Well, maybe if you had bothered quoting my entire sentence, or at least reading it, you would have seen that I never said an aquarium pump WOULD supply enough air volume for a snorkeler.
Just as you, I didn't check, but am concluding from aquariums I owned: An air stream that would have been sufficient for a diver would have blown the water out of the aquarium. All the water, and the fish.
The pump that the other post referred to (remember, that other one that you didn't read, but replied to
), was a pump for inflatable mattresses, dinghies, etc.
How do I know this type of pump has enough volume?
I owned one. And the mattress to go with it.
Inflating it by mouth took me half an hour, and I almost passed out.
The pump did it in a minute or two.
Conclusion: The pump has considerably more air flow than I do.
So much more that I am sure it can sustain sufficient flow even at the back pressure of a few feet of water.
Based on what? Do you know how many CFM of air, at what pressure, an aquarium pump can supply? Maybe there are monster aquarium pumps out there that I've never bothered looking into, but the ones that I have seen are, as you've been told, completely inadequate for providing enough breathing air to a person 5-10 feet underwater.