Lee,

> My computers (I
> usually carry two) require me to reset my gas before every dive once I've
> used something other than air.  If I don't, they set themselves to 50%
> oxygen and 79% nitrogen (very conservative on both gases just in case).

One computer sets itself to a mix that totals more than 100 ??? Why ?

- And why is 50% oxygen more conservative ?

> Had I left the computer set for air when diving nitrox, the importance of
> understanding what's going on becomes even more important.

You mean the other way around, right ?

Bjorn