Rock hard crushed coral sand bed

[mosseo]

I tore down my 120gal salt tank and now well over half the tank is 2” ‘s of rock-hard crushed coral. Large chunks of base rock are also infused within it.
I used to dose 55ml of powdered Red Sea Alkalinity and 25ml of powdered Red Sea Calcium.
Any suggestions on how to remove it without using a chisel? I’m trying to soak it in straight water but so far it hasn’t made any difference.

Thanks

 

[wvned]

Your only other option would be to dissolve it with an acid like vinegar or muriatic acid. They have 30% vinegar at Home Depot.
I would add water until it is covered by a couple of inches and then add 1/2 gallon of the vinegar and let it sit.
Or
remove as much of the water as you can and pour the vinegar across it in a strip and try to weaken spots enough to break it up.

 

[griss]

Your only other option would be to dissolve it with an acid like vinegar or muriatic acid. They have 30% vinegar at Home Depot.
I would add water until it is covered by a couple of inches and then add 1/2 gallon of the vinegar and let it sit.
Or
remove as much of the water as you can and pour the vinegar across it in a strip and try to weaken spots enough to break it up.

This is what I would recommend as well.

 

[mellotang]

Any theories as to what causes this?

I have encountered it in tanks with high PO4
Not sure if PO4 bound up in crushed coral n had some reaction with calcium carbonate n became solid

 

[griss]

Any theories as to what causes this?

I have encountered it in tanks with high PO4
Not sure if PO4 bound up in crushed coral n had some reaction with calcium carbonate n became solid

I’m not very good with chemistry but, I thought it was due to higher than normal Alk.

 

[Jimbob]

From my understanding of chemistry, griss is spot on here. A sand bed, whether in marine aquaria or in nature can become solidified due to either bacterial activity, mineral precipitation, or a combination thereof. Mineral precipitation often occurs due to high pH caused by elevated alkalinity levels. This can be exacerbated by disruptions to the sand bed where a combination of high pH + bacteria interact to effectively glue the sand bed grains to one another.

 

[Reefing102]

From my understanding of chemistry, griss is spot on here. A sand bed, whether in marine aquaria or in nature can become solidified due to either bacterial activity, mineral precipitation, or a combination thereof. Mineral precipitation often occurs due to high pH caused by elevated alkalinity levels. This can be exacerbated by disruptions to the sand bed where a combination of high pH + bacteria interact to effectively glue the sand bed grains to one another.

Interesting.

I had always thought of it of the opposite (though I have no research to back it up) where a low pH causes slight dissolution of the crushed coral to maintain the pH and then rehardens once pH elevates again. Again no research or anything like that, just what I always thought.

 

[griss]

Interesting.

I had always thought of it of the opposite (though I have no research to back it up) where a low pH causes slight dissolution of the crushed coral to maintain the pH and then rehardens once pH elevates again. Again no research or anything like that, just what I always thought.

Maybe my thinking is backwards and you’re correct. Like I said, I’m not terribly chem oriented and I’m trying to get sick so, I could be misremembering.

 

[Jimbob]

Interesting.

I had always thought of it of the opposite (though I have no research to back it up) where a low pH causes slight dissolution of the crushed coral to maintain the pH and then rehardens once pH elevates again. Again no research or anything like that, just what I always thought.

More likely too high of alk and/or high pH.

Ron Shimek posted on this several times (can't seem to find the links.

There are other resources out there.

This from Boston Reefers: What causes sand to turn into a brick?

This old thread from here on RC wherein RHF addresses it: https://www.reefcentral.com/forums/showthread.php?t=617728

Another old RC thread: https://reefcentral.com/forums/showthread.php?t=1864522

Or this one: https://www.reefcentral.com/forums/showthread.php?t=1964684

The most common theme is high pH, High Alk, and/or other high amounts of precipitating elements.