Lava rocks as a biological filtration

[zanguli-ya-zamba]

Hi,
a friend of mine have a 900 L tank and he is using lava rock from a congolese volcano in his filtration.
I was wondering if he can use this type of rocks for that purpose ?
or it's not enough porous for that.
the rocks he use are 4 to 6 cm diameter.
and by the way he is also using the same lava for substrate but in much more smaller size, with a layer of laterite under that.

thank you

cheers
Zanguli

 

[roadmaster]

Is fine for biological media,but not very good for substrate in my view.
Is too sharp for fishes that frequent the bottom, and perhap's for root's of plant's should they be rooted.(my opinion)
Have seen bellies of bottom dwelling fish like,pleco's,cory's,loaches,get sraped up on sharp substrates and this could increase chance of bacterial infection.
Smoother substrate would be my choice .

 

[zanguli-ya-zamba]

hi master road,
I totally agree with you, but it's a fish less tank and he doesn't want to put fish so that's good !!
for the roots I might check but I think you're right, but can it be possible for the roots to be damage just by growing in there ? or it can be damage only when you uproot and plant ??

thanks for your answer
regards

 

[roadmaster]

I think both maybe. But then again,,I am often amazed at the weed's that grow from crack's in my sidewalk's on weekly basis during summer.