Freshwater DSB.

[Simonauv]

For those that don't know a DSB is a deep sand bed and is commonly used in marine tanks to help remove nitrates naturally.

Basically it works by having an aerobic layer and on top of the sand (the top 1cm ish of sand) in which aerobic organisms converted organic matter into nitrates which is then passed down into an anaerobic layer (the bottom 4-5 inches) of sand in which anaerobic bacteria lived that converted the nitrate into atmospheric nitrogen that forms bubbles that push their way back up through the substrate and up through the water back into the air.

There is more to it than that (like seeding it with infaunal organisms from natural environments) but that's it in a nutshell. It requires a deep bed of very fine sand up to 5 inches deep (prob not very good with a lot of digging cichlids but may be good in a sump). I currently have a dsb on my 6x2x2 marine at work as the primary filter that doesn't look pretty but works very well.

Just wondering if anyone has had a crack at it with freshwater tanks?

[Eddie Salita]

A fellow up here who used this theory in a tang tank. Always had Zero nitrates, and only did water changes once a month. He doesnt keep fish anymore unfortunately. I have never been game to try it on my tangs. I also tend to agree with the fact it doesnt look pretty. BUt has the benefit of never doing a gravel vac . He kept some xenotilapia in there too. They only ever sifted the top inch so that was ok. He also had excellent water movement, but little aeration.

I would say it s very possible... Are you going to give it a go?

cheers,

Jason

[Ash]

a buddy has sand in really huge sumps under his 8x2x2s to try a freshwater DSB - I don't think it's working because his sand is too coarse

[Simonauv]

For a DSB to work you also need to have continual recruitment of the aerobic organisms because otherwise their efficiency seems to plateau and then decline. By using sand sifting organisms like sea cucumbers I was able to turn over the aerobic layer creating an effect like felling a tree in a rainforest - a race to fill the hole lol This way the aerobic layer stayed vital. Maybe the sand sifter cichlids perform a similar job. On my 3x2x2 marine I had back in Australia I had a 5 inch 'lip' that covered the bottom part of the tank so you couldn't see the DSB from the outside. Not going to try it here, but may do when I return home. I used sand from Nelson Bay (Anna Bay White) for my marine DSB that worked really well. Pool sand/dust should work ok. Has to have a diametre < 0.1mm

I also think people worry about introducing something predatory or pathogenic when collecting sand/gravel from natural freshwater systems. Maybe need a quarantine tank for the sand first .

[Eddie Salita]

Maybe those burrowing cone snails which are prety much ever present (for me anyway ) help do that at the deeper levels of sand too? The sand in question was very fine straddie white sand.

[Simonauv]

Maybe those burrowing cone snails which are prety much ever present (for me anyway ) help do that at the deeper levels of sand too? 

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Are they detritivores or herbivores?

[Eddie Salita]

Are they detritivores or herbivores?

Good question. Just had a quick search on them. Known as Malaysian trumpet snails, or Melanoides tuberculata. They certainly dont devour my plants. Info I have found indicates they are an algae eater and food scavenger. I have seen them munching on dead leaves, but not live ones in my tanks. One site I found says detritus rich mud and sand is prime habitat, and they are very tolerant of low oxygen levels. Which would support the theory that they either consume it, or just like to live in it. Havent found anything definitive so far...

[Simonauv]

hmm - well logic assumes that organisms that are in the detritus will be eaten by an organism that eats the detritus so would perform a similar function to the sea cucumber??? Maybe.... lol