Fresh water rock

[Freenow54]

I have a lot of rock left from my freshwater days. Has anyone tried using it in a saltwater tan? Could you use it?

 

[ISpeakForTheSeas]

It has been done with a variety of freshwater rocks, and it can be used (lots of people report no problems; some people report bad algae for a while):

This has been a controversial topic the few times I've seen it come up - long story short, I've never seen a tank crash (i.e. with things dying in it) from the use of lava rock; I have, however, seen lava rock taken from a freshwater setting and reused in a saltwater setting that had major algae problems for about a year (presumably from built up nutrients and/or iron in the rock).

That said, in theory (I've never seen this actually proven to happen in practice), lava rock can leach toxic metals into the water, so to responsibly use it, most people cure it for a decent length of time (several weeks; preferably with RO/DI water because you know it's not adding anything unwanted to the mix).

Edit: To add one more point to consider: volcanic/lava rock lacks the pH buffering abilities of calcium carbonate rock.

Nope. I used seriyu rocks and never had issue other then they got ugly once things started growing on them.

 

[JNalley]

As a general rule, you don't want to. Saltwater rocks we use in our tanks are composed of Calcium Carbonate which help maintain a high pH. The rocks are also extremely porous allowing heavy colonization of bacteria deep within the rock aiding in the Nitrogen Cycle within a reef tank.

By contrast, Freshwater rocks are often dense, lack porosity, and are made of silicates, Iron, and other things including metals that are not desirable within a saltwater tank environment. This can lead to algae and many other things.

Also, if you ever treated your tank with copper, this is likely stored within the rocks which could leech back out, killing any of your saltwater invertebrates

 

[Slocke]

I have a lot of rock left from my freshwater days. Has anyone tried using it in a saltwater tan? Could you use it?

Research what the rocks are made of. Many freshwater rocks are calcium carbonate just like saltwater rocks so will be just as good. Though they have a little less surface area.

Seriyu stone is just fine (never had a silicate issue despite the veins). Lava rock is not calcium carbonate so will not help your alkalinity but is nice and porous for bacteria growth. Have not tried other common fresh water rocks.

 

[JNalley]

Research what the rocks are made of. Many freshwater rocks are calcium carbonate just like saltwater rocks so will be just as good. Though they have a little less surface area.

Seriyu stone is just fine (never had a silicate issue despite the veins). Lava rock is not calcium carbonate so will not help your alkalinity but is nice and porous for bacteria growth. Have not tried other common fresh water rocks.

Which other brands are Limestone? I know Seiryu is, but most of the freshwater rocks I come across are some type of igneous rock, Lava Rock, Slate, etc... Wolf Stone (from images) looks like a conglomerate, so it has limestone or some other sedimentary rock binding together other pieces of different rocks... I'm not saying you're wrong, I am just curious, I don't really take part in the Freshwater side of the hobby, and only occasionally help friends with their fresh tanks...

 

[Slocke]

I believe lava and slate don’t leach (though lava rock sometimes has other constituents that do.)
Seiryu is calcium carbonate with veins of silicate. I know people say silicates cause diatoms but I never had more then the briefest and lightest diatoms on my tank with 150lbs of seiryu.

Haven’t tried other things. I’d also say that most of the artificial reef rock we get is unfortunately not porous. Caribsea rocks for example seem to have little to know perosity compared to real reef rock as you can easily tell by its density

 

[JNalley]

I believe lava and slate don’t leach (though lava rock sometimes has other constituents that do.)
Seiryu is calcium carbonate with veins of silicate. I know people say silicates cause diatoms but I never had more then the briefest and lightest diatoms on my tank with 150lbs of seiryu.

Haven’t tried other things. I’d also say that most of the artificial reef rock we get is unfortunately not porous. Caribsea rocks for example seem to have little to know perosity compared to real reef rock as you can easily tell by its density

CaribSea "LifeRock" is that way, their Moani is mined rock like Marco rocks and a couple of others. I prefer the Moani to all of them, when I do a dry rock tank it's the rock I go for typically. Though, now that Real Ocean Harvested live rock is back in the mix (Not Maricultured rock like TBS and others) I generally lean towards that route...