Hi locust and tag,
I'd like to address both of your last posts. First, tag, yes this is exactly what a thinking person would conclude (that you shouldn't pour that chlorinated/chloraminated water straight into the tank and have it be pumped through the filter where the precious bacteria are..) BUT, in practice this is another of those things that comes out a little more oddly than that: It has been reported in a number of long threads by the very experienced fishkeepers that they in fact just dump tap water in via a hosepipe, without conditioning (!), and have never had their filters or fish suffer. On the other hand, a few others, also experienced, have warned that they have experienced loss of fish this way.
Personally, I've taken a middle path (actually based on what RDD does, the writer of the fishless article, who I think is pretty good at keeping a middle ground... and I think a lot of other TFFers do this too..) I personally think that relatively new tanks have much more fragile bacterial populations and less stability, so I think the use of conditioner is especially important for beginners. (I think the experienced ones often have very well established filter populations which are very tough.) I think its perfectly fine to add conditioner directly to the tank water and tap water directly also at the same time.
However, I like to calculate how much conditioner I'm supposed to use for the amount of tap water that will be added. I then put in HALF that amount near the start of direct filling, and add the OTHER HALF at the end. And here's a new twist: locust is correct in hearing that people often spash in an "over-amount", even double the recommended dose. And in fact there are some good reasons (water authorities sometimes put quite a lot of chlor products in the tap water and you want to get them all) to be sure to do the recommended amount, BUT one of the latest things we've recently heard from the bacteriologists is that in fact it may be that our bacteria, the N-Bacs in particular I believe, do NOT like too much conditioner.
So, my current conclusion is to use all of the amount recommended but not to go too much over (unfortunately less convenient than being able to go overboard as in the past.) Sorry this was so convoluted...
~~waterdrop~~
