Anyone know this rocks?

Hi

Im starting my 800L malawi tank tonight.

Was hoping to get a 3D Rocky look as background. Cant really find these panels anymore it seems and they were expensive apparently.

What I did find are these rocks that was called "Bio Rocks" by the chappie at the Pet Store.
I was assured that it would be ok in my tank. Paid about R20.00 a kilo. (Actually less)

Now im beginning to wonder about these rocks. Wouldnt mind if they raise the PH a little.
Although im putting Silica as a substrate. Would this be too much maybe?

I posted some pics of them. Anyone know them?

Thanks

 

its basically like a defective brick\clay product.

Some people use it as bio material in their sump filters also known as lava rock commonly

 

The dark coloured rock looks like lava rock. Does the rocks have like sharp edges.

 

Yeah it does have sharp edges.
Would it maybe be dangerous for fish?

 

If a fish bashes into that rock or scratches against it, the fish could be harmed. Also very dangerous for fish eyes.

 

Was hoping to use some big ones of these type because of their leight weight.

Then again, my tank was just delivered - it is a sturdy one - 25ml steel square tubing. 10ml double glas bottom.

Maybe I can go for something heavier -

 

Anyone maybe using these rocks at the moment?
Anyone had some fish injured by it?

Cant decide which rocks to use in this tank!

 

The problem with injured fish is they often lead to disease in the fish\tank

 

Maybe post some pics of your tank, that way the members can give some better ideas ?

 

Even tho the lava rocks have sharp edges i have used them in tropical and malawi tanks before. I have had no problems with the rocks, only jus the few scratches on my hand when packing the rocks in the tank. The fish were perfectly safe. Just be careful when trying to catch your fish out of ur tank cause then you can injure them when they go close to the rocks.

 

Yeah thanks for replies guys.

Decided to get some other ones. Bone Rocks