Lava rock

[Shaun Sweeney]

Has anyone tried using real lava rock as part of their filtration system?

 

[Joey waid]

I've seen it been used on the web.

 

[Shaun Sweeney]

I've seen it been used on the web.

My new setup will have socks (or sock material) as the 1st stage of the filtration. As it is a dedicated tank, I could easily have a couple of inches of lava rock as the next level - upstream of the skimmer.

 

[Joey waid]

I have thought about it too. I ended up getting live rock and busting up with a hammer. I just did not trust the lava rock being clean enough.

 

[Shaun Sweeney]

I've been poking around on the internet and it looks like it should be perfectly safe. I'll give it a try.

 

[clownfish chris]

It is safe. I have used it in place of bio balls when I first got in the hobby. I got rid of it for the same people get rid of bio balls. It was a nitrate sink. I would use it as base rock again if I needed to.

 

[cromag27]

I would never use any rock harvested from land.

 

[Shaun Sweeney]

I would never use any rock harvested from land.

Thanks for that. My thought was to use it right after my filter socks and before the skimmer. It would get a lot of water forced thru it.

 

[Shaun Sweeney]

It is safe. I have used it in place of bio balls when I first got in the hobby. I got rid of it for the same people get rid of bio balls. It was a nitrate sink. I would use it as base rock again if I needed to.

The nitrate sink idea still confuses me. Why wouldn't the lava rock - in a high flow area - act as a fluidized filter? If it did, wouldn't that result in a build up of good bacteria that reduced nitrates?

 

[AlexG]

The nitrate sink idea still confuses me. Why wouldn't the lava rock - in a high flow area - act as a fluidized filter? If it did, wouldn't that result in a build up of good bacteria that reduced nitrates?

The bacteria that consume nitrates are anaerobic meaning that they live in environments without oxygen. Lava rock in a high flow area will create an environment that is good for nitrafiying bacteria that utilize oxygen and produce nitrates as a byproduct. As there is an imbalance between aerobic an anaerobic bacteria a nitrate sink will be created. In a way the first part of biological filtration becomes too efficient and nitrates build up rapidly because there is not an environment that can sustain enough anaerobic bacteria to consume the nitrates being produced by aerobic bacteria. I battled high nitrates for years before I understood that the biological filters that I had in place for my aquariums were actually causing more harm than good. I eventually made a filter to specifically handle nitrates which ultimately eliminated the issue of high nitrates. Filter socks can also become a nitrate sink if they are not cleaned often.

 

[Shaun Sweeney]

Excellent! Thank you for that concise response. I won't be using lava rock in that area.