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Fluidized bed filters


kiwiplymouth

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I just bought this brand new on trademe for $14 :D

The blurb on the net says it is suitable for a 1000L tank.

I plan to add it to one of my 5 foot african tanks that currently only being filtered by one 1400lph cannister filter.

I plan to over stock this tank so will need the extra filtration.

I plan to connect this to the outlet of my canister filter or would it be better if I used a seperate pump.

The blurb on the net says connection to a canister filter is fine but I was wondering if anyone else has used these filters and if so how did you set them up.

115354794_full.jpg

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Generally you'd connect it to some kind of pump and adjust the water flow until all the media is kept suspended, but not blown out of the filter.

They've always seemed a bit gimmicky to me, or at least more trouble than they're worth.

Well the price was right so I had to give it a try.

Who knows, I might learn something :D

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you got that bloody cheap :o i would run it from a separate pump so you can adjust the flow rate as needed so you're not blowing the dand out of it they can awesome biological capacity so just watch the surface has enough turbulence to add extra oxygen as the bacteria will consume a lot of o2

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The basis that they work on is that the surface area of the sand is HUGE! therefore allows a massive amount of bacteria to grow on it.

The problem is that some peope reckon that the turbulence and constant collision of the sand particles means that bacteria can't get a chance to grow fully. some argue that the constant renewal acts as an advantage.

try it out, tell us what you find. Make sure to check the temperature of the outgoing too, they apparently generate a decent amount of heat due to friction...

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The basis that they work on is that the surface area of the sand is HUGE! therefore allows a massive amount of bacteria to grow on it.

I'm not convinced that surface area is the limiting factor to bacteria growth in most tanks though, even heavily stocked ones. If that were the case there would be all kinds of tanks out there with continuously rising ammonia and nitrite levels, but as it is most tanks have undetectable levels leading me to believe that food supply is the limiting factor.

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I'm not convinced that surface area is the limiting factor to bacteria growth in most tanks though, even heavily stocked ones. If that were the case there would be all kinds of tanks out there with continuously rising ammonia and nitrite levels, but as it is most tanks have undetectable levels leading me to believe that food supply is the limiting factor.

Why is Mark doing this then?

viewtopic.php?f=28&t=43132

Surely he isn't going to all this effort just for mechanical filtration.

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i am not running any substrate in the tank

as gravel vac to 1,2 m and 3 sq metres of it will be a chore

just a personal opinion but i believe substrate, the tank walls and any media all provide a serface for bacteria to live on

a balancing act is created between the bio load and bacteria levels

the idea behind the semi tower construction is keepimg a good flow through the media of oxygenated water, it is dropping from 2 metres and delivered back by 2 spraybars

filter wool to take out the big crud

and sediment flowing through the media

with a drain at bottom to clear detritus

basically just a bigger version of a canister filter

i ran a 4 foot local marine tank with 1" of shell substrate, 6 airstones, a berlin skimmer and weekly water changes for 4 years

i have a couple of those fluidised bed filters sitting in the shed, got them when they first came on the market in nz

used one on an existing local marine tank, i think they take a short while for bacteria to build up in the sand

as leg before wicket (cricketman) has said they generate a bit of heat

aand i think you may need a prefilter to stop any food getting into it

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I'm not convinced that surface area is the limiting factor to bacteria growth in most tanks though, even heavily stocked ones. If that were the case there would be all kinds of tanks out there with continuously rising ammonia and nitrite levels, but as it is most tanks have undetectable levels leading me to believe that food supply is the limiting factor.

surface area is not the only factor influencing bacteria growth in an enclosed system

as you have said once tank is established, same fish, plants and feeding regime then a balance is also achieved between bacteria and bio load

temp drops or rises, over feeding or extra fish in tank will change the balance

if it is changed too dramatically then a crash can be precipitated

until the balance is achieved frequent water changes work to water down ammonia etc. levels

our large malawi tank has a large wet/dry sump on it with a large flow through

i am also a minimal feeder of my fish as over feeding can create all sorts of unseen problems

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I'm not convinced that surface area is the limiting factor to bacteria growth in most tanks though, even heavily stocked ones. If that were the case there would be all kinds of tanks out there with continuously rising ammonia and nitrite levels, but as it is most tanks have undetectable levels leading me to believe that food supply is the limiting factor.

The basis of alot of media is to provide a high flow through to deliver the bacteria the nitrogenous wastes, sa well as high O2 levels (without which there is teh formation of anoxic / anaerobic bacteria which use sulphur to respire and cause amounts of Sulphides and sulphites which are completely toxic to fish) and to provide a large surface area within a small confine (IE. to try and cram as much bacteria into a smallest dimensions possible.)

This is the factor that many manufacturers of media rely on (bio balls, for a well known example)

Now this surface area and aggitation is seen in the extreme with the fluidised bed filter.

The fact that Kelly Tarltons and a number of other major aquariums around the world use them I think stands testement to thier effectiveness.

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It doesn't matter how a filter is constructed or how it runs it is the food that mainly controls the bacterial numbers. The bacterial numbers will form a balance with the food available.

If the food decreases or increases so will the bacterial numbers. The filter is just a place for the bugs to hang out.

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It doesn't matter how a filter is constructed or how it runs it is the food that mainly controls the bacterial numbers. The bacterial numbers will form a balance with the food available.

If the food decreases or increases so will the bacterial numbers. The filter is just a place for the bugs to hang out.

And, if you can maximise the surface area:dimensional area, the more stock you can house within the tank, for a smaller dimensional filter, which takes up less space. so therefore, in a situation where space is at a premium, or perhaps you want above average stocking, a fluidised bed filter provides the best (argueable between scientific realms of thought) SA to 3 dimensional space

Do you see what this means in terms of teh sand filters being really quite small compared to a canister to provide the same SA for the bacteria to "hang out" in...

Also instead of food which might confuse the newbies, lets get techical and call it nitrogenous waste that the bacteria feed on...

I don't know if I can make my point any clearer.

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It doesn't matter how a filter is constructed or how it runs it is the food that mainly controls the bacterial numbers. The bacterial numbers will form a balance with the food available.

If the food decreases or increases so will the bacterial numbers. The filter is just a place for the bugs to hang out.

Most experienced fish keepers would recommend the use of 2 canister filters in a 5 foot tank.

Are you saying that the second canister filter is of no real benefit for biological filtration and its sole purpose is for extra mechanical filtration?

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2 canisters or 1 big one on a 5 footer

i think the point being reiterated is that no matter how much surface area for bacteria to live on they are still reliant on a food source to keep their numbers up

so a larger number of bacteria needs a larger food source and larger space to live on

you can't have one without the other

love and marriage

horse and carriage

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The bacteria are feeding on (bacterial) food not nitrogenous waste. The nitrogen is still there in the form of nitrite or nitrate so they are converting nitrogen compounds while feeding on bacterial food ----whatever that might be.

Food is the main limiting factor. If they have a high bio load from heaps of fish they will multiply to use it up. If you have massive filters and a small bio load the filter will only contain a fraction of its bacterial capacity whatever filter you have. With a big filter the bacteria can multiply to the max without any housing or overcrowding problems.

With all of this you can still get to artificially high stocking rates and the system will realy crash big time if there is a power failure or something goes wrong with the filter.

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An extract from http://www.aquariumpros.com/articles/bi ... ypes.shtml

If properly designed and built tall enough, they have the ability to cultivate not only aerobic nitrifying bacteria, but also facultative anaerobic denitrifying bacteria. This means they may have the capability to remove not only ammonia and nitrite, but also nitrates.

So how tall is tall enough ? :wink:

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If your filter is chocker full of aerobic nitrifying bacteria then it must have a good supply of oxygen because those bugs need it. Facultative bacteria can live with or without oxygen but facultative anaerobes can live with oxygen but will only carry out the removal of nitrate in the absence of oxygen.

It would be a pretty clever filter to be aerobic at one end and anaerobic at the other and stay that way.

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Another quote from the above site

The water at the bottom of the filter is fresh and high in dissolved oxygen, so aerobic bacteria cultivate in the bottom half of the sand bed, and remove ammonia and nitrite, using up oxygen in the process. In taller fluidized-bed filters, enough aerobic bacteria cultivate in the bottom half so that as water flows past them, they remove most of the oxygen from the water, so facultative anaerobic bacteria cultivate in the top half of the sand bed where they remove nitrates. Not all fluidized-bed filters are tall enough to promote anaerobic denitrifying bacteria, but most are very efficient at cultivating beneficial aerobic bacteria.
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