Are we really advancing the hobby?

[akwarium]

I'm not so sure about that. About 10 years ago when I first started in this hobby I had a 4ft clear-seal for about a year. It was chock full of plants. No co2 or anything until I started to try and grow HC towards the end. Anyways, After about 3 months when the plants had matured I hardly ever did a water change, and I do mean hardly ever and the parameters were pretty much 0 all the time. So I do think its possible, with a big enough tank, the right light and the right stocking that you could let nature get one with it. How, I have no idea as I will admit that this near perfect balance I achieved was pure luck and I have never managed to do it since.

So I don't think people are stupid or lazy or an idiot to try this approach as it is obviously possible. I just don't have a lab to set up umpteen tanks and try numerous things to try it again.

1 Nitrification is an acidifying process, the conversion of ammonia to nitrate leafs excess H+. overtime pH en alkalinity (KH) will drop. Water changes are there to restore those values.
2 we can only measure so much, we have a handful of mostly indicative tests. Water quality is also about all kinds of other stuff, organic waste etc. Those who measure EC or TDS know that no matter how much plant growth, EC/TDS will always rise, more and more solids get dissolved, it may go reasonably slow, but will never stop.

It's not a law to do lots of large water changes, and your tank and fish may still do ok if you don't change water for a few months. But water quality will go downhill without a proper water change from time to time.

 

[Soilwork]

1 Nitrification is an acidifying process, the conversion of ammonia to nitrate leafs excess H+. overtime pH en alkalinity (KH) will drop. Water changes are there to restore those values.
2 we can only measure so much, we have a handful of mostly indicative tests. Water quality is also about all kinds of other stuff, organic waste etc. Those who measure EC or TDS know that no matter how much plant growth, EC/TDS will always rise, more and more solids get dissolved, it may go reasonably slow, but will never stop.

It's not a law to do lots of large water changes, and your tank and fish may still do ok if you don't change water for a few months. But water quality will go downhill without a proper water change from time to time.

And exactly how does one measure water quality? About one of the best indicators I know of is BOD and that takes at least 5 days.

There it is again. Organic wastes. Every time I ask someone exactly what these ‘organic wastes’ are and how they affect the system they just go blank ‘you know, like wastes and stuff, organic ones’

Secondly, what is actually supposed to happen when pH and KH drop? What happens if KH runs out completely?

 

[Affinis]

Those who measure EC or TDS know that no matter how much plant growth, EC/TDS will always rise, more and more solids get dissolved, it may go reasonably slow, but will never stop.

This may be the case with high tech or fertilised tanks, but in my experience with very low tech systems the opposite is true. My TDS drops consistently by one or two points a week on average. I certainly don’t have to do water changes to keep it under control. In fact I’m more likely to use a water change to push the KH back up, but with my hard water it takes years to hit this stage.

 

[akwarium]

There it is again. Organic wastes. Every time I ask someone exactly what these ‘organic wastes’ are and how they affect the system they just go blank ‘you know, like wastes and stuff, organic ones’

That question has a nearly endless row of correct but incomplete answers. compare it to the question "what are books about?"

Organic waste can be, and will be, many things. The only thing they all have in common is that they are carbon based. Other characteristics differ, some might be beneficial (to some extent) others mostly harmful. Everyone who has ever bred fish and raised fry will tell you that daily water changes increase growth significantly. I think it is safe to say that removing organic wastes is beneficial if not necessary. (and it is also the "natural" thing to do)

wen we measure KH we are measuring alkalinity. alkalinity will probably never reach 0 (because of conjugated bases) but it can come close . pH may drop to 5 or 4, that won't kill most fish immediately, but will harm them over time.

again, i'm not saying that you should be changing your water all the time, depending on stocking levels, plants, filtration methods, substrate, additions, the water chemistry you start with, needs of the fish etc, small water changes once every few weeks might be enough.

i am only protesting against the idea that you can do totally without changing water, or that it would be preferable.