Derek Broughton wrote:
Altum wrote:
Derek Broughton wrote:
Altum wrote:
Yes, but it's _still_ much less toxic than ammonia.
Put it in alkaline water (as in most ponds) and it promptly loses a
proton and becomes ammonia.
"most ponds"? I think you'd be hard pressed to prove it. I'm not
convinced your chemistry is right, either - mine's way in the past, but
it doesn't seem valid to me.
What part of "pKa of ammonium = 9.2" is unclear? You can verify that
number anywhere. If you have forgotten what a pKa is, you may want to
go back to a chemistry text and review the Henderson-Hasselbach
That would be Henderson-Hasselbalch...
ROFLMAO. Nice catch. But you see what I'm getting at - it doesn't
matter what form the ammonia/ammonium is in when you add it to buffered
water. If you add ANY form of ammonium salt or ammonia to typical
alkaline pond water, some of it will end up as toxic NH3, with the ratio
set by the pKa. There is no functional difference in a pond buffered
with 100 ppm of carbonates between adding 0.1 ppm of ammonium salts or
0.1 ppm of household ammonia (mostly NH3). People shouldn't read a
fertilizer label and think it's safe to put an ammonium salt into the
_water column_ because it's not ammonia.
equations and buffering chemistry. Knowing about the pH-dependent
equilibrium between less NH4+ and NH3 is fairly fundamental to aquarium
and pond chemistry.
For those who don't know what Altum meant, there should be equal amounts of
Ammonia & Ammonium in a pond with a pH of 9.2. That's _really_ high for a
garden pond and the first thing I'd want to do is get it down. Since
getting a pond down to about 8.4 is really pretty simple, and the ratio of
ammonium:ammonia is about 10:1 at that pH, I'd suggest it's not as serious
a situation as he says.
I dunno. I've kept systems at pH 8.4 and if there is enough free
NH4+/NH3 to show up on a typical test kit as the system cycles, it's
enough that the fish will be flashing and jumpy. Koi and goldies are
very tolerant of water conditions, but we all want to keep them in the
best possible conditions.
See http://www.reefkeeping.com/issues/20...hf/index.php#2 for a nice
graph (slightly different from our situation because of salt water, but
close enough).
Now, if we're going to revise the argument and point out that it doesn't
matter that _all_ of the ammonium won't instantly become ammonia, but that
any amount of ammonia is a Bad Thing (TM), I'd pretty much have to agree
and point out that that's one reason why planting in clay soils is usually
recommended. If you're going to fertilize lilies, you should plant in a
clay soil, and use solid fertilizers in the soil. Not much will migrate
out of the clay before being used by the plant.
I'm a strong believer that any unnecessary ammonia is a Bad Thing (TM).
Even the 10:1 ratio of ammonium to ammonia at pH 8.2 can cause
long-term stress and problems at levels that are difficult to register
on a test kit.
But this whole thing started with bare-root lilies. I have many plants
that take their sustenance from the water column in outdoor setups (WH,
water lettuce, elodea, watercress in the spillways, and even submerged
swordplants and grasses). The nitrogen and phosphate demand of the
plants far outstrips what the fish and foods provide. Add a little KNO3
and KH2PO4 to the water and I get healthy plants with lots of flowers.
(And my bluefin killies breed like rabbits so I'm certainly not hurting
the fish.)
Liquid Miracle-Gro was mentioned as a possibility for bare-root lilies
and I stated that any fertilizer considered for fish pond water, not
soil, must be completely ammonia-free.
However, it's all complicated by the fact that bacteria are constantly
converting ammonia to nitrite & nitrate, and _any_ pond can remove some
amount of ammonia from the water - which is why so many people manage to
continually top up their ponds with tap water without killing the fish.
It can, but we're back to the Bad Thing(TM).
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