop and leave them there, just in case the same up. I can't tell you how many time when filling tanks that someones isolator was stuck up because they leave it open all the time on surface and during dives. I had isolator I had trouble closing on land, there was no way someone could do it underwater. So at least make you are shutting or checking your isolator. I personal shut mine after I fill my tanks incase of a leak or for traveling incase the valve gets bumped open, i dont loose all my gas. Its saved a dive or to for me and def found a leak or two.