The actual signal on the output of an AD converter looks more like B.
A looks like a parallel link: the 3 bits are sent at the same time via different, parallel paths. A can also be used as a more symbolic interpretation: instead of showing the output bit by bit, it shows the output sample by sample.
B is a serial link: the bits are sent one after the ...
Link them up exactly as you would with a guitar amp -
guitar > pedals > amp/Scarlett.
Analog effects pedals don't have latency. Only once you go through the computer will you see any latency at all.
If the Scarlett has a 'through' setting that avoids going through the computer before it can send to headphones/monitors, then you can avoid that too.
Andy Farnell's Pure Data patches sure will help you a lot!
It would be nice if you specified the kind of water sounds...
Anyway, here you probably have most flavours you want:
Go and get them :)