water cooling reservior build up(white crystal)??

[fondoo]

i've been running my water cooling system for two weeks straight and
today i found some build up in the alumnium reservior. does anyone
know what this is and how i can prevent it??
http://home.rochester.rr.com/fondoo/DSC00003.jpg

http://home.rochester.rr.com/fondoo/DSC00004.jpg

water cooling reservior build up(white crystal)??

[Kingslayer]

You're using tap water arent you. If you are it could be a few things, but it looks like either salt or calcium deposits maybe even flouride. Does your car spot if you wash it with tap water and don't dry it off?

What is your water-block and radiator made out of, and also are you using any additives like anti-freeze or WaterWetter? If your using different metals, ie aluminum waterblock and a copper radiator, the galvanic monster got you.

[mudguts]

Kingslayers right..I work in the auto-repair industry and have seen some vehicles that look absolutely apalling as a result of their owners just using straight water...their waterpumps and radiators were literally crumbling. You should always use a Glycol based antifreeze in aluminum cooling systems for autos and for the same reason on our cooling systems. Water Wetter is best I believe as anti-freeze has a negative effect on cooling. Looks like you caught it in time before some serious damage occured.

[batboy]

This should really be posted in the cooling section, not the Intel CPU section.