Aquapunk Bubble Logic: Underwater Computing

Ok, so a while back I had an idea for a story set far future where everyone lives underwater. Humanity has deliberately modified their own genes to be able to survive... as merfolk, sea elves and some crustacean variant of orcs. I wanted a fair bit of modern day science to still be available even though modern day resources were not. i.e.:
Underwater means no combustion so no motors.
Projectiles would be lucky to more than a meter or two.
Electrical circuits are probably not going to work.
The ability of these people to breathe requires oxygenated water with low pollutants so any industrial activity resulting in pollutants/particulates(such as mining) would kill people off.

Anyway, two of the main characters in this story were responsible for researching/designing/maintaining computational systems that would work underwater. I figured this would be possible and was inspired by stories such as 'Souls in the great machine' by Sean McMullen and 'The difference engine' by William Gibson and Bruce Sterling.

For other examples of mechanical logic see:
http://mechalogic.wordpress.com/ 
http://xiaoji-chen.com/blog/2010/the-linkage-computer/

Also inspired by: people who build working computers in minecraft.
https://www.youtube.com/watch?v=Sl2pMeTYQo0   -Screen, keyboard input, calculator, music
https://www.youtube.com/watch?v=aQqWorbrAaY  -Screen, keyboard input, commands
https://www.youtube.com/watch?v=KzrFzkb3A4o#t=299 -Ohm's 16 bit computer
https://www.youtube.com/watch?v=gdnO1QZJ--M  -Minecraft in minecraft


Yesterday I came up with a few ideas for bubble based logic gates, today I drafted them up:

They aren't quite up there with minecraft computers and they are probably as buggy as hell but it was interesting.
Simple piston raised by bubbles. The piston shaft has holes which allows the reservoir to output bubbles if the piston is in the correct position.
Considering possible issues with using bubbles as a... bit signal? or something, I added in the 'timing plate'(not really a plate) which I see as something similar to a rotating belt with holes that allow output bubbles to be sent before inputs get released into the reservoir as well as limiting the bubbles that can be output within a single computation cycle.
The use of gravity as power source requires a layered design but it should be easy to design a way to signal lower levels by having the piston shaft and output hang beneath the piston instead of above.
This system would have the advantage of being able to use simple analogue counters by collecting bubbles etc.

A quick spot of googling reveals someone has tried a slightly more professional job of designing bubble logic..
http://web.media.mit.edu/~manup/research/bubble-logic/
Also wikipedia has a page on fluidic logic with an interesting fluidic amplifier.
http://en.wikipedia.org/wiki/Fluidic_logic

So that's it.
The latest task on my maybe-later-but-probably-never TO DO list is building a functional calculator with bubble logic. Maybe have it set up within a glass tank as a lounge table. Brilliant conversation starter.