why do my rainbows like dirty water?

[zachjohnson65]

Well not really dirty water, i usually changed 20-30% weekly but I have had things pop up and the water changes have been pushed to 20-30% every two weeks. The fish have changed to spawning colors and are digging pits all the time. What gives i thought clean water was key to breeding conditions and good colors. I'm not trying to breed I'm just curious. thanks zach

[bushwhacker]

did they start this behavior after the first delayed water change?

[zachjohnson65]

well there have been two occasions where they have gone 2 weeks and always on the 2nd week they color up and start digging. Normally they are boring blah colors, no digging.