Terrestrial rocks in a reef

[fishguy1978]

I know the correct rock for a reef is "reef rock" and that Fiji and Tonga are the holy grails of reef rock sourcing, at least back when they were available collection locations. Every once in a while my wife and kids ask me to set up a reef again. I haven't done a reef in over 14yrs when I was living in NYC. I have an empty 260g acrylic that to me is an ideal size for a reef. I priced out using 300lbs of dry base rock, 80lbs Fiji pink live sand and 80lbs Fiji pink dry sand about $1000. Still need a skimmer, lights, ro/di system, other reef related filtration stuff.
My wife wanted an answer to why I don't just collect terrestrial rocks like I have for my freshwater setups. I know the one answer buffering of the water column and second aesthetics. I know there are more scientific reasons though and could use some help explaining.
I would rather stick with freshwater though ?

 

[Deadeye]

Various reasons. They can work as decor, but would be essentially functionless. The porous reef rock allows for more surface area for bacteria and I think it buffers ph. It also has certain chemicals that are beneficial to the reef, while terrestrial rock may have harmful chemicals.

 

[fishguy1978]

The porous reef rock allows for ....

Places to stick coral

 

[EntoStentor]

There's no marine microbiome in a terrestrial rock is the short answer.

 

[fishguy1978]

There's no marine microbiome in a terrestrial rock is the short answer.

Right, but I don't know that I would use any "live" rock in the reef structure just dry base. Cost savings only knowing that some coral added will be attached to rock.

 

[Deadeye]

Places to stick coral

Until dealing with bad glue, bulky plugs, and hermit crabs.

Right, but I don't know that I would use any "live" rock in the reef structure just dry base. Cost savings only knowing that some coral added will be attached to rock.

I would put at least some live rock in there, it has its ups and downs, but the pros outweigh the cons imo. It speeds up the cycle and puts plenty of beneficial organisms in the tank. Of course there is a risk of introducing parasites or bad hitchhikers.

 

[BIG-G]

You could possibly use normal rock for a base but you would really gain nothing other saving a little.
You would be losing the ability for water to throughly circulated through and underneath the reef structure creating dead areas for waste to collect, which is a big problem for a reef tank down the line.

Have you checked into the man made version of reef rock and priced any?
I’m not sure of the pricing so it may not be a savings.
I think caribsea makes some.

Back when I reefed I used to make my own base rock with concrete and argonite sand and crushed oyster shell.
You have to soak it for a few weeks to get the Ph down but it was a fun process making the different shapes.

 

[fishguy1978]

You could possibly use normal rock for a base but you would really gain nothing other saving a little.
You would be losing the ability for water to throughly circulated through and underneath the reef structure creating dead areas for waste to collect, which is a big problem for a reef tank down the line.

Have you checked into the man made version of reef rock and priced any?
I’m not sure of the pricing so it may not be a savings.
I think caribsea makes some.

Back when I reefed I used to make my own base rock with concrete and argonite sand and crushed oyster shell.
You have to soak it for a few weeks to get the Ph down but it was a fun process making the different shapes.

I think I saw your diy instructions. I think the weeks of soaking to leach out the bad stuff was a limfac for me

 

[BIG-G]

I think I saw your diy instructions. I think the weeks of soaking to leach out the bad stuff was a limfac for me

I can see that. It takes about a few weeks of daily water changes.
I placed mine in a brute trash can with a power head.
You can speed it up a little by adding vinegar to the water every time you do a change.
Checking the Ph once it gets stable and around 8 you’re good.

 

[Fishman Dave]

Here in the uk there is an alternative which is a man made glass rock. Very porous but have to wear gloves to use it as it rears your fingers. This is often used for structure and support within the reef under real coral rock ( either live or unseeded) as it is a fraction of the price of reef rock. It looks very similar to large alfagrog. This glass rock also quite quickly becomes live when used, especially in a mature tank.

IMO there is no reason the correct none reef rock cannot be used in a reef tank, as long as it is chemically stable. After all, sunken ships, sunken monuments etc are all now often seen as live reefs.
However, you would not expect to get the same biological benefits from land sourced rock as you would from reef rock so may need alternative management and “filtration”.