a 100% water change once a week will put your fish at risk... and IT IS COMMEN KNOWLEDGE that you DO NOT do a 100% water change once a week. Wether you started doing it without knowing what you where doing... or wether some goose told you to do it... you just dont. That is basically called dismantling your tank... there is NO good reason to dump your tank unless you are starting from scratch, disinfecting for a disease or are doing a complete decor restructure in which case you would keep most of the water anyway.
This forum is about education and helping people.. not about passong on incorrect information. If someone new to the hobby came through and read that 100% water changes weekly are the right thing to do then thats one more person risking their fish stock that it just might not work for.
Im not trying to put anyone down.. and i know im coming off a bit upfront... but if ya learn to do things the right way from the start then there will be no dramas down the track.
Also along with the wastage of water... dumping hundreds of liters every week... when you just DONT HAVE TOO and DONT NEED TOO