Old Sand

[haninja]

I broke down my 180 for a redo and disposed of my old sand. This is what my sand looks like after 2 years...

[Mockery]

Did it harden together?

[haninja]

Yep had to chisl it out..

[PFCDeitz]

Lol wow thats some nasty stuff

[DawgFace]

Dear gawd!....... I need to start thinking of how to replace mine!

[LilRobb]

Break it up and throw it in your CA reactor, it's good stuff!

[Mockery]

Why?? What causes that to happen?

[dme330i]

Originally Posted by Mockery

Why?? What causes that to happen?

I think it's caused by precipitation around the sand granules. High Ca and Alk facilitates the process. Within/deep in the sand bed, the pH drops. As the pH drops (similar to a Ca reactor), Ca and Alk dissolve, but then quickly precipiate as the area becomes saturated. When it precipitates it clumps the sand together.

Edit:

Originally Posted by haninja

I broke down my 180 for a redo and disposed of my old sand. This is what my sand looks like after 2 years...

Now that's what I call nutrient export!

[haninja]

Originally Posted by dme330i

I think it's caused by precipitation around the sand granules. High Ca and Alk facilitates the process. Within/deep in the sand bed, the pH drops. As the pH drops (similar to a Ca reactor), Ca and Alk dissolve, but then quickly precipiate as the area becomes saturated. When it precipitates it clumps the sand together.

Edit:

Now that's what I call nutrient export!

That is the best explanation I heard so far .

[mysterybox]

Quote, "
It is reasonably common to have sand harden, especially when new.

It is not entirely clear whether sand bed hardening is a purely physical process involving calcium carbonate deposition (or other minerals) that cements grains together, or whether it is mediated by bacterial processes, but it does not always happen.

It happens most frequently to new sand, and especially when the pH is high (as when using limewater). It happened to me when I first set up my first tank, but not when adding tanks to the existing system using the same type of sand. I would guess that higher alkalinity and calcium also contribute, as well as lower magnesium.

Often the effect disappears as tanks mature (the hard sections stay hard, but unclumped sand stays that way, and new sand won't as readily clump).
The addition of organisms (cucumbers, etc) seems to delay or stop the process as they keep it mixed up and perhaps break tiny links between grains before they become too established.



__________________
Randy Holmes-Farley
Club 65535

end quote"