A Quote from Aquaponics Nation web
site…
“So here is how I figured out how
much water change I need to maintain the 200mg/L nitrogen level.. I am not
getting the exact same number as you Paul so if I have missed something please
correct me.. Thanks.
We have a Fish tank
(1500L) that has accumulated a 200ppm TAN level.
This tank is getting 11.776 grams
of TAN per day based on 400grams feed and a 32% Protein content.
So 400*0.32*0.092= 11.776 Grams
of TAN (total ammonia nitrogen)
As explained by Paul and in the
Timmons book, Nitrogen doesn't magically multiply when it's being oxidized to
Nitrate. (should have trusted my gut on that in the first place) The Nitrogen
content is still the same, less a fraction that is being absorbed into biomass
of the bacteria oxidizing it to nitrates.. But like Paul said, lets not
complicate it lets calculate based on TAN (total ammonia nitrogen).
The so we have 11.776g or 11776mg
of TAN being added to 1500L of water daily, so 11776/1500= 7.85mg of TAN per
liter is added daily.
When time comes to figure out how
much water to remove to keep around 200mg/L of nitrogen we have to look @what
the level of nitrogen is in the water that we are removing (in this case
somewhere between 200 mg/L) . So the easy way to figure this out would be
to take 11776mg/200mg/L = 58.88 Liters..
if we want to maintain 200mg/L we
have a total of 1500L * 200mg/L = 300000mg of TAN in system. If we remove
11776mg we have 288224mg TAN in the water @ 1500-58.88=1441.12L
If we do 288224/1441.12= 200mg/L
But when we add back the 58.88 liters to our system we
have 288224/1500L=192.149mg/L as the day moves on 7.85mg/L is added to
system, again bringing the total nitrogen content up to 192.15+7.85= 200mg/L
I am sure I am missing some minor
detail to get the math exact.. But in my opinion this will be close enough”
[ED:
And all of you thought the AFS was only for ponds and aquariums…now the Aquaponics
crowd is getting into it.]
So you really think that 10% water
change is doing your pond/aquarium any good…think again!
Here are some excerpts from by blog
that may interest the aquarium hobbyists. Just replace the word ‘pond’ with
aquarium and the same rules apply.
Koi-Vet Forum Question:
Q: How can two major water changes
per year (coupled with replacing losses due to evaporation) possibly deal with
the obvious shortcoming of declining water quality -- other than by simply
denying that it exists?
Don
A: This is a very good question and deserves an astute answer. I
also hope that everyone on Koi-Vet reads this and takes note of this response,
especially any of the newer hobbyists in ponding.
You yourself know about
water stability, decline, and the parameters that must be held in order to keep
our animals alive and healthy along with water changes. Water
quality is always a problem because as time passes, various physical, chemical,
and biological processes working in and around the pond alters the initial
tabula rasa characteristics of the water. However, not all hobbyists are so
inclined to do so, water changes that is, and a number of these people will
only do as much or as little, as they humanly possibly can; “getaway
with!”
With that said; all water changes are dictated by PE (Pollutant
Equilibrium). This is the amount of pollutants being made by the system, its
animals, plants, the filter, and the amount the water that is exchanged from
periodic water changes, will reach what is called a steady state. This also
includes the amount of foodstuffs that are being added to the system on a daily
bases. The fish food itself, will add nitrogen and phosphates to the system, as
you know. The filtration system will be the limiting factor here because of its
capabilities or its incapability to process such pollutants on hourly or daily
bases. If more pollutants are being made/added to the water body proper than
what the execution of a water change can eliminate or lessen to a greater
degree, for the safe keeping of our animals, then a larger filtration system is
needed. Therefore, larger portion of the water mass must be exchange with clean
water, until a PE is then reached.
The only reason we
execute such water changes is because: No matter what kind of filtration system
we use, even a state-of-the-art filtration system, we are still dealing with a
closed system. Therefore, a filtration system will not stop the decline of
pollution in our ponds, but will only slow it down to some degree, and the
degree of degradation is determined by so many factors that it would be
anyone’s guess as to what the causes of the insults are and what the outcome
would be on the system parameters. Therefore this judgment on water changes
will be based on an “individual’s decision,” on when, and how much and why such
will be conducted.
I will also quote right
from my free iTunes Book if I may: “Even with the Anoxic Filtration System, as
good as it is, still needs to have at least two partial water changes made each
year. Generally, the greater proportion of water that is changed during the
filter clean-out, the lower the stabilizing pollutant level in the pond would
be. Because of this filtration systems capability, the Pollutant Equilibrium
levels are reached within a short time-span of weeks instead of months, without
all the frustrating water changes and the cost of doing them.” I believe that
the hobbyist is reading this one section of my free iTunes Book and taking it
to the bank, as to say.
You must read my whole
book and then one can determined that if Nitrates are eradicated
and /or diluted to a greater degree by the filter, then water changes for Nitrates
(N03) sake, is not a prerequisite for keeping our pond healthy. In
fact, I give this as an example in my free iTunes Book: “For example, lets say
you have a pond, for the sake of argument will say this pond is 3000 gallons,
that is producing 8-ppm (ppm = parts per million) of nitrogen (NO3) every
month, this now becomes a constant.” As we all know, Nitrates; are only
a small constituent of the amount of pollutants that our ponds have to deal
with. In no way did I ever say or advocate in my book, that if you use my
system, water changes can be eliminated or that only two water changes a year
will suffice, no matter what the pollution equilibrium is or is not! I myself
cannot, and will not, second-guess what a ponds pollution mass to insult levels
are. In fact I will quote from my book once again: “There is little argument
whether or not a periodic partial water change is necessary in order to
maintain a healthy pond that fish can live in without undue stress. I also
think that all hobbyists would agree that all ponds would benefit from more
frequent water changes, and generally this would be “the more frequent the
better.” Does this sound like a person that only advocates two water changes a
year?
However, I also must add
that there are several hobbyist using the Anoxic Filtration System that only do
one too two large water changes a year with excellent results in fish growth,
heath, ect., ect., for many years now. Because this is a repeatable constant,
there must be some legitimacy into what I say in my book about me only
executing two large water changes a year in my testing pond.
As you have already stated
there is more to the pollution picture in a pond than just one end-byproduct of
a specific bacterium. Any hobbyist can supersede the filtration capabilities
and you and I have no control over that. However, if the pollution constants
are, let say, too much food or over stocked pond, no filtration system made for
the hobbyist will overcome these insults. Not even the Anoxic Filtration System
for that matter. I see this with people using the Nexus system, were they add
on supplementary filtration to an already expensive filtration system, just to
handle what the filtration system itself cannot.
Too many hobbyists
that read my free iTunes Book only read the words “still needs to have at least
two partial water changes made each year” thinking only; “two partial water
changes a year, great!” Of course, that is not what I say at all. As you can
see this is the bare minimum that I recommend, and even at the bare
minimum, hobbyist that uses this system will not even do that much, believe it
or not! My system is good, but it can’t make a silk purse out of a sow’s ear.
However, I must interject here with an observation that a 10% water change a
week would be useless, if the hobbyist does not know what their PE is to begin
with.
I also stated in my book: “That
is excellent for an 18-year-old pond, which has never had a complete water
change”. This testimonial was made to let the hobbyist know that a complete
teardown (like some system require) of the system has never been executed, in
other words; a 100% of its water mass has never been replaced at one time or
another.
I also say in my iTunes
Book: “Now let us take for example the Anoxic Filtration System. In
the 18 years that I have been experimenting/studying and researching this
system, I only clean the filter system twice a year, once in March and another
time in late autumn at the end of October. This is the only water change my
pond has ever received in 18 years.” Some hobbyists that use this system can
and have done the same thing as myself, and some have done even better using
this system than I. All I am telling you is what “I have done under controlled
conditions in an experimental pond.” I just give you the results that the
Beta-testing pond and I have had. After all, I do not know your animals feeding
habits, stocking levels, geographical location, or your pond husbandry.
Nevertheless, I do say in my iTunes Book to clean the filtration system out at
lest twice a year. No filtration manufacture can predetermine what a person
will do with their filtration systems 100% of the time, and neither can I for
that matter.
In fact in my iTunes Book,
I give an example of one hobbyist that only does two water changes a year and
has crystal clear water that will impress the most hardcore hobbyist into
acquiescence. However, he does not “over feed” his Koi nor does he “overstock”
his pond. The relationship between filter and animal load is in equilibrium with
each other. Not all hobbyist fall into this category.
I also must take 100% of
the blameworthiness for my iTunes Book not coming across very clearly to the
hobbyist and for that, I make an apology.
Kevin
E-mail:
G Day Dr Kevin
I am from Sydney Australia and this
year I acquired you Anoxic filtration system from a club member who was getting
out of Koi due to ill health.
I placed the baskets in my breeding
set up which normally we have high ammonia levels and have to do lots of
water changes ,this year no water changes and the fry grew quicker and I was
able to double the amount of fish I spawned so am very impressed I would like
to acquire your video ( Cd-Book) so as I can share the knowledge, could you
please let me know what the cost are including the shipping and if you are down
this nick of the woods please let me know yes we are all Koi mad here in
Australia.
Regards Gerard,
Chairperson of the northern branch in Australia
Here is my original article on Pollutant Equilibrium (or PE for short). This article definitely encompasses the
aquarium hobbyist too.
Q:
We own a
three thousand-gallon pond and every month we do a 10% water change. We have
talked to other hobbyists and some say they do a water change and others say
they do not change any of the pond water. My question is: When changing water
in a pond how much and how often should it be changed, if at all?
A:
Nature’s
waters are abundant in biological materials, ranging from microscopic organisms
too large aquatic plants and animals including fish. The presence of plants and
animals in the aquatic environment means that there are also organic and
inorganic byproducts being mineralize from solid organic materials from living
or dead tissue. These breakdown products include humic acid, oils, waxes,
assorted hydrocarbons, and fatty acids “all invisible residues that affect
water quality. Although, it does not matter whether it is a lake, river, or the
vast oceans, the waste generated by fish, our aquatic animals and plants do not
accumulate to any significant extent the sheer volume of water of the habitat
is diluting it. The pollution concentrations are also eradicated and diluted
largely in cases such as rivers and natural pond waters, since freshwater is
renewing it constantly through the intersection of topography, being stream-fed
with freshwater, rainwater, and meltwater from ice or snow.
However, the typical ornamental pond
operates as a closed recirculation system, with the same water remaining in the
pond for weeks or months at a time, even if it rains frequently this will make
an insignificant difference. In this situation water quality is always a
problem because as time passes various physical, chemical, and biological
processes working in and around the pond alters the initial tabula rasa
characteristics of the water.
In an enclosed ecosystem such
as our ponds, a void of an overabundance of plants and ion nutrient users, most
hobbyists think they can make their ponds oligotrophic in nature, but this is
much harder than one thinks to achieve. Because; most of the time filtration
systems are inadequate at the removal of pollutants generated by the
inhabitants and clean highly oxygenated water is dependent upon the filtration
systems capabilities and the amount of water that is being exchanged by the
hobbyists periodically.
There is little argument
whether a periodic partial water change is necessary to maintain a healthy pond
that fish can live in without undue stress. I also think that all hobbyists
would agree that all ponds would benefit from more frequent water changes and
generally this would be “the more frequent the better.” However, how much water
should be renewed and how often should such changes take place are often a
matter of discrepancy. Finding unambiguous answers to these questions in
hobbyists’ books and monthly periodicals may become a crapshoot at best. Too
many hobbyists do not understand the mathematical equations used to determine
whether water changes would become beneficial or redundant in an enclosed
ecosystem such as our ponds.
One thing hobbyists must understand
is the idiom Pollutant Equilibrium (or PE for short). Pollutant
Equilibrium means that the amount of pollutants that are being produced by the
animals, plants, filter and the amount the water that is exchanged from
periodic water changes will reach what is called a steady state or constant
state. This means when a steady income of pollutants are being produced at a
given rate and water is being exchanged at a given rate that everything will
remain on an equilibrium with each other and nothing will increase or decrease
over a given time. If pollutants overshadow the amount of water being exchanged
then the amount of pollutants will increase over time to toxic levels even
though a constant amount of water is being replaced. This arises due to
inadequate filtration systems the hobbyist thought would work for their fish
load.
For example; let’s say you have a
pond, for the sake of argument will say this pond is 3000 gallons, that
is producing 8-ppm (ppm = parts per million) of nitrogen (NO3) every month,
this now becomes a constant. The hobbyist now wishes to reduce this
nitrogen compound by doing a water change on a monthly basis. If the hobbyists
were to do a 50 percent water change, this now would halve the amount of
pollutants to 4-ppm (0+8)-50%= 4). However, do not forget that every month the
NO3 levels will begin again to elevate another 8-ppm. In addition, you must
include the NO3 compounds that were remaining from the last water change. The
next month will make the pollutant level elevate to 12-ppm before a water
change (4+8)-50%=6). The next month after that it will elevate to 14-ppm
(6+8)-50%=7) and so on in their pond. It would now take eight months before a
PE is then reached.
Then every month afterwards, the
Nitrogen compounds being produced, and the amount of water being exchange would
be in equilibrium with each other, and would remain at a constant 15.9-ppm NO3
levels or a steady state. As you can see the hobbyists even after conducting a
50 percent water change of 1500-gallons, may still run into problems with
cyanobacteria and algae buildup, as green water in the pond. Because their
nitrogen compounds have now exceeded the safety margin of keeping nitrates
below the 15-ppm limit every month before a water change is executed.
If the same hobbyists were only
to do 20% water change every month, it would take over sixteen months before a
PE would be reached of 39.0-ppm NO3 levels. If the water changes were only 10%,
calculation similar to those used above, would show the ensuring situation
deteriorating even further, with the pollutants stabilizing at 20 times the
amount generated from one water change to the next. Besides, the PE values
differing with different extent of water being change the time it takes for PE
to be reached also differs. In reality, doing a water change of anything less
than 40 percent would be useless in anybody’s pond. The consequences of
increasing or decreasing the frequency of water changes or the volume of water
replaced on each occasion would only be anyone’s guess. Do to the fact the
hobbyists not knowing the exact aleatory nature of the biomass and how much
pollutant matter is being generated in a single day of the pond
existence.
Therefore, with the information that
we now know regarding the buildup of pollutants and routine partial water
changes we can conclude the following. Starting with pure unpolluted water,
pollutants in the pond will progressively increase with time, even as partial
water changes continue at regular intervals. However, this increased does not
continue unabated but stabilize as it reaches PE. The greater the proportion
and the shorter the régime-time between each renew water change the lower the
PE would be and the shorter the time it will take the PE goal to be reached. As
you can see, winning the battle against pollutants in an enclosed biotope such
as our ponds seems almost to be futile1. This is because the amount of nitrogenous wastes produced is
many times greater than the pond’s natural capacity to absorb it.
However, one of the biggest
weapons we have in our arsenal which is in our favor is a well-designed
filtration system, which we can implement in the battle against the pollutants.
Now we come down to the one big problem that all hobbyists are faced with and
that is “the well-designed filtration system.” Since this is easier said than
done the hobbyists are left with no other alternative than to do partial water
changes in their pond.
Even with the Anoxic Filtration
System, as good as it is still needs to have at least two partial water changes
made each year. Generally, the greater proportion of water that is changed
during the filter cleanout the lower the stabilizing pollutant level in the
pond would be. Because of this filtration systems capability, the Pollutant
Equilibrium levels are reached within a short time-span of weeks instead of
months, without all the frustrating water changes and the cost of doing them.
From what we have learned, the hobbyist that does 10 percent water changes
would hardly be worth the endeavor or their valuable time.
1: The fact is that the actual
ammonia, nitrite, and nitrate levels in a fully recirculating biotope such as
our ponds that requires supplementary biological filtration is never zero “even
if the filter design ensures 100 percent inorganic compound removal
effectiveness. There is always some trace amount of these compounds in bulk
water because the fish are constantly adding ammonia (fish continuously excrete
ammonia through their gills, as well as through diluted urine) and other
organic compounds to the water body proper. The filter can only remove ammonia
and nitrites from that small portion of the pond water that is moving through
it at any given time. So, even as one portion of the pond water is being cleansed of these compounds, another part is being polluted at
the same time.
