johndiver999
Contributor
Here is why, this configuration became obsolete about the mid 1990's with the advent of commercially produced din isolator valves. And by the 2000's just about every manufacturer were making din isolator valves at a reasonable price.
I used independent doubles back in 1995 (and Sherwood had a decent isolator valve then), as did a lot of tech divers, and even we didn't reverse the one tank. But "we" quickly learned how stupid that configuration was.
Fast forward to 2021, you have a PADI Master/TecRec/ TDI Trimix Instructor hocking a 20 year old obsolete configuration, but worse, adding his won special convolutions to it.
To steal a quote from a "famous" tech diver, a video like this is "Farm Animal stupid".....
Thanks for the explanation. I see others have added some more specificity in their critique - which is helpful to those of us who are uninformed.