# De-nitrification from lava rock?



## Aislinn (Jul 31, 2009)

I was playing on the internet this morning and read an article that said:

'you may get some side benefits from using it (lava rock): after it has been in place for six months or so, you may witness some slow decline in nitrate in the aquarium. This is due to de-nitrification carried on by certain bacteria, deep in recesses of lava rock, where the water is anoxic. If you pull out the rock and drain it, or worse, if you dry it, the de-nitrifying effect will be cancelled. So, treat matured lava rock as respectfully as you would a matured sponge filter.'

Has anyone ever noticed this?

Thanks,
Aislinn


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## DJRansome (Oct 29, 2005)

Lava rock would act like the material in your filter, as would gravel and other objects with lots of surface area. But beneficial bacteria produce nitrate, they don't "eat" it so I don't know how this could happen.

I don't like lava rock, it's too rough when the fish bump (slam, LOL) into it.


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## TKC747 (Dec 5, 2008)

Although not everybody on this forum agree with this, Seachem's Matrix supposedly house anaerobic bacteria in the core of the matrix pebbles. Supposedly, if the water flow is fast enough, beneficial aerobic bacteria colonize on the surface. As the water passes through the pores of matrix, the oxygen rich water is de-oxygenated by the aerobic bacteria, and nitrates are converted to nitrogen in the core of the matrix pebbles by anaerobic bacteria. Salt water tanks have this process going on. I don't know if Seachem matrix actually works in fresh water but that is the approximate "theory" behind lava rock housing denitrifying anaerobic bacteria which converts nitrates into nitrogen.

Hope that helps a little

Tom


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## Aislinn (Jul 31, 2009)

Further research has that some people have used smaller pieces of lava rock in their filters in place of floss, saying it doesn't have to be continually replaced, only washed out. Has anyone tried this? I not sure it would catch the smaller pieces of material though.


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## kmuda (Nov 27, 2009)

I dislike use of Lava Rock myself but I keep South Americans. At least with South Americans, use of Lava Rock is strongly discouraged as the fish will tear themselves to shreds on it. I don't keep Africans and do not know if the rules change.

But yes, the concept is sound. You can achieve some measure of denitrification with Lava Rock. Just don't expect to eliminate nitrates or even expect the measure of denitrification being achieved to be significantly noticeable.

As for Matrix, yes I believe you can achieve results using Matrix. Please see the below thread for a previous post on the subject.

http://www.cichlid-forum.com/phpBB/view ... 3&start=15

I use Eheim EhfiLav in numerous locations. In general, it is in the first tray of my canisters. It makes a wonderful mechanical screen and still retains its biological properties even when used in this fashion. It's also about as inexpensive as prepackaged media can get. It also works well in the optional media cartridges for Penguin and Emperor filters.


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## DJRansome (Oct 29, 2005)

I use a similar Eheim media. If it is eating any nitrates, I was not aware of it. I also have the full spectrum of sponges, crushed coral, fine filter pads, etc.

If you want to get rid of nitrates without water changes, plants work best IME. However, you still need water changes because nitrates are not the only pollutant. It's just that nitrates are easy to measure to gauge the level of waste generated.

And plants bring their own level of work and maintenance requirements. Finally, zero nitrates is not desirable with plants, even if they cause it. With zero nitrates, other types of algae grow (hair, spot) and the plants will die and you will get cyanobacteria.

It's all a balance. No plants and the "usual" filter set up with 50% weekly water changes is the easiest, IMO and IME.


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