On 9 Mar 2005 21:39:19 -0800, wrote:

No one (fish, human, etc.) would want to breath the same air (or water
in this case) over and over again in a small room either.

But we all do live in the same air and water, don't we? Isn't it more
important to have conditions in the tank that are livable and not
worry about the ingredients?

It is my experience that water changes balance out lots of problems.
It seems to me that filters do not remove solids, they hold them until
the passing water erodes the solids enough they can pass through the
media. Smaller particles can be more efficiently handled by the tank
bacteria.

That's the
conclusion I came to when I was young trying to determine how important
water changes are. Of course my opinion since that determination is -
change some of the water regularly, and don't take short cuts

I totally agree. Addinging spices to a good soup may make it worse.
I will never forget my early tank experience where I decided to adjust
everything. I did something wrong in the pH adjustment and lost
several fish before I could correct the error. I decided that I was
not capable of managing the tank better than natural forces, including
water changes.

like
chemicals or electrical (just over 10 years ago there was supposedly a
new product that did something like run an electrical current through a
tank and it killed off the bad bugs while not harming the fish so
supposedly water changes weren't necessary,no one believed it and time
telled that that product was all hype, the experts were not
representatives of the water supply industry so in my opinion those
experts that said the device was really worthless were right by saying
water changes are just as necessary as they are before the product was
released and to not use the product - it was too good to be true and
only hype). After all - would you like to breath the same air for
months at a time?
Airliners use recycled air and people still get sick
from it all the time. Those experts never got paid for selling water so
they are practically unbiased. My 2 cents - later!

I think you overdo the "same air" theme. The important thing is we do
reuse air and water. It is great that the natural process is good
enough that life has existed without human intervention for a long
time without our help. No new air or water, but biologically recycled.

But, I don't want to ignore that we have learned to manage special
closed systems, such as airliner air, pretty well. As for my tropical
fish tanks, I trust that the simple trust in the biological processes
plus frequent water changes is the best for my abilities.

dick