Dry rock dissolving?

[digitlhaze]

Heya folks, another newbie question here...so when I set up my tank a couple of months ago, I went about half live and half dry rock. Looking back, the dry rock wasn't labeled with exact what type of rock it was and now it seems to be... dissolving?

I was pulling some hair algae off of one of the pieces and my finger just sort of...went through it. So I started hitting it with a turkey baster and it looks like I'm just sort of blowing rock dust away.

I'm going to replace this with more live rock soon, but my question is how big of an issue is this? I can't get to my lfs for a few days still, and don't know if I should leave it in any longer or if I need to get it out now.

I've also been seeing my phosphates and nitrates are pretty high and don't know if this could be part of that or not, I'm not really chasing numbers yet since the tank is still so fresh. Last water tests, all with Salifert (ammonia/nitrite at 0):

 

[tbrown]

I've seen rock become brittle after being in the aquarium for a few years. My theory is that the water is stripping the minerals from the rocks if the water isn't kept up through dosing or water changes.

 

[tbrown]

@Randy Holmes-Farley

 

[Randy Holmes-Farley Verified Community Expert]

It’s hard to know if it is an issue without knowing what the rock is, and an lfs may not really know.

Alk rising is a common concern, but that seems to not be an issue. It is probably just mostly crumbling, as opposed to actually dissolving in large amounts.

No natural rock (without dead organisms on it) will release nitrate. I would not assume either N or P is coming from it, but phosphate cannot be definitely ruled out.

fYI, the magnesium result is likely a test error, and it is likely much higher. I don’t recommend testing it at home.

 

[digitlhaze]

It’s hard to know if it is an issue without knowing what the rock is, and an lfs may not really know.

Alk rising is a common concern, but that seems to not be an issue. It is probably just mostly crumbling, as opposed to actually dissolving in large amounts.

No natural rock (without dead organisms on it) will release nitrate. I would not assume either N or P is coming from it, but phosphate cannot be definitely ruled out.

fYI, the magnesium result is likely a test error, and it is likely much higher. I don’t recommend testing it at home.

I know the home mg tests aren't great, I was just sort of using them to see if whatever reading they give is at least stable.

The nutrients are probably just me overfeeding, so I've cut that back a bit as well.

But as long as nothing should blow up horribly in the next few days I'll just leave them in for now and swap them with some new live rock next week - I wish I hadn't glued zoa frags to it now though haha. Hopefully it will just crumble when I go to pop them off.

 

[Abyssara]

Do you remember the brand of rock? Are you able to post a picture or a video? What is your pH?

 

[digitlhaze]

Do you remember the brand of rock? Are you able to post a picture or a video? What is your pH?

It was unbranded, just sort of a "bulk bin" of dry rock at my lfs, I can get some pictures later on. Ph was around 8.3 last I checked, but admittedly I don't have the best test for that - I don't entirely trust my eyes to match colors perfectly

 

[Abyssara]

It was unbranded, just sort of a "bulk bin" of dry rock at my lfs, I can get some pictures later on. Ph was around 8.3 last I checked, but admittedly I don't have the best test for that - I don't entirely trust my eyes to match colors perfectly

I wouldn't expect calcium carbonate dissolution this quickly. It happens but over a long period. I'd imagine this is more of a mechanical breakdown than a chemical one.