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Posted by David on March 12, 2005, 12:02 pm
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The thread a few days ago, started by the chap who said that his setup
worked better without any water changes for over a year set me to
thinking. Just how bad will things get in my own betta tanks, even
*with* water changes?
Having no idea what to expect, I wrote a simple computer model and was
surprised by the results: If there are no other mitigating processes,
(filters, plant converters, etc.) involved; only water changes, then
the concentration of pollutants, (urine, feces, etc.), appears to
asymptotically stabilize to a fixed value after a few weeks of water
changes. (The number of weeks depends upon the percent of water
changed, and the rate of fish excretions; but if these stay the same
then the concentration of pollutants stabilizes.) This seemed
counter-intuitive to me, but at least comforting.
Oh,... yes, I am assuming that the mulm is "stirred up" at the time of
water changes -- you don't get all of it, just a proportionate amount
of it.
If anyone is interested, here are some results:
%WaterChange, StableConcentrationMultiple, #Weeks
25, 4, 20
33.33(one third), 3, 15
50, 2, 7.5
100, 1, 1 ... (of course)
Interpreted: if one does 50% weekly water changes, the concentration
of pollutants will stabilize at 2 times the initial concentration
after eight (7.5) weeks.
I feel better now, as this is what I have been doing. The bettas are
in gallon jugs, and (very surprising to me), the ammonia levels have
remained at zero for eight weeks now. But the jugs are stuffed with
plants so that, I am assuming, is the explanation.
However, since both fish and plants seem happy, I guess that I am
concluding that a stable concentration of two weeks worth of feces and
urine is acceptable to both... But I will be happy to hear anyone's
thoughts!
Regards, David
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Posted by Richard Sexton on March 12, 2005, 12:55 pm
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>The thread a few days ago, started by the chap who said that his setup
>worked better without any water changes for over a year set me to
>thinking. Just how bad will things get in my own betta tanks, even
>*with* water changes?
>
>Having no idea what to expect, I wrote a simple computer model and was
.
.
.
>
>Interpreted: if one does 50% weekly water changes, the concentration
>of pollutants will stabilize at 2 times the initial concentration
>after eight (7.5) weeks.
Correct.
>I feel better now, as this is what I have been doing. The bettas are
>in gallon jugs, and (very surprising to me), the ammonia levels have
>remained at zero for eight weeks now. But the jugs are stuffed with
>plants so that, I am assuming, is the explanation.
>
>However, since both fish and plants seem happy, I guess that I am
>concluding that a stable concentration of two weeks worth of feces and
>urine is acceptable to both... But I will be happy to hear anyone's
>thoughts!
I wrote the same program and made a web interface to it. You
can play with it here:
http://aquaria.net/sys/tank
--
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Posted by NetMax on March 12, 2005, 1:35 pm
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>>The thread a few days ago, started by the chap who said that his setup
>>worked better without any water changes for over a year set me to
>>thinking. Just how bad will things get in my own betta tanks, even
>>*with* water changes?
>>
>>Having no idea what to expect, I wrote a simple computer model and was
>
> .
> .
> .
>>
>>Interpreted: if one does 50% weekly water changes, the concentration
>>of pollutants will stabilize at 2 times the initial concentration
>>after eight (7.5) weeks.
>
> Correct.
>
>>I feel better now, as this is what I have been doing. The bettas are
>>in gallon jugs, and (very surprising to me), the ammonia levels have
>>remained at zero for eight weeks now. But the jugs are stuffed with
>>plants so that, I am assuming, is the explanation.
>>
>>However, since both fish and plants seem happy, I guess that I am
>>concluding that a stable concentration of two weeks worth of feces and
>>urine is acceptable to both... But I will be happy to hear anyone's
>>thoughts!
I find it difficult to draw subjective conclusions on these types of
problems. Objectively, is the point of stabilization comparable to the
environment where the species evolved? Using the same comparison, is the
plant/animal ratio comparable? In the first question, I think most would
say that the pollutant level is much lower in nature, but in the second
question, most would say the plant/animal ratio would also be lower, so
does the plant/animal ratio compensate?
To thicken the plot, even if the plant/animal ratio is higher (keeping
ammonia lower than would be found in nature), what other elements are
building up which we are not measuring and are not consumed by the
plants. We know from practical experience that fish (for all technical
purposes) will partially compensate for this build-up of elements,
probably by becoming saturated with them (our example of the no or little
water changes), and we also know from experience that it has a direct
relationship on growth rates (non-uniformly according to their growth
stage or age).
Without getting too scientific, an established and consistant routine of
water changes will bring the parameters to a stable level, which the fish
will generally adapt to, and if sufficient, prosper to (imo).
> I wrote the same program and made a web interface to it. You
> can play with it here:
>
> http://aquaria.net/sys/tank
Neat little program. A graphical output would really be slick, to see
where things start levelling off. Thanks.
--
www.NetMax.tk
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Posted by David on March 12, 2005, 5:54 pm
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On Sat, 12 Mar 2005 13:35:01 -0500, "NetMax"
>
>I find it difficult to draw subjective conclusions on these types of
>problems. Objectively, is the point of stabilization comparable to the
>environment where the species evolved? Using the same comparison, is the
>plant/animal ratio comparable? In the first question, I think most would
>say that the pollutant level is much lower in nature, but in the second
>question, most would say the plant/animal ratio would also be lower, so
>does the plant/animal ratio compensate?
>
>To thicken the plot, even if the plant/animal ratio is higher (keeping
>ammonia lower than would be found in nature), what other elements are
>building up which we are not measuring and are not consumed by the
>plants. We know from practical experience that fish (for all technical
>purposes) will partially compensate for this build-up of elements,
>probably by becoming saturated with them (our example of the no or little
>water changes), and we also know from experience that it has a direct
>relationship on growth rates (non-uniformly according to their growth
>stage or age).
>
>Without getting too scientific, an established and consistant routine of
>water changes will bring the parameters to a stable level, which the fish
>will generally adapt to, and if sufficient, prosper to (imo).
>
Interesting and insightful perspectives, (as always), NetMax. Thank
you!
R Sexton wrote:
>> I wrote the same program and made a web interface to it. You
>> can play with it here:
>>
>> http://aquaria.net/sys/tank
>
>Neat little program. A graphical output would really be slick, to see
>where things start levelling off. Thanks.
Mine does have a graphical output, but I'm not smart enough to make it
play on the web. And yes it does look kinda slick. However, FYI, the
"# Weeks" column on my OP (below) is the point where it levels off:
%WaterChange, StableConcentrationMultiple, #Weeks
25, 4, 20
33.33(one third), 3, 15
50, 2, 7.5
100, 1, 1 ... (of course)
i.e. it levels off at 7.5 weeks for 50% water changes. (From then on,
it's flat.)
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Posted by David on March 12, 2005, 5:51 pm
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On Sat, 12 Mar 2005 17:55:41 GMT, richard@vrx.news (Richard Sexton)
wrote:
>
>I wrote the same program and made a web interface to it. You
>can play with it here:
>
> http://aquaria.net/sys/tank
Cute Richard!
I feel better now, knowing that someone else was troubled by, and has
already attacked the same problem!
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>worked better without any water changes for over a year set me to
>thinking. Just how bad will things get in my own betta tanks, even
>*with* water changes?
>
>Having no idea what to expect, I wrote a simple computer model and was