CO2 buildup

[Nemrod]

Pure food grade silicone will have no ill effects to humans.

There is more likely to be a CO2 issue with a single hose, after all, your rebreathing about a cup of used air each breath. The facts are that with either a double hose or a single hose CO2 poisoning is highly unlikely and probably impossible and not a concern.

Well, impossible, well, there are people who can accomplish anything.

Nemrod

[JES]

.... Well, impossible, well, there are people who can accomplish anything.

Nemrod

To quote Douglas Adams: "A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.

[treasureman]

I removed the sticky valve and replaced it with one of Bryans new ones. Went down (diving that is) no more problem.

The valve i took out was a original; USD silicone, which although in great shape, clearly had some issues. Now its in the trash and all is right with the world

[Firebrand]

Perfect! Sometimes an increased effort in breathing alone, in or out, will cause some issues like that. Glad you got it all smoothed out.