Yep, end of tank dump, wondered why I was having trouble getting the diffusers to act right. One larger tanks , I often check the gas level, but on the smaller set up I have not changed it for 2 years now and figured it might be the tubing etc, but nope.
Then no gas came out today and I knew it was something else right away.
So if you think you are an expert, it really does not matter, the hobby will always make you think twice and rethink thing and be more humble.
At least I can take my own advice and know I can rule most things
It's just the things that you do not think about that will get you.