Filtration: Scaling Ponds to Aquariums

[David]

For reference, I have posted here before regarding the design of a
large outdoor tropical aquarium, integrated with a tropical water
garden.

The overall design continues, but I am struggling with the filtration.
Specifically, the issue of water turnover rates.

I have a much better understanding of koi pond filtration than of
aquarium filtration. I can design an acceptable koi pond filteration
system, and I am hoping that I should be able to scale such a design
to work effectively for the subject aquarium. But the rules of thumb
for turnover rates are different. Typically, the water volume of a
koi pond is turned over every one or two hours. However, I see
requirements for aquarium turnover rates of 4-6 times per hour. At a
minimum 3x per hour. NetMax says 2x per hour minimum for a
well-planted tank. So you see my dilemma -- one of the most basic
filter design parameters is flow rate.

I realize of course that the differences between a typical outdoor koi
pond, and a typical indoor aquarium, are so numerous that it would be
silly to even begin to list them. But standing back from the problem,
the requirements should be the same, shouldn't they(?): to provide
adequate mechanical, biological, and if necessary, chemical
filtration. (And of course aeration and circulation.)

Intuitively, (I haven't researched this enough to back it up), koi
ponds normally have a higher bio-load than aquariums.

So, bottom line, I think my present question boils down to, why do
aquariums require a turnover rate of four to ten times greater than
that for koi ponds?

Thank you very much for any thoughts,
David

[Richard Sexton]

>So, bottom line, I think my present question boils down to, why do
>aquariums require a turnover rate of four to ten times greater than
>that for koi ponds?

Because of the smaller volume of water involved. My rule of thumb is
if you can see some sort of decent water current halfway across the longest
axis, it's fine.


--
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Richard Sexton | Mercedes stuff: http://mbz.org
1970 280SE, 72 280SE | Home page: http://rs79.vrx.net
633CSi 250SE/C 300SD | http://aquaria.net http://killi.net

[~Roy~]

I have had perfectly good results with keeping tropicals in various
preforms and water gardens outside when the temps get above the
minimum, and thats about 8 to 9 months out of the year the tropicals
stay outside. I have filtration suitable for koi/goldies. I really do
not see why tropoca;s kept outside would require any higher of a
turnover than what is used for koi, as koi and goldies are messy and
pr0duce a lot more junk than most tropicals do. I can see needing a
higher turnover in a typical tank due to "maintaining crystal clear
water, and its a much smaller system as compared to larger outdoor
features so its necessary to turn the water more....Filtration on koi
ponds are generally much much larger than tyoically found on indoor
tanks, mainly due to bio loads......

On Tue, 21 Feb 2006 06:07:04 -0700, David >
wrote:
>><>For reference, I have posted here before regarding the design of a
>><>large outdoor tropical aquarium, integrated with a tropical water
>><>garden.
>><>
>><>The overall design continues, but I am struggling with the filtration.
>><>Specifically, the issue of water turnover rates.
>><>
>><>I have a much better understanding of koi pond filtration than of
>><>aquarium filtration. I can design an acceptable koi pond filteration
>><>system, and I am hoping that I should be able to scale such a design
>><>to work effectively for the subject aquarium. But the rules of thumb
>><>for turnover rates are different. Typically, the water volume of a
>><>koi pond is turned over every one or two hours. However, I see
>><>requirements for aquarium turnover rates of 4-6 times per hour. At a
>><>minimum 3x per hour. NetMax says 2x per hour minimum for a
>><>well-planted tank. So you see my dilemma -- one of the most basic
>><>filter design parameters is flow rate.
>><>
>><>I realize of course that the differences between a typical outdoor koi
>><>pond, and a typical indoor aquarium, are so numerous that it would be
>><>silly to even begin to list them. But standing back from the problem,
>><>the requirements should be the same, shouldn't they(?): to provide
>><>adequate mechanical, biological, and if necessary, chemical
>><>filtration. (And of course aeration and circulation.)
>><>
>><>Intuitively, (I haven't researched this enough to back it up), koi
>><>ponds normally have a higher bio-load than aquariums.
>><>
>><>So, bottom line, I think my present question boils down to, why do
>><>aquariums require a turnover rate of four to ten times greater than
>><>that for koi ponds?
>><>
>><>Thank you very much for any thoughts,
>><>David

--
\\\|///
( @ @ )
-----------oOOo(_)oOOo---------------


oooO
---------( )----Oooo----------------
\ ( ( )
\_) ) /
(_/
The original frugal ponder ! Koi-ahoi mates....

[Marco Schwarz]

Hi..

> well-planted tank. So you see my dilemma -- one of the
> most basic filter design parameters is flow rate.

Yes and no. One will have to regard the fish needs, too.
Lake fish for example don't need or prefer a high water
flow-rate.

How big is your aquarium?

> So, bottom line, I think my present question boils down
> to, why do aquariums require a turnover rate of four to
> ten times greater than that for koi ponds?

They don't.

--
cu
Marco

[NetMax]

"David" > wrote in message
...
> For reference, I have posted here before regarding the design of a
> large outdoor tropical aquarium, integrated with a tropical water
> garden.
>
> The overall design continues, but I am struggling with the filtration.
> Specifically, the issue of water turnover rates.
>
> I have a much better understanding of koi pond filtration than of
> aquarium filtration. I can design an acceptable koi pond filteration
> system, and I am hoping that I should be able to scale such a design
> to work effectively for the subject aquarium. But the rules of thumb
> for turnover rates are different. Typically, the water volume of a
> koi pond is turned over every one or two hours. However, I see
> requirements for aquarium turnover rates of 4-6 times per hour. At a
> minimum 3x per hour. NetMax says 2x per hour minimum for a
> well-planted tank. So you see my dilemma -- one of the most basic
> filter design parameters is flow rate.
>
> I realize of course that the differences between a typical outdoor koi
> pond, and a typical indoor aquarium, are so numerous that it would be
> silly to even begin to list them. But standing back from the problem,
> the requirements should be the same, shouldn't they(?): to provide
> adequate mechanical, biological, and if necessary, chemical
> filtration. (And of course aeration and circulation.)
>
> Intuitively, (I haven't researched this enough to back it up), koi
> ponds normally have a higher bio-load than aquariums.
>
> So, bottom line, I think my present question boils down to, why do
> aquariums require a turnover rate of four to ten times greater than
> that for koi ponds?
>
> Thank you very much for any thoughts,
> David

Can you post more specifics (ie: fish types, quantity, depth of water,
difference between average ambient temperature and water temperature, that
sort of stuff).

There are several factors coming into play. Biologically, a pond has a lot
more diversity and surface area prior to adding filtration. Mechanically,
the needs vary according to the amount of plant life being supported. From
the view of turbulence, (the angle you're now investigating) depth is a
factor (O2 levels in the deep end) which affects fish types (many catfish
like higher O2 levels), as well as thermal layering (and I can't begin to
know which fish would be more vulnerable to this). The pond guideline of
0.5X also has a lot to do with practicality (20,000gph pumps get a little
far from the average person's budget). There are many factors. Home
aquariums can operate on zero filtration under certain conditions, as can
ponds.

To answer your question (jmo now), i) home aquariums have less biodiversity
and are more dependant on their filtration, ii) aquariums achieve higher
bio-loads and iii) the water quality expectations are higher for aquariums.
Of course, exceptions exist to every point listed ;~).

I'm no expert, but I can probably help you ask some good questions :-).
--
www.NetMax.tk

[Bill Stock]

"NetMax" > wrote in message
...
> "David" > wrote in message
> ...
>> For reference, I have posted here before regarding the design of a
>> large outdoor tropical aquarium, integrated with a tropical water
>> garden.
>>
>> The overall design continues, but I am struggling with the filtration.
>> Specifically, the issue of water turnover rates.
>>
>> I have a much better understanding of koi pond filtration than of
>> aquarium filtration. I can design an acceptable koi pond filteration
>> system, and I am hoping that I should be able to scale such a design
>> to work effectively for the subject aquarium. But the rules of thumb
>> for turnover rates are different. Typically, the water volume of a
>> koi pond is turned over every one or two hours. However, I see
>> requirements for aquarium turnover rates of 4-6 times per hour. At a
>> minimum 3x per hour. NetMax says 2x per hour minimum for a
>> well-planted tank. So you see my dilemma -- one of the most basic
>> filter design parameters is flow rate.
>>
>> I realize of course that the differences between a typical outdoor koi
>> pond, and a typical indoor aquarium, are so numerous that it would be
>> silly to even begin to list them. But standing back from the problem,
>> the requirements should be the same, shouldn't they(?): to provide
>> adequate mechanical, biological, and if necessary, chemical
>> filtration. (And of course aeration and circulation.)
>>
>> Intuitively, (I haven't researched this enough to back it up), koi
>> ponds normally have a higher bio-load than aquariums.
>>
>> So, bottom line, I think my present question boils down to, why do
>> aquariums require a turnover rate of four to ten times greater than
>> that for koi ponds?
>>
>> Thank you very much for any thoughts,
>> David
>
> Can you post more specifics (ie: fish types, quantity, depth of water,
> difference between average ambient temperature and water temperature, that
> sort of stuff).
>
> There are several factors coming into play. Biologically, a pond has a
> lot more diversity and surface area prior to adding filtration.
> Mechanically, the needs vary according to the amount of plant life being
> supported. From the view of turbulence, (the angle you're now
> investigating) depth is a factor (O2 levels in the deep end) which affects
> fish types (many catfish like higher O2 levels), as well as thermal
> layering (and I can't begin to know which fish would be more vulnerable to
> this). The pond guideline of 0.5X also has a lot to do with practicality
> (20,000gph pumps get a little far from the average person's budget).
> There are many factors. Home aquariums can operate on zero filtration
> under certain conditions, as can ponds.
>
> To answer your question (jmo now), i) home aquariums have less
> biodiversity and are more dependant on their filtration, ii) aquariums
> achieve higher bio-loads and iii) the water quality expectations are
> higher for aquariums. Of course, exceptions exist to every point listed
> ;~).
>
> I'm no expert, but I can probably help you ask some good questions :-).

He's a consultant, can't you tell. :)



I can't really offer any scientific evidence, just my own anecdotes.

My outdoor pond was 500 gallons, with 9 smallish (3") Goldfish and umpteen
fry. It was heavily planted/algaed with a crappy sponge
mechanical/biofilter. It does collect a fair amount of muck each year,
leaves, cherries, fish poop, bird droppings, etc. I usually have to add
Nitrates for the plants.

I now have the same fish in an indoor pond with about 250 gallons of water.
I ran it for about two months no filter at all, just some aeration from the
pump. I have since connected the filter from the outdoor pond, but I really
don't think it's necessary. I'm having to add 2 Tbsps of Nitrates (KNO3)
per week to keep the plants healthy. The plants appear to be providing more
than enough filtration. The other factor is the low bioload compared to the
typical aquarium.

[NetMax]

interspersed below..

"David" > wrote in message
...
> On Tue, 21 Feb 2006 06:07:04 -0700, David >
> wrote:
>
>>For reference, I have posted here before regarding the design of a
>>large outdoor tropical aquarium, integrated with a tropical water
>>garden.
>>
>>The overall design continues, but I am struggling with the filtration.
>>Specifically, the issue of water turnover rates.
>>
>>I have a much better understanding of koi pond filtration than of
>>aquarium filtration. I can design an acceptable koi pond filteration
>>system, and I am hoping that I should be able to scale such a design
>>to work effectively for the subject aquarium. But the rules of thumb
>>for turnover rates are different. Typically, the water volume of a
>>koi pond is turned over every one or two hours. However, I see
>>requirements for aquarium turnover rates of 4-6 times per hour. At a
>>minimum 3x per hour. NetMax says 2x per hour minimum for a
>>well-planted tank. So you see my dilemma -- one of the most basic
>>filter design parameters is flow rate.
>>
>>I realize of course that the differences between a typical outdoor koi
>>pond, and a typical indoor aquarium, are so numerous that it would be
>>silly to even begin to list them. But standing back from the problem,
>>the requirements should be the same, shouldn't they(?): to provide
>>adequate mechanical, biological, and if necessary, chemical
>>filtration. (And of course aeration and circulation.)
>>
>>Intuitively, (I haven't researched this enough to back it up), koi
>>ponds normally have a higher bio-load than aquariums.
>>
>>So, bottom line, I think my present question boils down to, why do
>>aquariums require a turnover rate of four to ten times greater than
>>that for koi ponds?
>>
>>Thank you very much for any thoughts,
>>David
>
> Thank you all for your most welcome responses! From them, I am
> feeling more comfortable about this now.
>
> You have asked for some more details, which I will try to provide.
> There is so much to say that I really wish I could just post a design,
> but I'm not there yet. Maybe you all will be so kind to critique it
> when I get there...?
>
> First, I am planning on actually three aquariums, plumbed in parallel,
> (to avoid pumping all the detritus from one into the next). Each is
> looking like it will be around 450 gallons. The dimensions are
> looking like about 36" depth by 68" length by 42" width -- but
> everything is still subject to change.

You could do all that with a standard swimming pool pump and sand filter.

> Each tank will have an air-diffuser bottom drain and a surface
> skimmer. These will feed, from all tanks, into a vortex settlement
> chamber. From there the flow will be to mechanical filtration, with
> brushes and (matala fiber(?)) mats. From there on to a moving bed
> biological filter, using Kaldnes K1 media. And from there to the
> pump, to circulate back to the tank input manifold. Somewhere in all
> this will be a valve-controllable exchange with the water garden
> circuit -- which will be heavily planted, to serve as additional
> bio-filtration. (Oh, I intend for the tanks to be well-planted as
> well.)

Keep in mind that this is a serial system, so your vulnerability comes
from the weakest stage, and the frequency (and probability) of problems
increases as a function of the number of stages the water goes through.
Complexity bites. Add to that your plans for lots of plants (moving
restrictions to filtration systems), and you should play close attention
to screening out large organic matter with overflows.

> The latter leads me to your response, Bill, regarding having to add
> additional fertilizer because there might actually be *too much*
> veggie filtration. (I am worried about this, and that's why I want to
> be able to control the exchange with the water garden.)

If the point is to have the plants filter, then don't worry about this.
Their growth restraint (control) will be the periodic unavailability of
certain elements (ie: NO3).

> Regarding your questions, NetMax, I cannot yet be specific about the
> fish types -- but there are a *seemingly infinte!* variety available
> in the Bangkok live fish market, and I will be trying many of them as
> continue to learn.

The more you narrow this down, the more focused your design can become.
It's a lot easier to design filtration and water movement around large
fish, than small fish.

> As to the site temperatures, the statistics run from 11.3*C (52*F) to
> 39.7*C (103.5*F). The former are during the night in the coldest part
> of "winter" and don't last very long. I am planning for most of the
> aquarium circuit to be "in the ground", so that will hopefully provide
> a buffer on temperature fluctuations.

That's a nice range. Depending on your surface area, and exposure to sun
and wind, you will probably track the daily average, minus a few degrees,
with some lag time (2-4 days). I would carefully monitor the
temperatures for the first few months to have a feel for how the system
reacts. You can divert some water through your garden to increase the
temperature, or divert it to water elements to cool it (ie: divert to
waterfalls or fountains overnight to cool down)

> The water parameters I am unable to say anything much about at all
> yet, except that I doubt that it would be high pH.

Given the amount of organic matter, your buffer will not be based on
calcium carbonates ;~) but your local fish will be accustomed to low pH
anyways.

> I'm sorry for being so long-winded -- that really isn't my nature.

It's a big project :o)

> But, given what I have said, if you kind folks could give me your
> thoughts on what would be a best first-guess flow rate through each
> tank, I would be most obliged. (BTW, I do intend to have the tank
> inlets at several levels, to improve circulation.)

How many gph (or gpm?) are standard pool pumps? I think I had one full
open on a 1500g set-up. I know I had one throttled back on an 800g
set-up. Just have to remember to backwash every day, 15 seconds. The
real trick will be in the pre-screens and the balancing between the 3
tanks, but this is just an interesting diversion before selecting the
flora and fauna :o)
--
www.NetMax.tk

> Best regards,
> David

[NetMax]

"David" > wrote in message
...
> On Wed, 22 Feb 2006 23:26:06 -0500, "NetMax"
> > wrote:
<snip>
> That is a worry for me: Once a tank is set up, can I be sure
> that I will be able to find a compatible and interesting collection to
> live together in it??

In that size body of water, with plants, hiding spaces and your natural
conditions (water & temperature) you may be hard-pressed to keep the fish
from spawning to capacity.

>>> As to the site temperatures, the statistics run from 11.3*C (52*F) to
>>> 39.7*C (103.5*F). The former are during the night in the coldest part
>>> of "winter" and don't last very long. I am planning for most of the
>>> aquarium circuit to be "in the ground", so that will hopefully provide
>>> a buffer on temperature fluctuations.
>>
>>That's a nice range. Depending on your surface area, and exposure to sun
>>and wind, you will probably track the daily average, minus a few degrees,
>>with some lag time (2-4 days). I would carefully monitor the
>>temperatures for the first few months to have a feel for how the system
>>reacts. You can divert some water through your garden to increase the
>>temperature, or divert it to water elements to cool it (ie: divert to
>>waterfalls or fountains overnight to cool down)
> All good points -- will do...
>>
>>> The water parameters I am unable to say anything much about at all
>>> yet, except that I doubt that it would be high pH.
>>
>>Given the amount of organic matter, your buffer will not be based on
>>calcium carbonates ;~) but your local fish will be accustomed to low pH
>>anyways.
> Can you please elaborate on this -- what will my buffer be based upon?

I cannot elaborate as I have no experience with it. My familiarity is with
calcium-based alkalinity, either using well water, or using municipal river
water which is buffered up with calcium carbonates (minerals, coral, baking
soda etc). There are other buffers. When water lacks buffer (ie: DI, RO,
rainwater etc), it is pH unstable, however, it's my understanding that
nature usually (not always) provides other natural buffers in sof****er
environments.

>>> I'm sorry for being so long-winded -- that really isn't my nature.
>>
>>It's a big project :o)
>>
>>> But, given what I have said, if you kind folks could give me your
>>> thoughts on what would be a best first-guess flow rate through each
>>> tank, I would be most obliged. (BTW, I do intend to have the tank
>>> inlets at several levels, to improve circulation.)
>>
>>How many gph (or gpm?) are standard pool pumps? I think I had one full
>>open on a 1500g set-up. I know I had one throttled back on an 800g
>>set-up. Just have to remember to backwash every day, 15 seconds. The
>>real trick will be in the pre-screens and the balancing between the 3
>>tanks, but this is just an interesting diversion before selecting the
>>flora and fauna :o)
>
> I promise to finish after this, <g>: Suppose, just suppose, someone
> were to give you a 450 gal tank, and with it came all the external
> filtration you would ever need, (I am hoping that I will be able to
> provide that); then, would it be realistically possible for you to
> estimate what should be the maximum GPM that should be expected to
> ever be needed through that tank? (I assume this would imply the
> maximum fish-load and also no plants.) With that GPM estimate, I can
> then size the pump and filtration system. (And can, of course, then
> scale back the GPM if later required.)

A Fluval FX5, 924gph would probably do a 450g with a normal fish load.
There isn't really a 'max' fish load (as long as they can breathe ;~). You
could put 4,000 feeder goldfish in a 450g, but you would need to size up the
filtration accordingly. The biological component of filtration is a
function of bio-mass and not gallons of water. When we try to relate gph to
gallons, the typical range is x1 to x5 volumes per hour (or 450 to 2250gph
for a 450g tank), where x1 is typically lower fish load and high quality
small particle filtration (ie: canisters), and x5 is for 'sloppier'
filtration (HOB powerfilters). Ponds tend to be in the x.03 to x1 range
(with most targeting x0.5), but ponds typically have a much higher
biological processing power, through surface area and plants.
--
www.NetMax.tk

> I've consumed far too much of your time. Thank you so much!
> Best regards,
> David