Rocks shrinking

Salty Rambler · Dec 4, 2023

My rockwork is slowly eroding. Looking back at pictures, the first few years showed no changes, but over the last year, the rockwork has lost circa a third of its mass. Does anyone have a similar experience?

FoolishWizard · Dec 4, 2023

Before / After shots?

Uncle99 · Dec 4, 2023

What’s your DKH run at.
Maybe it’s lower than 7.
If your water is acidic, rocks can erode.

Dan_P · Dec 4, 2023

Salty Rambler said:
My rockwork is slowly eroding. Looking back at pictures, the first few years showed no changes, but over the last year, the rockwork has lost circa a third of its mass. Does anyone have a similar experience?

Pictures would help. I assume this aragonite not a synthetic material.

Mr. Mojo Rising · Dec 4, 2023

how long the rocks been in the tank?

VintageReefer · Dec 4, 2023

Do you have an urchin?

Salty Rambler · Dec 4, 2023

VintageReefer said:
Do you have an urchin?

I have a long spined urchin that has been in the tank 6+ years.

Salty Rambler · Dec 4, 2023

Mr. Mojo Rising said:
how long the rocks been in the tank?

The rocks are original to when I took over the tank from the prior owner, so probably 7 or more years. As far as I can tell, they were purchased from a LFS in Florida.

WhatCouldGoWrong71 · Dec 4, 2023

My man made rocks have cracked and had chunks fall off of them from time to time. But, I e not seen erosion at all.

Salty Rambler · Dec 4, 2023

Dan_P said:
Pictures would help. I assume this aragonite not a synthetic material.

The top photo is Christmas last year, with the rockwork looking the same as it had previously. The bottom photo is a close in current shot of the same bridge rock, vastly reduced in size.

Salty Rambler · Dec 4, 2023

Uncle99 said:
What’s your DKH run at.
Maybe it’s lower than 7.
If your water is acidic, rocks can erode.

Last I checked the DKH was fine, but I haven't checked it in the last few weeks. I'm finishing up a 48 hour chemiclean treatment and water change tonight, but after I let it settle for a few days, I'll check the DKH again.

Salty Rambler · Dec 4, 2023

WhatCouldGoWrong71 said:
My man made rocks have cracked and had chunks fall off of them from time to time. But, I e not seen erosion at all.

I haven't seen anything on the forums about it either, so I'm stumped. Maybe there is a deficiency in my tank water, but it isn't showing up in tests because it is being pulled/replaced from the rocks.

VintageReefer · Dec 4, 2023

Salty Rambler said:
I have a long spined urchin that has been in the tank 6+ years.

Sea urchins chew and erode rock away. It happens as they clean the rock. They take off very light layers and eventually over time this becomes noticeable

Ask me how I know? I had a long spine urchin in a tank for years and noticed the same thing as you. I asked if you had an urchin and I felt I already knew you must if this is what you are experiencing

VintageReefer · Dec 4, 2023

Facts:

Sea urchins can drill holes in solid rock with just their teeth

If a sea urchin can't find a suitable pit to live in, it makes one – even if it has to spend months gnawing away at hard granite

www.newscientist.com

And

Living on Earth: Science Note: Sea Urchins Eat Rocks

Sea urchins help create their own homes by chewing up the rocks they live on. As Aynsley O’Neill reports in this week’s Note on Emerging Science, Purple sea urchins can create as much sediment as a river would deposit.

loe.org

Salty Rambler · Dec 4, 2023

VintageReefer said:
Sea urchins chew and erode rock away. It happens as they clean the rock. They take off very light layers and eventually over time this becomes noticeable

Ask me how I know? I had a long spine urchin in a tank for years and noticed the same thing as you. I asked if you had an urchin and I felt I already knew you must if this is what you are experiencing

This brings a lot of mixed feelings. It would be great to learn it isn't user error, but the urchin has called the tank home for far longer than I've been it's caretaker. It is going to outgrow the tank eventually, but I've been delaying rehoming it.

Did you remove your urchin? If so, what did you add in its stead?

VintageReefer · Dec 4, 2023

I gave to lfs. A 8” mobile pincushion was damaging corals and breaking off spine tips all over

I did like him though. Super cool creature

I don’t even have that tank anymore. It was a impulse buy when I first got into sw tanks.

Maybe keep eye out for a Petco tank on sale or a used one on fb market and give him his own place to town around one day. A 40 breeder would be good

Midrats · Dec 4, 2023

Add more rock

blecki · Dec 4, 2023

Yeah just give him more rock to munch on. My pincushion has slowly been turning my rock into sand for almost a decade now. Spread the damage out more and you won't ever notice it!

Salty Rambler · Dec 5, 2023

Midrats said:
Add more rock

More rock is definitely on the agenda -- just need to figure out placement so that the rest of the structure is stabilized.

V_Sh · Dec 5, 2023

Salty Rambler said:
The top photo is Christmas last year, with the rockwork looking the same as it had previously. The bottom photo is a close in current shot of the same bridge rock, vastly reduced in size.

Hi,

I have no experience with man-made things as they are not available in my region, but I have erosion experience with natural live-rocks.

some worms seem to dig in the rock like drills and pull out dirt, but does not seem to be your problem; although I guess I'm seeing bristle worms on your rocks.

also, urchins kinda turn the rocks into powder.

The best way I suggest is to try building up coralline algae on your rocks and to pull out animals which chew the rocks

also, the pH and KH are not the problems, the pH that dissolves carbonates gonna kill all the marine animals, and a low KH will result in not building up Coraline or coral skeletons which are not your problems.