nc_nutcase;3242711; said:The bacteria that makes up our "biological ecosystem" lives/grows on surfaces and does not live free floating in the water... therefore changing 100% of the surfaces is a bad idea, but changing 100% of the water is not...
Naturally if you neglect to add dechlorinator then the high level of chlorine may harm your bacterial colony, but this is the result of not adding dechlorinator, not the result of a 100% water change...
my water is GREAT for my fish .. never had a problem .. also did a 90% w/c once and most of my fish lived .. but it was because of a leak .. but its still not something that i would suggest people do all the time .. why not do smaller but more frequent w/c?