Dahlia said:Why would there not be a build-up in a non CO2 tank, but there would in a CO2 tank? How long has the tank you don't do water changes in been running? What's in it? That's pretty unconventional, and I'm not sure I agree with it, so I'm curious about your setup.
Because the rate of growth is much slower and so are the inputs of nutrients(fish food/waste, some from the substrate). Plants are pruned and this is export of the fish waste. The input= the output.
When you speed an ecosystem up(just like farmland etc) you must add more inorganic elements to it to maintain this higher rate of production and export.
What goes in, must come out.
This balance is not going to change.
The export is a few cuttings/pruning once every month perhaps and the inputs are fish food. The tank has been running for 18 months, others have been running for several years and a few for decades. It's an issue of balance.
Doesn't matter whether you agree with it or not.
Nor is it unconventional.
It's being done and has been for many years. Discus have bred in tanks with not water changes for 2 years. If fish are breeding....they are generally doing well.
There is often a great deal of banther on the web about CO2, less so with non CO2 methods.
For most new folks that over feed, impatient etc, water changes and CO2 are a very good idea. But folks do not want to spend the $ for the CO2 or are suspicious of it, say they do not want the plants to grow fast, then go out a buy lots of light and want to grow difficult plants.
There are trade offs with each method.
The simpler and easier method is without a doubt the non CO2 method planted tank. You do not put a bunch of fish in these tanks in the first place.
You can have a good levels of fish stocking, but not like many hobbyist often attempt.
The faster you drive any plant system the more you begin to rely on inorganic nutrients.
Regards,
Tom Barr