I have had a similar need to dive in 10 feet of water to service my lake water intake. By the time I get down to where I need to be I am out of breath.
I considered buying one of these mini scuba tanks but have not done so yet. In the meantime I am not getting any younger so I know it won't get any easier!
https://www.amazon.com/CHIKADIV-S300...1zcF9hdGY&th=1