extra slim coat during water changes

[philhawk]

it seems that when i do a water change my clown knife gets patches of extra slime. so much so that air bubbles get attached to it. they come off rather quickly after the change is done.

this doesnt happen any other time. any ideas why that would happen?

 

[guppy]

Change of pH is most common cause, such as higher pH in tap acidifying in tank to what is normal for the fish, change in dH, change in salinity, slight chloramine residual, or even temp. diferrence can also do it, and some fish like a few morymids do it if stressed.