Confused (Fluidized Media)

Thomas Mack

Feeder Fish
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Feb 23, 2020
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Hello
I will be getting a 125g Sump built with a chamber about 75g space for fluidized media ( HEL-X 13 ). I have read many threads on pros/cons on the best way to move the media, and that’s where I’m confused. I am asking for advice from the PRO’s here so I can get it right.
Thank you
 
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fishdance

Polypterus
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Jan 30, 2007
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The media you mention is usually used as a moving bed filter similar to K1 media.

It isn't a fluidused bed situation, rather a bio film filter even though it moves. They both do biological filtration but in very different ways. So what you try to achieve will vary depending.
 

Thomas Mack

Feeder Fish
Original poster
MFK Member
Feb 23, 2020
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The media you mention is usually used as a moving bed filter similar to K1 media.

It isn't a fluidused bed situation, rather a bio film filter even though it moves. They both do biological filtration but in very different ways. So what you try to achieve will vary depending.
Now I’m lost on the Bio-Film part...sorry. I understand how they bump into each other and knock off the dead BB and the healthy BB grows...etc. I’ve read that either air diffuser or wave makers are ideal for them. I also read that air diffusers aren’t needed as it doesn’t need oxygen bubbles to move it. I need help understanding what is best to help make the environment healthy for my fish.
 
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BIG-G

Goliath Tigerfish
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Dec 12, 2005
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Now I’m lost on the Bio-Film part...sorry. I understand how they bump into each other and knock off the dead BB and the healthy BB grows...etc. I’ve read that either air diffuser or wave makers are ideal for them. I also read that air diffusers aren’t needed as it doesn’t need oxygen bubbles to move it. I need help understanding what is best to help make the environment healthy for my fish.
Your understanding is correct in that the media bumping into itself is supposed to help knock off bits of weaker bacteria (bio film) and make room for more robust and productive bacterial growth.
K media or similar are usually plastic and neutrally buoyant.
The fluidized bed media (usually sand but can be other things) works under the premise of surface area for the bacteria to attach but different in that it doesn’t allow for the bacteria being knocked off although I’m sure that this happens in a fluidized bed filter somewhat.
Also the fluidized bed uses the water flow to lift and stir the media. With k media you can use air or water flow or both to lift and stir the media.
 
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fishdance

Polypterus
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Jan 30, 2007
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Bio film filtration is about encouraging advanced bacterial cultures well beyond the basic nitrosomas and nitrobacter nitrification process. Many of the cultures are too complex for our understanding as they diversify, develop and form symbiotic dependencies. Some bacteria sub cultures create exo barriers preventing antibiotics from working on the rest of the colony for example. Others produce food for other bacteria that have become too specialised. For bio film filters, surface area and time to develop are required so you would use a gentle roll of media for aeration and nutrient supply. This is called a moving bed. Although some bacteria dislodgement occurs on the outside of media, the majority is retained as this is the objective.

A fluidised bed filter is about removing much of the old bacteria to encourage young active re-growth. These are best for nitrification and a more vigorous turnover of media is required. K1 / Helix is not the best choice for this but is commonly used because it's mis-understood.
 
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duanes

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I made my fluidized bed in a cylinder, but it doesn't matter what shape it is, as long as it doesn't have dead spots, and works.
I used a water pump (as opposed to an air pump),to move media, and for the type media, used aragonite sand.
By using the sand beside being media for beneficial bacterial film to live on, the aragonite buffered alkalinity, and helped maintain a stable pH.
Any acids in the water were buffered by the calcium in the aragonite which would dissolve it over time, so every couple weeks I'd add another Tbsp or so. As you can see I didn't pressurize it, to make maintainence easier.
I found when pressurized, during power outages, media could get back siphoned into the tube, and the unit had to be taken apart to remove clogged media, unpressured, and by using a check valve, less back siphon, and easy to remove if it did back siphon, I could simply pull out the tube and knock media out.

water flow was just enough to keep media moving (fluidized) but not enough to push it above the rim.
 

Matteus

Redtail Catfish
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Jan 6, 2018
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Bio film filtration is about encouraging advanced bacterial cultures well beyond the basic nitrosomas and nitrobacter nitrification process. Many of the cultures are too complex for our understanding as they diversify, develop and form symbiotic dependencies. Some bacteria sub cultures create exo barriers preventing antibiotics from working on the rest of the colony for example. Others produce food for other bacteria that have become too specialised. For bio film filters, surface area and time to develop are required so you would use a gentle roll of media for aeration and nutrient supply. This is called a moving bed. Although some bacteria dislodgement occurs on the outside of media, the majority is retained as this is the objective.

A fluidised bed filter is about removing much of the old bacteria to encourage young active re-growth. These are best for nitrification and a more vigorous turnover of media is required. K1 / Helix is not the best choice for this but is commonly used because it's mis-understood.
Wow. This is very informative thank you.

what is the best use for k1-helix media then if this is the common misunderstanding?
 

aotechs

Jack Dempsey
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Nov 17, 2015
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About 120 Litters
If you want to use air, 60 LPM would get you started. If you want to add more media over time or throw in some air stones to the display, an 80 to 100 LPM air pump would be a good option.

Air pumps and tumbling media can be noisy if your display is in a living room. Try some simple tests using your TV or similar device and a free decibel meter app. Adjust your TV etc. volume level to match advertised decibels for the pump.
 
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