[PSUBS-MAILIST] bellows add

[hank pronk via Personal_Submersibles]

I think we talked about this before, but I can't remember the outcome.   How does a bellows add (O2) system deal with or compensate for negative pressure caused by temperature change.  The temperature  falls for a long time causing negative pressure when I dive in a cold lake.  Is it just a matter of letting the O2 level increase?  It seems to take very little hp air to correct it.  
Hank