"Elaine T" wrote in message
m...
Mario wrote:
Despite some pretty intesive searching, I cannot seem to find any
guidelines (and I'm not even looking for anything *definitive*), on
what constitutes "too high".

I'm about 10 days into a new 20-gal tank with 3 zebra danios. In
addition to keeping an eye on fish behavior, I monitor the pH and
nitrogen levels just about every day. NH3 levels are starting to rise
(still 1ppm) and NO2 is zero.

What NH3 value is considered "too high" where I should perform a water
change?

How about for NO2 (nitrates)?

Thanks in advance,

Mario

Problem is, the toxicity of ammonia is changed by the pH so there is no
single answer. Fish tolerate NH3 much better than NH4+.

Just a typo. I think you had that reversed, as NH4 (ammonium at low pH)
is not toxic and NH3 (ammonia at high pH) is very toxic.
--
www.NetMax.tk

And different
fish can tolerate different levels of ammonia. I generally start to
worry above 1 ppm in a pH 7 tank. However, there is no need to expose
your fish to ammonia. I would strongly recommend using AmQuel while
your tank cycles. http://www.novalek.com/korgd28.htm AmQuel makes the
ammonia non-toxic to fish but it can still be used by the bacteria.
Note that you will get weird readings on typical FW ammonia kits once
you have added the AmQuel.

For nitrite, I don't like to see it above 2 ppm, so that's where I
start thinking about a water change. Change too much water though, and
you'll prolong the cycle. Also watch your fish closely. If they start
getting lethergic and gilling hard, they are experiencing nitrite
toxicity.

--
__ Elaine T __
__' http://eethomp.com/fish.html '__