Of course none of us pay anything for water- it's free. And we do not have to pay any electricity bills for running pumps to refill or empty tanks. Plus we don't have any chlorine/chloramine in our water supply for which we need to use dechlor every time we change water.
Here is another amazing fact. In a river the water is changing conctantly 24/7 and at a munch greater rate thanwe will ever do in a tank. Yet in nature there are plenty of microgranisms that process ammonia, nitrite and even nitrate. All that water doesn'y preven them from colonizing.
His tanks are being fish in cycled. In the end there are enough microorganinsms and plants (assuming there are some in the tanks) to handle the nitrogen compounds. With no plants, than any nitrate must be manually removed the way we all do it, a 50% weekly water change.
As long as there is any ammonia in a tank, the mircoorganisms will come. And if one adds live plants, they host the bacteria as well.
The thing about nature is it works whether or not we want to believe it.
And then there is the fact that to get a decent view of the microrgaisms at work requires magnification of at least 2,000 times and to see individual cells it is more like 93,000 times.
https://www.researchgate.net/figure...th-magnifications-from-2000-93_fig2_272641034
The only clue we have that these things are in our tanks in the millions is we do not test ammonia or nitrite. If we have live plants involved and media which ultimately develops denitrification, we never see nitrate either.
The one thing to which we still must be alert is that the water parameters for our source water change. In the 23+ years I have been using well water the pH range has been 6.9 to 7.4. The TDS range has been as low as 53 ppm and as high as about 115 ppm. However the averages have been 83-105 ppm for more extended periods. I do not use dechlor as we have our own private well. On the down side I have the most expensive electric utility in the country in a major area. The water if free, getting it out of the ground and in and out of my tanks is not.
Btw- I change 50-60% of the water weekly in all my tanks and have for the last 23+ years. I also cycle them or the filters for them as well. I mostly also stock heavily. A lot of this is due to fish spawning. The only tank I ever cycled with fish in it was my very first tank.