Lava rock any good?

29 Mar 2016
Reaction score
Hi guys is lava rock any good for a marine tank? Or would you recommend a different type?

Also with my tank I will be starting the cycle process soon, is there any negative effect of having live rock during this cycle?
The cycle is not about the water, it is all about the rocks. More specific, the dead things in and on the rocks. And how they are disposed of, eaten or rot away. And the good bacteria population growing within the rock, digesting the dead critters.

Yes, there are some free floating bacteria in the water. But is nothing compared to the numbers inside porous rocks.

Lava rock can work. But note that new ones can leach more phosphates into the system than wanted. Also they are not as porous as good quality liverock.
Yip you need live rock. Not sure what you mean by lava rock. lava rock I know, I used to use in my tropical tanks but that wont work in marine i think. (They have very sharp edges etc and I think they not porous enough for bacteria)
Last edited:
Thanks guys, guy at a fish store was saying it's better than most rock for marine tank.

Will be getting live rock then.
I've seen success with either, lava rock can be used as base Live rock. Hell I've even seen success with clay bricks...
I got 3 rather big pieces of lava rock in my holding tank. Big and round. Not the easiest to build with either.

They do hold a lot of water.

But size on size, they are heavier than liverock. Depending on where you buy, I'm sure you will be better off buying real liverock for the same volume.
Thanks guys, might use some to add some contrasting colours

It will all be covered by algae and or corals later on anyway, so don't let initial colours dictate your rock choice.

You want as much surface area as possible for bacterial colonisation, so rather use that space for proper live rock.
I would not trust lava rock in a reef, a lot of them has metal streaks etc inside that I have seen, so I would be too scared that it would leak heavy metals and other nasties into the water.
Top Bottom