Explain GH vs. KH to me

[golfproinlexky]

Can someone please explain the difference of GH and KH to me? My KH is about 3 and GH is off the map at 18 (hard tapwater to start). How does this effect plant growth, algae, cyano, O2 and does CO2 cause water to get "harder?"

Can't wait to hear your feedback.

 

[Sploke]

Great article on water chemistry

http://www.aquariacentral.com/forums/showthread.php?t=85207

 

[chinnp]

There's a pretty cool article on it in the articles section. It's written by a devilishly handsome guy too. Basically KH is the elasticity of your water. The higher your KH, the more likely your water will flip back to where it was before if you try to adjust the ph or other characteristics of the water. High KH is like a rubber band. You can bend it wherever you want, but it'll go back to shape it was when you lay it down. Low KH is like a paper clip. You bend it and you'll never get it back the way it was.