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RE: [Killietalk] filter
Chris <cgraseck at optonline_net> wrote:
Ugg! First ammonia is not toxic, now nitrate is not toxic at 100s of
I don't know who said ammonia wasn't toxic. It hurts fish at levels of a
few parts per *billion*. 6-8 ppb is enough to permanently damage gills
of very young fish. That is well documented in the aquaculture
literature. [e.g., Burrows, 1964 on salmon]
Ammonium, OTOH is pretty harmless at a few ppm. The amount of which of
them is present is dependent on temperature and pH. There is essentially
no ammonia at 20C and pH below 6.5. At pH=9.4, it is about 50-50
ammonia and ammonium.
Rule of thumb to remember: The fraction as ammonia at pH of 7 will be 70
times higher if at a pH of 9. [10X as high at pH of 8.]
Either my aquarium education is full of hearsay or I'm getting old.
Maybe both. I do have to say that I've read many observations of fish
and invertebrate behavior changing with respect to nitrate
concentration. 40 ppms sticks in my mind as being a point where many
Tanganyikans will stop spawning. I realize that reefing is a different
story but I'm sure my reef would not look good with 100s of ppms of
nitrate floating around.
I know the reef folks have a real fear of nitrates, but I don't know the
mechanism or what it does to inverts. Nitrate certainly behaves
differently in salt water, for that's why protein skimmers can work
there, to remove it, and don't work in fresh.
Mostly, AFAIK, the problem with Tanganicans and similar fish is the high
pH of their environment makes too much of the ammonium convert to
ammonia and they can suffer mightily from that. Lack of plants can make
the situation much more unstable than with normal planted tanks, and the
high metabolic rate of fish like *Lamp. tanganicus* and their big
appetites make them a serious problem to keep.
[I had never heard the 40 ppm keeps fish from spawning argument, nor had
I ever read any credible descriptions of behaviour change in high nitrates.]
Spotte, in _Fish and Invertebrate Culture_, 1970, flatly states that
"There is no conclusive evidence that nitrate or phosphate is directly
toxic to aquatic animals." [p. 50]
At the endpoint of "cycling" it is very rare for nitrate to go much
above 20 ppm. The situations I'm aware of were from overdosing of
fertilizers, like KNO3, and the elevated levels didn't seem to cause any
problems with the fish, as long as no denitrifying factors (like old
carbon filters) were present to produce nitrite or ammonia. Baensch and
Riehl  advise avoiding levels above 150ppm of nitrate as the
denitrification can be encouraged. IDK how much I trust them, though,
for they also claim plants can't use ammonia and must have nitrate for
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