how to avoid clumping

[reef tank 2.0]

As I was trying to catch the remaining fish last night in my tank, I was moving rock around in order to do so. When I got to the rock that was the base of the structure, I found they were very hard to move. The more I pulled, and pried, and worked it, it finally broke loose. What was once a two handed sized piece of rock, ended up being a slab of sand/other rocks near by. That was crazy! I eventually broke it apart, but many rocks still have this solid mass of sand stuck to it. I'll chip it all off when it comes time to clean the tank (this weekend).

My questions: I assume this is a calcium build up of some sort, maybe? How exactly can/do you avoid this from happening? Certainly makes it hard if you'd like to re-aquascape at any point down the road. When I set it up again, I thought about placing the egg crate under the rocks, then sand on top of that. But wouldn't I still run in to the same problem, but this time, it would really be one large mass of rock/sand/egg crate.

Anyone else deal with this?

 

[mcgyvr]

Known and somewhat fairly common issue..
Plenty of assumptions and intelligent potential causes by some of the smartest forum members that were once here..

Never seen a "this is how you prevent it" proven/guaranteed solution..

 

[outssider]

switch from carbonate based alkalinity to bicarbonate based alkalinity additive

 

[Stevolough]

When I had a issue with that I was dosing two part in my sump which really isn’t the high flow area they say to ad it. And even though my numbers were stable I was adding more than I needed to.

 

[mattgumaer]

I would add that it may be possible to keep sand 'loose' by having things that live in and/or move the sand around like cucumbers, conches, burrowing shrimp/fish, sand sifters, etc.. However, depending on what you buy and your particular tank, some things that rely on the sand bed for food could starve.

Matt

 

[Rip Current]

Sound like a good way to make live rock!!

 

[Kevin Guthrie]

Solid mass in my tank, I use both a CA reactor and a kalk reactor. I was unable to move one of my rocks due to this. Close look revealed strandy white hairs on the broken edges of the gravel bricks, not sure what that was or whether it was responsible for the bricking up.