# DIY fluidized bed filter ! 300gph, 3 lbs pool sand <24 hours



## mbuna nate (May 2, 2017)

Hey guys, I was looking for a good diy to treat myself after taking the cpa exam and not having to study the time. I build a fluidized bed filter, which I had never heard of until the day I built it. Basically you use a power head to pump water into a bottle full of sand to turn the sand to liquid. This way all 3lbs of sand are in direct contact with water at all times. Even better the sand colliding knocks off old bacteria and only allows the youngest most efficient to survive. Most accounts I have heard are 6,000 times its own surface area, so one cubic foot provides 6,000 cubic feet of growing space. Seeing all trillion particles of sand blasting around I am inclined to believe it. I will post pics tonight and ask questions about how I made it if your interested. After I had the materials it took me about 20 mins to complete with a power drill and saws all. Lots of videos online too and super easy, you just have to know they exist. Pics to come


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## Mcdaphnia (Dec 16, 2003)

I have used these in fresh and salt. They work. Trumpet snails seem to be the only freshwater problem that can interfere with the function of the pump and infest the sand no matter how much it moves. Saltwater has a lot more critters that can grow inside the filter. A few pebbles in the sand of the right size for your pump may keep some of these under control. I find the FBF and its plumbing worked better in the dark since otherwise algae can grow in it.


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## mbuna nate (May 2, 2017)

Im amazed at how useful it is, but it seems like they feel out of popularity a few years ago after people had problems getting the right amount of fluidization without sand blasting your tank, but it really isnt too difficult, too much sand coming out and your flow is too high or vessel is too small and vice versa if you see dead spots. I wanted to post my ghetto contraption to emphasis its ease but i think i will spend the rest of today perfecting it and post some pics with tips tonight. McDaphnia, did you make your FBF or purchase one? they are so unpopular it seems like there are some reasonable deals now


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## Mcdaphnia (Dec 16, 2003)

When they first came out I obtained every brand I could find, made a DIY, and wrote an article comparing them. One thing that may make them less than popular is that as the sand bounces, the grains become progressively smaller until they begin flying into the tank unless you preemptively adjust the flow rate down. I even had one, I think it was called Sandman that was quickly removed from the store shelves. It had more than its share of maintenance flaws. We hosted a Japanese exchange student that year and when she saw our fish room with a hundred tanks, she wanted a tank in her room for one koi. She picked a koi out at William Tricker's (Independence Ohio). I gave her the Sandman and a tank. I had figured they were a little tricky to operate, more than other makes, but this girl was a natural fish keeper. Her aquarium was always clean, pristine, perfection. One problem with the Sandman was noise, but hers always ran dead silent.

Look for easy access to remove old sand, clean the interior, and replace the sand charge. It only lasts so long. Match the filter model to the right size pump and have a way to adjust the flow without harming the pump. I like having a valve and a bypass, but that's only one way.


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## Caity (May 26, 2017)

I'm a little bit confused. Is this sorta like an under gravel filter but for sand?


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## Mcdaphnia (Dec 16, 2003)

Caity said:


> I'm a little bit confused. Is this sorta like an under gravel filter but for sand?


This is closer to a canister filter on backflush in aquarium terms. it also compares to a sand filter for a swimming pool and the sand is a very fine filter media. A swimming pool sand filter is mechanical and chemical filtration, not biological filtration like in most aquarium filters. The sand captures particles so that the water looks clear. Chlorine or sometimes ozone is separately used to keep bacteria out of the swimming pool. Running the sand filter constantly in an aquarium could cause it to begin to function as a bio filter. Running a swimming pool sand filter backwards makes it work closer to a fluidized bed filter. And Caity, you are probably now a lot more confused. A video might make it easier to understand.


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## Hock (Mar 23, 2012)

Today it is much easier to use K1 media instead of sand.


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