what causes sand to clump?

[kimba]

I have never seen this before (10+yrs). I don't bring my mag float all the way to the sand bed, so every now and then I take a razor blade and go around the tank at the sand line.

It felt like I was hitting a rock where there was no rock. I pressed and a whole clump of sand came up.
I have a 12 gal tank and 4 sand sifting snails.

Is this really bad, or just really wierd?

 

[cloak]

Check this out.

"I think I have explained this before. In Sedimetentology we call this "Early Marine Diagenesis"

1. The local water in the SB develops a low pH from activity. This causes the dissolution. As dissolution continues the local pH, Alk and Ca++ begin to rise and reaches saturation, causing the precipitation of some CaCO3 around the grains "welding" them together.

2. Fresh new carbonate sands, like in a new tank, are not in equilibrium with the water. This causes the direct precipitation of calcite and often Hi-Magneisum Calcite on the the sand grains surfaces " welding " them together. There are many paper written on this and it is this that is more than likely what is happing in new tanks with new sand bottoms of carbonate sands.

3. Excessive Ca++ Alk and high pH can also cause this, as the sand favors more to precipitation in the SB, which will be even greater if the temp is a little higher there.

The above three produce a cement like clumping structure, where the grains can not be separated without hammer in hand.

4. Certain types of high SB bacterial activity produce organic "slimes / glues" that stick the sand grains together. In this case of SB clumping the grains can be pulled apart. The are more like a sticky gluey mess.



Forgot

Kalk with vinegar or other types of carbon dosing could make this worse where there may be more than one thing going on."

HTH.

 

[saltyfilmfolks]

curious as to what your dosing. Never seen that either.

 

[Joshky]

4. Certain types of high SB bacterial activity produce organic "slimes / glues" that stick the sand grains together. In this case of SB clumping the grains can be pulled apart. The are more like a sticky gluey mess.

I had this one in my old 20 long, didn't know what caused it and now I do. Neat. :D

 

[kimba]

Hmmmm, I got a new tank in Dec and when I switched from old to new I did mix 5 lbs of LS with my old sand (10 yrs old).

The only thing I dose is Kent marine Nano Reef parts A&B. ("Ion and buffer system in proper concentrations for nano reef aquariums)

So it sounds like it's a wierd reaction and not some bad critter in my sand or tank?

 

[kimba]

The sand easily brakes apart in my hand (no hammer needed), but there is no slimy texture to it. Just wet sand

 

[Salty1962]

I've had bacteria cause clumping before in my 90. I broke apart easily though. PH issues could also be causing it.

 

[Wilsoni]

I have several spots in my tank that have developed the same (clumping) that you're experiencing. I've noticed that this has occurred under/around a larger piece such as a scoly or my Wilsoni colony. I have a spot that's developed under my LR as well. It seems like the weight of the rock in combination with some other factor has caused the sand to formulate a solid structure. I'm curious to get a better understanding as well.

Do you have any inverts that live in your sand bed such as Sandsifting Stars or Nassarius Snails?

 

[kimba]

Yes, I have 4 sand sifting snails (12 gal) and nothing on top of the sand. It's also only in the front of the tank, not on the sides. Kinda odd. If it where a ph thing, you would think it would be everywhere.

I'll go test PH

 

[kimba]

PH is between 8.0 and 8.2

 

[kimba]

And not sure if it matters, but I just did a 2 gal WC (that's how I found the clumps)

 

[saltyfilmfolks]

interesting.
@cloak I would assume the only way of determining what the cause is to look at samples under a microscope. If its a mineral deposit it should appear crystalline, and if its bacterial it should appear to be stringy filaments.

By local water I belive Mr Cloak means the water in and directly on the sand. as the electrons in the sand molecules are charged keeping a layer charged particles close to the sand as it reacts to the ions in the water during buffering giving it a higher or lower PH, and a PH test is only sampling overall tank water PH and not the tiny "micro climates" around on or in the sand.
That being said, your sand and rock for that matter the flesh of a coral is not really the same PH as the water sample your testing with your kit.
Weird right?

 

[kimba]

Yes, that is wierd. Never thought of it like that.

So do I have to DO anything?

 

[saltyfilmfolks]

Yes, that is wierd. Never thought of it like that.

So do I have to DO anything?

Dunno.

If it was me, keep eyeballing the sand. Its possible its precipitate from the two part falling in that spot, Like cyano settling in lower flow, or cyano falling in spots of highest flow because its constantly hit with fresh supply of nutrients.

 

[kimba]

Sounds good, thanks everyone!!

 

[SteveL99]

Check this out.

"I think I have explained this before. In Sedimetentology we call this "Early Marine Diagenesis"

1. The local water in the SB develops a low pH from activity. This causes the dissolution. As dissolution continues the local pH, Alk and Ca++ begin to rise and reaches saturation, causing the precipitation of some CaCO3 around the grains "welding" them together.

2. Fresh new carbonate sands, like in a new tank, are not in equilibrium with the water. This causes the direct precipitation of calcite and often Hi-Magneisum Calcite on the the sand grains surfaces " welding " them together. There are many paper written on this and it is this that is more than likely what is happing in new tanks with new sand bottoms of carbonate sands.

3. Excessive Ca++ Alk and high pH can also cause this, as the sand favors more to precipitation in the SB, which will be even greater if the temp is a little higher there.

The above three produce a cement like clumping structure, where the grains can not be separated without hammer in hand.

4. Certain types of high SB bacterial activity produce organic "slimes / glues" that stick the sand grains together. In this case of SB clumping the grains can be pulled apart. The are more like a sticky gluey mess.



Forgot

Kalk with vinegar or other types of carbon dosing could make this worse where there may be more than one thing going on."

HTH.

Thanks for this information. I saw your post on this topic on Reef Central as well. I have a new tank and am getting very hard clumps that I can breakup in my hand, but just barely. The SB is brand new and I'm dosing 2 part, so I'm probably #2 in your answer above. My question is should i just keep dosing and eventually it will find equalibrium? I'm dosing almost double the manufacturers recommended starting point. I'm doing this because my Alk wouldn't stay above 7.2. Once I started dosing this much, my Alk has been pretty steady above 8.5, but my Calc is now below 300 and it seems like the more I dose the more clumps I get, but not increase in calcium. The tank is 8 weeks old and I started dosing about 5 weeks ago. Should I cut my dosing, or just wait for things to even out?