wow that goes against so so so many mantras in WC.
First of all that water has all types of crap in it that is bad for the watercooling system. I'm sorry but his blocks aren't breaking down because of the galvanic reaction, its because of all the chemicals in the pool water.
Corrosion:
All of the materials; PVC, ABS, other hard plastics, stainless steel on the pump housing, copper on the manifold and waterblocks, and gold plating on the waterblocks will all likely react with the chlorine to some extent - but not to any degree that will cause problems in the near future. These materials are all prevalent in swimming pool equipment already.
Vinegar run in a loop will eat a rad away.
I say in less than a years time his hoses and other components will slowly develop leaks until some day his WC goes breaky and destroys his entire system.
This is the reason I will not let normal users use watercooling. I refuse to install it or upgrade it into any computers for anyone.