Sorry, but its a real bad idea. at best, it would be something that would require a lot of maintenance. Do you know how corrosive the ocean is? and as soon as kelp and seaweed wrap around your buckets its going to jam. Too many moving parts there, is asking for complications and then whatever energy you produce probably wont be worth the air compressor you are running, and then you have to transmit the power down a line installed where? in the ocean bed?
You have made some great comments that I will consider.
The buckets will be made of a non-corrosive metal, lightweight aluminum or plastic
A thin screen wire mesh around the buckets should keep out unwanted things
As far as the energy output, that was answered a few posts earlier.
The electric power produced could be cabled to shore which should be a few thousand feet away.
The energy required to compress 40,000 cubic feet of air down to 2,666.66 cubic feet every 2.75 minutes.
The return is a continuous pulling force 118,428 pounds at a speed of 2 feet per second.

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