How can I make my husband understand the oxygen won't help if he doesn't keep the tube in his nose and breath through his nose?

A mouth breather. That maybe the problem. My husband is a mouth breather to. If you can't breath thru your nose, then how do they expect u to use the tubes. Maybe he would to better with a mask?

I never had to carry tanks around for Mom. She had portable oxygen. It was supplied by in home. She used the bigger machine when home. The large tanks were provided but only used if she lost electricity.

Wish I had a good answer, but I don't.  It's hard to adjust to the tube in one's nose.

One thing you can check is to see if there's abrasion behind the ears.  If so, ask the DME oxygen supplier for the little ear wraps.   Ours were some kind of soft rubber (?) plastic (?), that fit over the cannula at the ears.   It helps avoid friction against the skin which can be an irritant and increase the resistance to use the oxygen.

Is he on oxygen 24/7?   At what level?   If he refuses to use it, there will come a point at which his oxygen sat levels decline, and he'll need it more, and might in fact end up back at his pulmonologist's office, or in the ER.  

I would get a good pulse ox to test his SAT levels and monitor them, so you can tell if they're worsening b/c he's not wearing his oxygen.   If you do have to rush back to his pulmonologist, or to the ER, that information will be very helpful to them.  And someone might just give him a very blunt lecture about using oxygen.

May I share some more observations and experience, especially with carrying tanks?

This may harm either or both of you in the long run.   Back in 2004, I carried E tanks, plus a walker and a wheelchair as backup.  Although I had a wonderful Ford Escort station wagon at the time, there still was a lot of lifting involved.   I never thought much about it.

Fast forward, now I have back problems.  I don't know how much of it can be attributed to leaning forward, or gardening, but I think oxygen tanks made a significant contribution.  Leaning in and out of a station wagon's cargo area, as well as a sedan's back seat and trunk, took a toll over time.

Get a back brace to wear when you carry the E tanks.  And the behemoth, which I think is the concentrator as opposed to a portable tank, is a very heavy piece of equipment. 

Ask your health care provider to script for E tanks, as well as the smaller portable ones although they only have a 2 hour capacity.  The portable tanks fit onto a roller, and you can haul them behind you as you walk although they do have to be lifted into a vehicle.

If you can get the ones with interchangeable battery cartridges, they're a lot more versatile and easy to handle than the heavier E tanks.