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Air pump for fluidised bed sump

goldscapes

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21 Aug 2018
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Hi there,
I'm in the process of setting up a second hand Evolution Aqua ReefPro 900s aquarium for freshwater use, it comes with a sump.
I have filled 25% of the main chamber (3.5L) with K+ media and tried using a JBL a300 (300lph) air pump to fluidise the media.
The pump size was based on a YouTube video recommending 1 litre per minute per litre of media, in this case 1x3.5x60 = 210lph.
Unfortunately, this was barely enough to move the media, let alone fluidise it.
So I bought a Eheim Air1000 pond air pump (1000lph), which unfortunately was faulty and only one of the two outlets worked, so it's being returned.
I did try it out with the one working outlet and it was significantly better but I'm still not convinced it would get the media moving properly even with both outlets functioning.
Does anyone have any suggestions?
I'm using a pair of 30cm air diffusers like these could they be the problem?
Has anyone succeeded with a similar setup? What air pump are you using?
I'm pretty close to cutting my losses and reverting to traditional filter media, not least due to the noise of the larger air pumps (the tank is in a living room after all).
Any thoughts gratefully received.
 

goldscapes

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Use a water pump instead, will be so much better and more importantly, quiet.
I like the suggestion, especially the "quiet" bit :)
My research up until now suggested that air pumps are necessary to produce an oxygen rich environment for the bacteria.
Makes me think though, would the fluidised media get sufficient oxygen from the air as it tumbles?
 

john6

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I like the suggestion, especially the "quiet" bit :)
My research up until now suggested that air pumps are necessary to produce an oxygen rich environment for the bacteria.
Makes me think though, would the fluidised media get sufficient oxygen from the air as it tumbles?
you need surface movement for gas exchange, doesnt matter how its done, plus you will get surface movement in your dt as well.
Air pumps dont add oxygen themselves, they just cause surface movement by the bubbles reaching the surface.
 

goldscapes

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I must have misunderstood, I assumed that it's the air bubbles coming into contact with the media that make the difference in a fluidised bed, if it's just the oxygen content of the water then, "happy days," I can use a powerhead instead, maybe something like this with a venturi.
 

john6

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I must have misunderstood, I assumed that it's the air bubbles coming into contact with the media that make the difference in a fluidised bed, if it's just the oxygen content of the water then, "happy days," I can use a powerhead instead, maybe something like this with a venturi.
Cheap and noisy. This is just my opinion but look to brands like eheim, sicce, aquarium systems, jebao/jecod, hydor. the all pond solutions stuff is really naff imo. Just to avoid confusion, when i say water pump I mean more a powerhead which circulates the water.
 

john6

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Jobiwan

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I just ordered a freshwater sump setup from Aquariums 4 Life, both the tank and sump will have glass covers, my K1 chamber will be air driven to ensure plenty of O2 is available, a relatively sealed system would tend to be O2 deficient with a power head driven setup in my opinion, if you are operating without covers a power head would be the way to go
 

goldscapes

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I just ordered a freshwater sump setup from Aquariums 4 Life, both the tank and sump will have glass covers, my K1 chamber will be air driven to ensure plenty of O2 is available, a relatively sealed system would tend to be O2 deficient with a power head driven setup in my opinion, if you are operating without covers a power head would be the way to go
No CO2 so no covers, thanks for your input 👍
 

goldscapes

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I just ordered a freshwater sump setup from Aquariums 4 Life, both the tank and sump will have glass covers, my K1 chamber will be air driven to ensure plenty of O2 is available, a relatively sealed system would tend to be O2 deficient with a power head driven setup in my opinion, if you are operating without covers a power head would be the way to go
Out of interest, which air pump will you be using?
 

dw1305

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Hi all,
Air pumps dont add oxygen themselves, they just cause surface movement by the bubbles reaching the surface.
They do actually <"add some oxygen">, it depends on <"bubble size and residence time">. Have a look at <"Aeration and Dissolved oxygen..."> for some more discussion.
I must have misunderstood, I assumed that it's the air bubbles coming into contact with the media that make the difference in a fluidised bed,
No, you are right, it does make a difference, the bubbles are retained in the media mass, and this has the effect of increasing their residence time.
I can use a powerhead instead, maybe something like this with a venturi.
<"Powerhead and venturi"> should be fine.
both the tank and sump will have glass covers, my K1 chamber will be air driven to ensure plenty of O2 is available, a relatively sealed system would tend to be O2 deficient with a power head driven setup
That is a valid concern where you have sealed system with either / or a <"large Biochemical Oxygen Demand"> (BOD) or a <"system without plants">. I like the <"EDPM"> diffusers, they produce fine bubbles, even at lower working pressures.

cheers Darrel
 

goldscapes

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Cheers Darrel.
Removing the check valves helped boost the output considerably and gives me more confidence that the media will fluidise once it has matured.
However, the noise of the air pump is still significant for a living room setup so I’ve ordered a Venturi powerhead to compare the difference.
 

goldscapes

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Ok, so the Venturi powerhead is in place and it’s so much quieter there’s no competition. I went for an eheim 650 powerhead in the end and glad I paid a bit extra, the ball system makes it really easy to direct the flow where it’s needed. About half the media is now fluidising and it’s not matured yet so hopefully once it has everything will get moving nicely.
 

goldscapes

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It’s also worth noting that evaporation, which was also a real problem with air stones, has dropped to manageable levels.
 
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