Soft/crumbly part on rock?

saltcats · May 18, 2023

Apologies if this has been covered before but search results didn't turn up much useful - I have been cycling some dry rock in a bucket of saltwater for a few days now. Picked one of them up today and noticed a very soft/crumbly area on it? The rest of the rock seems normal but this one patch I can easily dig away at with my fingernail.

Is this normal or should I be concerned? Should I just try to scrape off all the crumbly part (hopefully it doesnt go all the way through...) before I use it? Thanks!

I don't know the "brand" of the rocks, just what my LFS carries. They look similar to marco rocks.

Timfish · May 18, 2023

Kinda depends on the rock. If it was like "Life Rock" it's concrete and soft spots might be poorly mixed and cause pH issues. I use local limestone alot and occasionally find spots like you're describing. I'll remove most of the soft stuff with my finger or a screwdriver and use it without worrying about hosing it all off. If it's rock from an oceanic source I'd do the same as I would local limestone, it's probably some boring sponges or endoliths that have dissolved some of the carbonates

saltcats · May 18, 2023

Timfish said:
Kinda depends on the rock. If it was like "Life Rock" it's concrete and soft spots might be poorly mixed and cause pH issues. I use local limestone alot and occasionally find spots like you're describing. I'll remove most of the soft stuff with my finger or a screwdriver and use it without worrying about hosing it all off. If it's rock from an oceanic source I'd do the same as I would local limestone, it's probably some boring sponges or endoliths that have dissolved some of the carbonates

Hmm.. It's not "life rock" per se but I suspect it's probably manmade rather than natural limestone. Shame because it's a pretty shaped piece. Do you think if I keep soaking it in saltwater and test the pH after a week or so that'll give me an idea if it's going to be a problem? I'll try and remove as much of the soft part as I can.