Originally Posted by iamntbatman
I had a lengthy debate with Tyyrlym I believe a while back on this issue. I'm convinced that, if you're doing water changes with enough frequency and of enough volume to keep ammonia from ever reaching readable levels, you're probably limiting the potential growth rate of bacteria. If a bacterium is sitting there, it needs X amount of ammonia before it's able to divide, and if the ammonia is half as concentrated in the water as it was previously, that bacterium is only going to be able to grab an ammonia molecule half as often.
Whether that speculation is true or not is essentially a completely moot point, though. If you're doing a fishless cycle there's no need to keep ammonia levels low through water changes, and if you're cycling with fish the health of your cycling fish is more important than any extra time the cycle may take so water changes should be done anyway even if it does prolong the cycle some.
That's quite true. But how much water would one have to change to effectively eliminate the ammonia or at least reduce it to the point where it would not be sufficient for bacteria? Given that fish and other organic processes regularly produce ammonia, a 50% water change every day is in my view not going to eliminate it; it will reduce it, obviously, that's why we do it, for the fish as you mention; but if the reading is still above zero (which it usually would be until the tank is cycled) the bacteria will presumably manage.
We know that in a cycled and balanced tank, ammonia should never be detectable by tests, but always at zero. And yet one assumes there are bacteria present in balance with the fish. Plus of course the test kits we use are probably not fine-tuned as scientific instruments so a zero reading may in fact be showing when there is some ammonia present.
Plus the fact that if plants are present, they will generally grab the ammonia before the bacteria can, and then in acidic water the bacteria are naturally fewer.
And my short sentence perhaps needs expanding; in the context of the new tank with ammonia present at levels above what the bacteria can so far handle, the fish must come first, and the intended 50% daily water change will not affect the cycling as detrimentally as not doing the water change will affect the fish's health. As you correctly state, that comes first.
That other lady suggesting more fish be added while doing no water changes is clearly out of focus. This will result in stressed if not dead fish, which at least will increase their fish sales I suppose.