Making your own live rock with oyster shells

[inktomi]

Has anyone made their own live rock with oyster shells and cement? I think this could be a really cool way to make our own live rock in exactly the shape and size we like. The ratio is 1:3.1 by weight cement to oyster shell. Then use 50% by weight water for the amount of cement you use. I found this in a paper that was published recently - Relieving pressure from coral reefs: Artificial oyster rocks can replace reef rocks used for biological filtration in marine aquariums.

As an example, if you have a 10 pound bag of crushed oyster shell:

3.22 lbs of Portland cement CEM II with limestone
10 lbs of crushed oyster shell
1.6 lbs of water

The more cement you use the denser your rock will be.


In the paper they tested if this rock worked as well as traditional live rock at processing ammonia and nitrite - it does!

 

[Nonya]

It can be done, but it won't be porous like the real thing, if that's what you want. Aragocrete has been around for years. No matter what aggregate you use, you need to take action to let it cure long enough so that it won't affect your pH.

 

[inktomi]

In the paper they sort of tested the porosity - water flows through the rock just as well as you might expect it to via traditional live rock.

You can see that in this photo from the paper. It doesn't quite look like "real" live rock, but water does move freely throughout it.

 

[Nonya]

By porous I meant microscopic pores, like in dead coral rock. It's the type that bacteria colonize in large number.

Might I suggest adding perlite? It's porous and inert.

 

[HuduVudu]

Cement leeches things that you don't really want in your tank.

 

[polyppal]

Cement leeches things that you don't really want in your tank.

Yup it’s gonna be algae city if you use a lot of cement, prob significantly more so than normal dry rock.

None of these dry rock alternatives to live rock are doing all that much in the way of bacterial exchange within the rock, a single cube of synthetic biomedia or just the sand bed will contribute multiple times more surface area for bacteria colonization than the rock work

 

[HuduVudu]

Yup it’s gonna be algae city if you use a lot of cement

Indeed.

Was interested so I looked up what is in it specifically.

Fun stuff this:

Cement - Composition, Properties, Major Cements | Britannica

Cement - Composition, Properties, Major Cements: Portland cement is made up of four main compounds: tricalcium silicate (3CaO · SiO2), dicalcium silicate (2CaO · SiO2), tricalcium aluminate (3CaO · Al2O3), and a tetra-calcium aluminoferrite (4CaO · Al2O3Fe2O3). In an abbreviated notation...

www.britannica.com

 

[Garf]

I’ve used cement in my tank, it’s not an issue if you cure it in freshwater for a month with regular water changes.

 

[Rmckoy]

They have been doing this for years .
actually I have roughly 300 lbs of various sized pieces I got about 10 years ago .

to make it more porous they have used rock salt . Which will dissolve when cured in water

making your own with Portland cement , shells and salt . It can be formed in any shape .
but it takes for ever to cure .

 

[inktomi]

Cement leeches things that you don't really want in your tank.

I'm curious! What sort of stuff have you seen? It also I'm sure depends on the type of cement - I learned there are many kinds with different stuff

Perlite is a good idea as something that could be added!

 

[Rmckoy]

I'm curious! What sort of stuff have you seen? It also I'm sure depends on the type of cement - I learned there are many kinds with different stuff

Perlite is a good idea as something that could be added!

Typically … anything I’ve read before Portland cement was used. .