Reverse solidified sand

[chimbo84]

When I first started my tank, I was running my alkalinity at 9.0dKh. After a few weeks, I noticed that the Carib sea special grade had started to clump together and form aggregate rocks so to speak.

For other reasons, I have recently dropped my alkalinity to 8.3 and noticed that all of my sand is now basically one giant slab and my rockscape is stuck to it. I am unable to move most of the rocks in my tank and sand dwellers have only a couple pockets of granular sand where they can go.

my question is if there is a safe way to reverse this process? I assume lowering my pH might help (currently ranges 8.2-8.35) but I’m not sure if this is safe.

my sand has so little turnover that I actually have coralline growing on it in spots.

 

[Alexopora]

Just throwing an idea here, how about getting something long and sturdy to mash up the sand.

 

[homer1475]

Not sure there is a way to reverse it. I never found one. Had to remove it all and add new.

If your sand is turning like rock, your overdosing.

You should just stop dosing all together for a few days and let things settle, then measure for a couple days before resuming your dosing.

@Randy Holmes-Farley might have an answer for reversing it?

I would assume your dosing soda ash, you could switch to sodium bicarbonate to help with the solidifying sand.

 

[chimbo84]

Just throwing an idea here, how about getting something long and sturdy to mash up the sand.

I have tried. I have a fiberglass rod that I tried to smash it up with but it’s quite hard in a lot of spots and I am worried about cracking the bottom glass if it suddenly gives way.

 

[chimbo84]

Not sure there is a way to reverse it. I never found one. Had to remove it all and add new.

If your sand is turning like rock, your overdosing.

You should just stop dosing all together for a few days and let things settle, then measure for a couple days before resuming your dosing.

@Randy Holmes-Farley might have an answer for reversing it?

I would assume your dosing soda ash, you could switch to sodium bicarbonate to help with the solidifying sand.

I have been dosing kalkwasser but switching to bicarbonate would achieve what? Lower pH? I guess my question is if I can accomplish that without changing my dosing regime.

 

[Hans-Werner]

I have been dosing kalkwasser

Kalkwasser is wellknown for solidifying sand bottoms. 9 KH is very high for kalkwasser, I think normal is rather 6 to 7 KH for kalkwasser at "normal" calcium concentrations.

The reason is most likely the amount of kalkwasser you have to add for keeping 9 KH. High alkalinity and high pH from kalkwasser addition causes these sand hardening by calcium carbonate precipitation in the sand layer.

 

[chimbo84]

Kalkwasser is wellknown for solidifying sand bottoms. 9 KH is very high for kalkwasser, I think normal is rather 6 to 7 KH for kalkwasser at "normal" calcium concentrations.

The reason is most likely the amount of kalkwasser you have to add for keeping 9 KH. High alkalinity and high pH from kalkwasser addition causes these sand hardening by calcium carbonate precipitation in the sand layer.

Dang. It sounds like the damage is done then. I’m sort of lost as to how to fix this. Replacing the sand bed is likely to dramatically disturb my tank and even then, to do so will require me to break down my entire rock scape. I think I would essentially be starting over.

Any suggestions?

 

[homer1475]

I did it and didn't really start over.

Removed the rock, caught the fish, put them in a tub with a heater and PH. Chisseled off the sand from the rock, replaced the rock, added new sand.

Was pretty simple really. Took me a good day to get it all back up and running, but wasn't too bad.

Pics of my rock hard sand:

 

[Jonify]

You won't be able to safely lower your pH enough to dissolve the carbonate in your sand; the best course of action is just to stab the sand with a long plastic tool to break it up. I've been there. In my case, all the carbonate I was dosing would just go straight to the sand bed without raising my alkalinity level. I would keep trying to raise, dose more, but it wouldn't budge, it would just harden my sand bed. I swapped to bicarbonate and that fixed my issues; I think this occurs more in less established tanks.

 

[Nano sapiens]

Well known issue that only happens to relatively few reef keepers.

Whether it's more prevalent for those that use Kalkwasser, I couldn't say. What I do know is that having used Kalkwasser exclusively for nearly 40 years I've never had any solidification of a sand bed, so it's not something that occurs automatically with Kalkwasser usage.

Some believe that this condition may be biological in nature. Bacteria are known to secrete polysaccharides, polyamides, polyesters and inorganic polyanhydrides that can potentially bind a substrate into a solidified matrix.

Replacement may be the best option...

 

[Enderg60]

Man when that used to happen in my old tank Id just break it up in my hands while I had my hands in there. They were never hard to break back down to sand. But I was using 2 part not Kalk.

 

[homer1475]

I never used Kalk either, just straight up 2 part(soda ash). Mine you could not break up unless you used a chisel and hammer. It was literally hard as a rock!

Switched to sodium bicarb and never had the issue again. I do dose soda ash now as opposed to sodium bicarb, but I have heard @Randy Holmes-Farley mention many times to switch to sodium bicarb to help alleviate the issue.

 

[Nano sapiens]

Man when that used to happen in my old tank Id just break it up in my hands while I had my hands in there. They were never hard to break back down to sand. But I was using 2 part not Kalk.

From what I've read/seen, it is likely that there are multiple mechanisms for 'substrate hardening'. Some produce a rock solid mass and some more of a 'clumping' that can be relatively easily broken up with the hands. Speculation, but if I had to guess I'd say the rock solid mass is likely caused by a chemical process and the friable mass is biological in origin (some sort of living or life-produced organic matrix).

 

[Reefahholic]

Kalkwasser is wellknown for solidifying sand bottoms. 9 KH is very high for kalkwasser, I think normal is rather 6 to 7 KH for kalkwasser at "normal" calcium concentrations.

The reason is most likely the amount of kalkwasser you have to add for keeping 9 KH. High alkalinity and high pH from kalkwasser addition causes these sand hardening by calcium carbonate precipitation in the sand layer.

:-)
Photo Credit: ReefBum

 

[chimbo84]

:)
Photo Credit: ReefBum

Oh jeez. I’m really not looking forward to dealing with this. What a mess.

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, I removed some hard chunks early in in my system, but as is often the case, the tendency to harden sand is much more prevalent with new and dead sand that presumably lacks a protective coating of magnesium/phosphate/organics which prevents the sand surfaces from acting as seed crystals for precipitating more calcium carbonate onto them.