DSB filter

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qwe123

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Jul 30, 2008
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A pleco/guppy breeder gave a talk at my local club recently, and one of the filtration methods he employs is basically a deep sand bed inside a pitcher.


So he takes a pitcher (in his case an empty Brita pitcher)
puts a hollow tube in it with an airline
fills the rest with substrate
puts this in his sumps (I think, or maybe in his tanks)
and turns on the air, which creates water movement down through the deep layer of substrate (he makes sure it's at least 6 inches to create the anaerobic effect) and up through the tube.


Anyone see any problems with this method of filtration? There is no need for creatures to sift the top layers of the bed as the water is flowing through it due to the airline. But would it cause problems with the anaerobic bacteria at the bottom because there is so much water moving through it (instead of the gentle, slow movement a DSB usually has)?
 

OrionGirl

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If there's air being pushed into the substrate, it doesn't create an anaerobic environment. Air pumped through the water will keep in oxygenated.

Plants are and easier way to deal with nitrates in FW, TBH.
 

qwe123

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Air wouldn't be pushed into the substrate, it would be pumped into the tube only drawing water through the substrate (think undergravel filter concept)
 

jpappy789

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I'm also a bit skeptical about the pumping of air...if water is flowing through the substrate, regardless if the actual O2 bubbles are entering it, then you still have the potential of introducing dissolved oxygen. Not a lot, but some. The UGF concept require O2 introduction for the purpose of nitrification anyways.

Denitrification (generally the reason for using a DSB) is usually not favorable in aerobic environments. I say usually because there are exceptions. It'd be hard to say if the environment this person is creating is aerobic vs anaerobic without actual numbers though, so I suppose given the right conditions (oxygen consumption somehow outweighing production) you could get anaerobic pockets...but that could happen in just about any microenvironment within substrate, which begs the question: just how efficient is this contraption?

I prefer water changes and plants I were to have to give choices for NO3 removal "tools." There's also a pretty good write up on DSB's here:
http://www.aquariacentral.com/forums/showthread.php?215174-How-Freshwater-Deep-Sand-Beds-Work
 
Last edited:

OrionGirl

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The substrate used would be a factor, as well. From what I recall (and this was 10 years ago), it was determined that 4 inches is the minimum with a fine grained substrate, but with anything larger, you needed more...and things like crushed coral are large enough that 18 inches is needed to get any benefit.

I'd be hard pressed to come up with a benefit that would outweigh the risk involved when there are so many easier, safer alternatives. JMO.
 

qwe123

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Jul 30, 2008
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Just curious what risks would be involved? I'd imagine if it doesn't work as a DSB filter, it would still work as a regular biological filter...
 

jpappy789

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Feb 18, 2007
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Most times when people worry about purposefully creating anaerobic environments you it gets brought up that H2S formation can occur...which is possible, but not always likely.

In this case, IF the contraption is more aerobic than not...well, then it doesn't really hurt anything since it's just water flowing through substrate...I suppose it could be medium for nitrification if there's enough O2. Like I said, it's hard to say 100% either way without isolating the system and getting some hard numbers to compare.
 
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