Lava rocks for nitrate removal

[Knew tooth is]

Does anyone have good, bad or other experiences with addition of lava rocks to facilitate removal of nitrate- the rocks serving as havens for reproduction of detoxifying bacteria.

 

[Alison]

I don't have any personal experience no. I have heard of some more serious scapers that will use lava rock as a base level or on filter bags to build height more cheaply than using just massive amounts of more expensive substrates. All of them say that all the nooks and crannies of the lava rock do provide loads more surface for the bacteria to adhere to. I haven't see any actual studies nor do I have any personal or antidotal evidence to offer.

[AdamTill]

It’s actually more likely that the large pores will collect debris and create nitrate.

The whole full cycle concept is not impossible, but difficult to setup in an average aquarium

[Daniel]

I can see why all the surface area on lava rock would help with providing surface area for the beneficial bacteria. But I have also read that not all surface area is equal.

The authors of this paper claim that the density of the Nitraspina, Nitrospinacacae, and Nitrospria bacteria (the famous beneficial bacteria) was much greater on the surface of plant leaves than either gravel or plastic (I didn't know that, I thought all surface area was the same, apparently plants enter into a beneficial relationship with bacteria and help provide the oxygen and organic carbon the bacteria needs).

[rdaled]

Lava rock is the only filter media I have on my 20 gal and have never had an ammonia or nitrite issue. It provides plenty of surface area for beneficial bacteria. However, it will not remove nitrates. I don’t think any filter media will do that. 

[Mr. Ed's Aquatics]

31 minutes ago, AdamTill said:

It’s actually more likely that the large pores will collect debris and create nitrate.

The whole full cycle concept is not impossible, but difficult to setup in an average aquarium

I disagree that it would create nitrate. I have 2 75 gallon mbuna tanks,  one with artificial decor and one with a ton of lava rocks built into caves. The one with the lava rocks is always way lower in nitrates than the other on waterchange days and needs less water changed. Even though it has a little more bio load. I have a similar situation with 2 29 gallon planted tanks. The one with crushed lava rocks in the bottom does noticeably better than the other with regular gravel.

I think it would only be a problem in a tank with bad flow, which is it's own issue.