Why do water changes?

[kyle at onebox_com]

Hi everyone,

I know that we are supposed to do regular water changes (I do mine weekly) even with planted tanks.  My question is why?  I'm not doubting they are necessary, its just that I'm having a hard time articulating exactly what is accomplished by doing them.  Essentially my reasoning usually comes down to something like "to remove bad stuff", hardly scientific.

With a non-planted tank it is is much more obvious to me why we do it since there is nothing to pull waste products such as N, P, K, etc. from the water.  But since plants uptake the minerals in the waste products (especially nitrogenous waste, the main element of concern for fish), just what are we doing by changing the water?

Hopefully by educating me, I can give an educated answer next time I'm faced with this question!

Thanks,

Kyle


-- 
Kyle Williams
kyle at onebox_com - email
(707) 583-2064 x2092 - voicemail/fax