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Re: [APD] CO2 and pH control
On 12/15/05, David Grim <grim1214 at bellsouth_net> wrote:
> >From the Algone corporate website:
> "changes in pH are a common cause of fish fatalities. Fish can adapt to
> pH levels, if not broadly out of range, but they can't adapt to bouncing
> levels........Keep in mind to change it [pH} slowly as it causes a lot of
> stress to your fish."
I have some questions about how true that really is, mostly because pH
swings of more than 1.0 happen every time I do a water change and the fish
don't fall over dead from it. Extreme changes of pH -- 3 units or
so -- appear to whack fish. I've seen some people import apistogrammas and
have a box of 50 die within days of dumping them from pH 5 to pH 8 water.
However, I have some questions about how much of that is strictly pH and how
much arises from the change in osmotic pressure.
As for ammonia toxicity and pH, what the heck would ammonia be doing in an
My own observation is that people worry too much about pH and fish. I know
discus breeders who have breeding pairs in tanks with pH running 7.8. I
wouldn't say pH has no impact, but I think it's iimpact is overstated in
most instances and for most fish.
I expect that eventually, as the myths go away, we will discover that the
keeping fish was hampered by large amounts of information that was either
wrong or very much overstated. That's has been the case with orchids,
another expensive, exotic hobby that was filled with misinformation for
"Some other facts about pH
> Ammonia increases in toxicity with rising pH.
> Nitrifying bacteria experience a growth and action reduction starting at a
> pH value of 6 or lower."
> pH certainly does matter to fish. Ever wonder why fish that are
> for Asia to the US or Europe don't die of ammonia poisoning, which they
> produce continuously? A big reason is that the pH of the water in the bags
> stays low enough to keep the ammonia mostly in ionized form, NH4+, which
> signifcantly less toxic than non-ionized ammonia, NH3, which becomes much
> more concentrated at higher pH levels and higher temperatures as well.
> + NH3 = Total Ammonia
> The following table comes from an article by Garrett Glodek in the June
> issue of FAMA Magazine. This info is referenced from an APD post by Neil
> Frank. NH3 is the toxic form of ammonia.
> Table 1. Un-ionized NH3 as a percent of total ammonia (by
> temperature and pH).
> Percent NH3 of total ammonia
> Temp pH
> 6.5 7.0 7.5 8.0 8.5
> 68 .13 .40 1.24 8.82 11.2
> 77 .18 .57 1.77 5.38 15.3
> 82 .22 .70 2.17 6.56 18.2
> 86 .26 .80 2.48 7.46 20.3
> I have been accused of having backwards thinking before, so no problem
> there. But to say that pH has no significance for fish is spreading
> dangerous misinformation.
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