With Fish-In cycling you never worry about how many bacteria are in the water. The bacteria you care about are already attached to media in the filter. Even when you take out most of the water in a large water change there will still be plenty of bacteria to keep adding to the growing colonies and most of the growth will come from cell division of other bacteria right there in the filter. The advice is correct - you can do another water change as soon as an hour after the previous one if either of ammonia or nitrite has not been lowered to between zero ppm and 0.25ppm and getting those stats and maintaining them is your most important goal.
OK, let's get more detailed about the refilling of water bit: (I'm well known for belaboring things
)
(In all cases you add conditioner to the tank when you add tap water directly to the tank.)
1) You can hook up a garden hose, run it into the room and fill the tank directly. This works well if you've got a really large tank and the percentage is not that great, as its actually unlikely to lower the tank temp more than 2 degrees anyway and besides the fish like it.
2) You can hook up a garden hose to a utility sink that has a garden-hose type faucet and do the same thing. Same problem of too cold may apply here too if its not a mixing tap.
3) You can put an adaptor on a non-mixing sink/tub faucet, still same scenerio.
4) You can put an adaptor on a temperature mixing sink/tub faucet. Depending on the type of faucet you may be able to adjust the temp beforehand. Put a large cup of tank water on the sink and alternate your hand between that and the running water and match it, leave the modern faucet at that temp position, attach long clear siphon hose to the adapter, make sure the other end it captured and stable in the tank and turn on the water gently, check its ok at the tank, go back and turn up the force, go back and watch it fill the tank quickly, go back and turn it off before it runs over! When I do this I dump about half the dechlor amount in beforehand, half near the end of the fill or afterwards.
5) If your mixing tap is not modern, you will have to run the hot beforehand, making sure hot is really coming out, then turn it off, hook up the hose to the adapter, start running it into the tank and adjust the temp by running back and forth from the tank a couple times. In all cases temp matching only needs to be rough and probably best to be slightly cooler than the tank water rather than hotter.
Does this make sense? Buckets above the tank level are not necessary, although that's fine if that's what you want to do or its easier. On big tanks you can sometimes put a big board across the corner of the tank to support the bucket but you should always judge that you are not straining the tank or in danger of it falling.
Also a technical note: I am describing this for typical beginner communities of common tropicals. There are hobbyists with delicate fish and hobbyists with time and the desire to carefully pre-condition and thermometer match their bucket water and this is bound to be more ideal, so its fair that I make you aware of that. On the other hand I thing the majority of fishkeepers here do the quicker type things I've described above and many very experienced hobbyists just hosepipe cold water in there full force! For beginners who still have under-six-month-old filters, I feel rough skin temperature matching makes sense.
Whew!
~~waterdrop~~