Fluidised Bed Filtration

[Gigitt]

Ok I have a few questions about Fluidized Bed Filtration. (Google Search Here (Search in AUS only)

If you dont know what I'm talking about ... then read this link (I hope this link is OK to post here)

btw: I have read quite a few pages on this, and they all seem to Quote/Say the same as this link above.

The Benifits look really good for such a simple device and the price is right (no pun intended)

Anyway my Questions:

1) The Article does say that a Fluidised Bed Filtration will use more oxygen in the water due to the bacteria doing its thing and conversly expell Carbon Dioxide (CO2). This means that a well planted tank will benifit from the extra CO2 generated from the Fluidised Bed Filtration... but will it be too much CO2 as there is no controling what bactieria expell?

2) This is cheaper solution to a CO2 injector system (which should be switched off at night), but if CO2 is gerated 24/7 with a Fluidised Bed Filter and plants do not absorb CO2 without light... is it still OK to use or will the generation of CO2 and the delpetion of O2 for the fish be too much? (I suppose using less Sand media will adjust the levels) (I did run a DIY CO2 generator without any problems for about 3 months - and it was 24/7 (2ltr Coke Bomb with a underwater CO2 capture housing so CO2 could be absorbed and not just buble away to the surface) )

3) Small systems are available quite cheaply and support up to 1000lt tank system/s. Is a 4ft tank too little have a Fluidised Bed Filtration systems like this? (again... I suppose using less Sand media will adjust the bacteria O2/CO2 levels)

4) Does the Bacteria population change with the amount of waste in the tank if there is too much media for them to live on? If yes then you will not need to adjust the levels of Sand media in the Fluidised Bed Filter.

5) Or is there never too much media for bacteria to grow for biological filtration?

6) Does anyone run a Fluidised Bed Filter?

7) How well does it work for you?

8) Has it reduced your Tank filter maintenance and water changes?

I would really some of your thoughts on this.

I think this has potential in any Planted Aquarium Tank.

[chuin]

Giggit

I don't know the technical details of how a FBF works - in my experience, it just works! I run a FBF in my 500lt tank -as well as a cannister filter back up - and it has kept the tank in great condition.

Maintenance - very little, just keep checking the fluidisation level. I had 4 weeks holiday recently and while I had a house sitter who fed the fish, I found out that they did not do any water changes! All fish survived and water conditions were pretty good. (not that I would recommend this as a constant practice).

You're right about the price, it is a cheap filter system and easy to set up. Just plug a pump to it with a filter and you're away. If you do set one up, the only tips I have (again my experience only) is to minimise distance between pump and FBF (this lets you have a smaller and cheaper pump) and put in some marbles, say 6, in with the sand. This helps the sand from 'clumping' on you when you have to do a restart.

My next tank will have this system also.

[PHL]

Fluidise bed filters do not produce as much CO2 as CO2 injection systems; if they did, the bacteria would be dead! So there is no concerns there.

The concern is with power failure. Due to the design, it needs the constant water flow to aerate the media; no water flow, no aeration, you get dead bacteria (I think the figure quoted was after 30 minutes). When power comes back on, you will probably get dead fish as well due to toxins relased, and no ammonia/nitrite/nitrate conversion. Hence even with its cheap price, it's not very popular due the the inherent risk of the design.

[Gigitt]

Fluidise bed filters do not produce as much CO2 as CO2 injection systems; if they did, the bacteria would be dead! So there is no concerns there.

The concern is with power failure. Due to the design, it needs the constant water flow to aerate the media; no water flow, no aeration, you get dead bacteria (I think the figure quoted was after 30 minutes). When power comes back on, you will probably get dead fish as well due to toxins relased, and no ammonia/nitrite/nitrate conversion. Hence even with its cheap price, it's not very popular due the the inherent risk of the design.

Did you read the Link at all?

Actually the FBF is better in recovering from a power failure than a canister filter!

I was not comparing the performance of adding CO2 to a tank with a FBF vs CO2 bottle injection, but more that if you want that little extra CO2 for plants then this is a cheaper solution with added benifits of extra biological filtration! - and pretty much maintenance free.

[PHL]

Did you read the Link at all?

Actually the FBF is better in recovering from a power failure than a canister filter!

Yes I did, and the article was positive on FBF. OTOH, I've also read several negatives from people who have used them as well (admittedly in marine setups). FWIW, I think the bacteria, once established, are a lot tougher than we give them credit for; I've had a canister off for 12 hours without a problem.

Edit: BTW, I have no experience with trickle filters as mentioned in the article, so cannot comment on that; perhaps drying out could be an issue?

[CThompson]

1) The bacteria will only produce the equivalent CO2 levels as equals to the amount of bacteria. The level of bacteria will only reach the level that the fish waste can provide for their dietary needs. Due to the fact it is a plant tank, I expect you wont have many fish, which means you wont have an excess of CO2 from the bacteria as their waste products from the fish won’t support a sufficient level of bacteria to produce too much CO2.

2) A fluidised bed filter is NOT an alternative to a CO2 system, a FDF will only produce the equal amount of CO2 as the level of fish numbers control, by their waste. In a plant tank, you want to produce CO2 at the level required for the plants (dictated by the numbers and types of plants). And yes, at night the FDF will still produce a similar amount of CO2. Dependant on a whole bunch of interconnected water parameters, it is feasible that the CO2 produced by the FDF may at nighttime tip the balance and cause you problems. Plants will expel CO2 at night, and you will get incredible pH fluctuations from day to night. especially for the first 6-8 months. I had CO2 controller on my old plant tank which displayed a continual pH reading, and it was all over the place (AM/PM), but settled down after six or so months.

3) The bacteria levels will be dictated by the fish waste produced that will support them.

4) Answered above. I doubt you will be able to limit the amount of bacteria by regulating the amount of media.

5) Yes you can have too much media for bacteria require. They need food, oxygen, and a surface to live on, any one may be a limiting factor for the bacteria to exist.

6) No, but they can be very good in the right situation, which yours is not.

7) NA

8) They will NOT reduce your tank maintenance. How can they? They do not do anything to the nitrate levels, nor tackle solid waste (the later of which the plants in fully set up plant tank will use).

The use of a FBF is not conducive to a fully planted plant tank. If for no other reason than it will be too efficient at removing ammonia – which plants themselves use as a fertiliser (provided you maintain your pH below 7).

It will definitely NOT be a substitute for a CO2 system, either fully automated or a yeast system.

If I can help you further feel free to call me at home on 9541-4195.

Craig

BTW I didn’t read your included links (no time), but one of the advantages of a FBF is their recovery time after a power outage as compared to other bacterial medias/systems. This is due to the FBF supporting the growth of young bacteria (who produce the bulk of the babies), and knocking off the older generations of bacteria who don’t produce young.

Any biological media will be in trouble if the water flow goes off. One advantage bio balls have, is if the power does go off, they will not run out of oxygen (the usual shortage in power failures for biological medias). Provided that the bio balls stay moist (as they will in an enclosed system), they will have the best recovery time after a power stoppage.

In my opinion, in a fully set up plant tank, you don’t need any sort of biological media as bacteria will just be competing with the plants for the waste produced by the fish. Your most likely limiting factor on your plants, assuming you are fertilising, will be CO2. Go back to your yeast system, or make a big hole in your pocket and purchase an automated system. Sera make a system that have a regulator with a compatible fit for Soda Stream home made soft drinks, so once you have mortgaged yourself for all the gear, the CO2 will be cheap – a real factor to consider as you will constantly need to replace the CO2 bottle as it empties.

[Gigitt]

CThompson all you pointsa are valid, but I want refering to a Planted Tank and not a Plant Tank - my wording sorry.

My 4ft Tank is planted and has about 35 tropical fish... By adding the FBF to my tank, it could help break down the extra waste the plants are not using and clogging the filter - hence the reduced maitenance. The extra CO2 Generated by the FBF will help the Plants grow as well.

I run a 2 outlet air filter 24/7 so that any extra CO2 generated at night will hopefully be expelled from the tank via surface exchange.

[CThompson]

A FBF will not break down any more waste than any other type of biological system. It has the capabilities, but in your system, it will be overkill. Their advantage lies in the fact they have such a massive surface area (where bacteria can live), that they can deal with the waste from a huge number of fish (the downside to this is that the huge number of bacteria will strip the water of oxygen and return large amounts of CO2 to the tank). The other advantage a FBF has, is their ability to deal with fluctuating fish numbers. If a person adds or subtracts large numbers of fish from a system, the FBF will be able to pick up the slack and deal with the sudden increase of fish waste if large numbers of fish are put back into the tank.

If you have air going into the tank 24/7 as you mention, how can the FBF add CO2 to the advantage of the plants during the day. And at night the aeration will blow off the CO2 just as effectively as during the day.

As you say, you haven’t got a planted tank, but a tank with plants in it. This is a very different situation. If I were in your position, I wouldn’t go with a FBF as the main benefits to this choice of filtration will not be fully exploited with your tank. Use some sort of media in a filter such as Matrix or Ehime’s Effisubstate, and give the FBF a miss. I feel you are “hooked” on the novelty of it and are trying to justify using it on your tank. These aquarium gadgets are great!

If you use the FBF it won’t hurt, but choose it fully knowing the reason for your choice.

Craig

[Magica DiSpell]

Hi Gigitt,

Sorry I only just now saw your post. Tony - my better half - wrote the article you are referring to based on our own experience as well as his research on the net.

Fluidized bed filters are very efficient in removing ammonia from the water and the amount of bacteria colonizing the filter will be determined by the amount of food (ammonia, i.e. fish waste) available to them. So, don't cripple your filter by removing substrate. On the other hand there is no such thing as too much substrate in your filter, provided it is all fluidised (lifted by the water) and does not squirt out the top. If there is not enough food, then part of the available surface will not be colonised.

Powerfailures are a bit of a dicey point. They are a problem in that dead bacteria impose stress on your tank by removing oxygen from the system (Biological Oxygen Demand - BOD - increases when waste - even dead bacteria - are broken down). Even though fluidised bed filters recover faster from a powerfailure, they also cause more problems during the failure, because more (dead) bacteria means higher BOD and therefore less oxygen for the fish. Having said that, the filter column is quite separated from the tank by hoses and oxygen has to move into the filter column by diffusion, which would take longer in comparison to an undergravel filter, where the dead bacteria are in the substrate of the tank itself. We were very lucky, we never had to put that theory to the test . Our neighbours were always able to supply us with power when the storm disrupted our power.

Fluidised bed filters cannot be a substitute for a CO2 injection system and they certainly don't cause any problems even in tanks with only very little aeration (like surface agitation). Our tanks were not extremely oxygenated and we never experienced any problems. If you are after a planted tank keep using your Coke bottle CO2 injection system. In combination with aquatic plant food and light, it will cut down (but not eliminate) the need for waterchanges, because nitrates are removed by the plants.

By the way, Craig, plants are not able to use ammonia directly. In fact, plants can be used as an early warning system. I found that when my filter efficiency went down and ammonia levels increased in one of my tanks recently, the plants, not the fish were the first organisms in the tank to look bad. So fluidised bed filters do not hinder plant growth. They are just very efficient (quick) to remove ammonia from the water and convert it to nitrate, which the plants can use.

I don't understand why a fluidised bed filter, which costs considerably less than a canister filter or a "wet n' dry" filter to set up would be overkill. They have the potential to filter a lot more water than a 4ft tank, but that doesn't mean that they are not suitable.

Gigitt, I hope that this answers some of your questions and clarifies a few other things. If you have any other questions, please feel free to ask.

[Gigitt]

Thank you Craig and Magica.

You are both full of knowledge.

My main reasons for looking into FBF was to reduce my canister filter cleaning (I have 2 on my 4ft tank). I do it once a month, and if I can do it less then all the better.

Hey less time cleaning.... more time staring aimlessly at the fish swimming around!

The hardest part is that this tank is at my parents place so I do not get to appreciate it very much... only a couple of hours each weekend if that!

For the last 2 years I have not run the CO2 Coke bottle due to the fact that you really need to be there and swish it around every couple of days. I just cannot afford a $1000 autimated CO2 system. I have my own place now. I have a hard enough time making sure the fish are fed!. Mum or my sister sometime miss feeding them as they forget or are working/going out at night. The fish are still doing well. So I'm Lucky.

I would like to play with FBF - even build my own out of PVC and sand... but I will have to get the 4ft tank to my place. To do that I have to strengthening my wooden floor to take the weight of the tank.

Thanks again for all you comments.

[CThompson]

Sabine,

Please explain more on plants not being able to use ammonia as a fertiliser. Once it is broken down to nitrate, yes they can use it as you say (I had to add nitrate to my planted tank), but I also thought they had a hand to play in the use of ammonia itself (provided the pH was below 7). Do the plants use ammonia itself as a fertiliser (which you will say “no” to), or do they play a hand in breaking it down to nitrite and then nitrate (which they use)? Or do they not touch ammonia at all?

I’m positive that I have read that below a pH of 7 the plants can use ammonia, once the pH goes beyond 7, ammonia becomes ammonium (or visa-versa I forget), which the plants don’t use. Which is why a planted tank needs to be kept below a pH of 7, and indeed, why plants require a pH of below 7.

Or is that all tied up with the plants inability to access CO2 at a higher pH of 7?

I personally don’t think a FBF is required on Gigett's tank simply because on a single standard tank, with a stable fish load, the “pros” of the pros and cons of a FBF will not be needed. In your old system Sabine, your fish levels would fluctuate quite dramatically as you sold fish. In your case, a definite argument could be found to support the benefits of a FBF being utilised.

It won’t hurt Gigitt’s tank, but neither will it hold any benefits over say a handful of Matrix or Efisubstate (how ever that is spelt). Which will be a lot cheaper than a FBF, and at the end of the day, do what the FBF is being asked of it in her system.

Also, Gigitt seems (initially) to be thinking she can use the FBF as a substitute for a CO2 injection, which by now I’m sure she will have changed her mind about. However, if this is her main consideration in utilising a FBF, her desire for it is founded on in incorrect premise.

Gigitt,

A FBF is a biological filter (as you’d know). When one cleans a filter, you are cleaning the mechanical side of it. Of course, any biological media included with the mechanical media will also become dirty and require rinsing. However, the mechanical side of the filter will get just as dirty, and just as fast, regardless of wether you use a biological media included with your current filter, or a FBF in line with your current filter. Don’t forget, the water to a FBF needs to be cleaned mechanically before it gets to the FBF.

If you want to reduce your workload on the tanks at your parent’s place, here are two things that will do that. A larger or additional filter (of whatever sort). Or less fish. Less fish = less sh*t = less to be captured in the filter = less maintenance.

Craig

[Gigitt]

Thanks Craig

Oh BTW: I'm a he and not a she ... ROFLMAO

[CThompson]

I did wonder that when I wrote "she"

[catalyst]

The best think with a FBF is it uses an external pump so if you use a 12v pump you can run it off a battery in a black out, I havent found a 12v canister yet.

[CThompson]

Catalyst,

The advantage of using a 12v pump to keep the water flow going during a power outage is a very interesting spin on the issue.

How do you have this set up? If the water going through the FBF needs to be prefiltered, it needs to go through some sort of mechanical filter. Following from that one would assume the FBF is “in line” with this mechanical filter. How do you get a 12v pump into that system?

Craig

[Gigitt]

When we had a blackout I just used my PC's UPS (MGE Elipse 1200).

It ran my Aqua Via 650 for 6 hours.

Or you can buy an Eheim inline pump. There is a 12V model used by PC overclockers to power their watercooling setup inside their Computers. You can gerry rig this to a car battery to keep you going. But yeah you do need to prefilter it (ie Sponge) and it will probably have to be tied in with some piping with taps to divert the inlet from canister to 12V pump.

too much work...

UPS is simpler and can be more permanant.

EDIT: UPS is an Uninteruptable Power Supply.

[catalyst]

I am using one of these purchased from a PC shop, I use a sponge on the end of a hose for the intake and the pump runs on a 12V plug pack, if the power goes down I just plug it in to my car battery that is always on triccle charge.

[Gigitt]

I am using one of these purchased from a PC shop, I use a sponge on the end of a hose for the intake and the pump runs on a 12V plug pack, if the power goes down I just plug it in to my car battery that is always on triccle charge.

Yep that is the pump I was talking about.