[quote]When you get down to it, the only place I have ever seen weekly water changes recommended is in newsgroup and forum posts. [/quote]
Have to disagree
All of the below mentioned are "published" and should all be "reconized"
"A regimen of large, partial water changes and powerful biological filtration should take care of these fish." Vinny Kutty and Wayne Leibel on keeping pike cichlids
"All Geophagines do best in clean water and regular partial water changes"
Leibel, Wayne S. 1993a. A Fishkeeper'ss Guide to South American Cichlids
"T. duboisi is one of the most popular cichlids from Lake ...
The maintenance of the breeding tank mainly consists of a weekly water change" Ad [b]Konings [/b] saw you pointed him out above
in lectures in person Ad also gives the advice of frequent water changes for central americans,plan to hear his talk this weekend and just about guarantee , frequent water changes will be given as advice.
"frequent partial water changes are recommended for proper health and growth" Don Danko - on breeding pike cichlids
"Water changes of 50% were done on a weekly basis to promote health and proper growth." Don Danko - on breeding plecos
"Daily water changes prevent bloat and promote growth and breeding" Ron Georgeone - argueable the best "fish showman" around and breeder of many "hard to spawn species".
"Water changes must be done in large amounts if you are to be successful at breeding angelfish. Angels seem to thrive with 40% or greater water changes done as frequently as possible, even daily. You will probably not have much success with breeding angelfish if you can't change at least 30% once a week." Steve @ angelsplus
" Discus require 25% daily water changes" Bing Seto
"Discus require at least 25% daily water changes" Jack Wattley
"a very efficient outside power filter in conjunction with a program of frequent, regular partial water changes" Paul V. Loiselle,on keeping central americans
"You must change your water frequently. Frequently does not mean once every couple of months. I don't care how big or how many filters you have on your tank, you still need to change your water and clean your filters or vacuum your gravel" Pam Chin on keeping cichlids in general.
[quote]The instruction manuals that come with Aquaria, Inc. products (Magnum, Aqua-Tech, Emperor, Penguin) -- Monthly. The manual that comes with the Whisper (Tetra) 30-60 filter [/quote]
Look up those brands or their offbrands and one thing you'll also notice is they all sell some type of chemical/junk thats something along the lines of "for use btween water changes".
[quote]Monthly changes leaves no time for any measureable accumulation of nitrate[/quote]
In my oponion nitrate is still NOT the only thing to consider.
If your stuck in your house and the air is full of sulphur but the air tests fine for oxgen,would that satisfy you because what you checked was ok? Or would the suplhur still be annoying even though it wasn't tested for?