Live rock on eggcrate, sand or on bottom?

Reefer Rob · #1 01-13-2012, 03:49 PM

Has anyone actually heard of rock falling and breaking a tank bottom? I wouldn't think it likely, they fall in slow motion in the water... but you never know. I think a piece of 1/8" Plexiglas would be better than egg crate if you're worried about your glass.

I would still raise the back of your rock up on stilts to get flow across the bottom of your rock. Any rock surface buried in sand is wasted. Leave the door open to go bare bottom if you find your nutrient levels aren't where you want them.

lastlight · #2 01-13-2012, 03:52 PM

I highly doubt it's possible in reefing. You either have manageable sized rocks in a smaller thinner-bottomed tank or you have massive boulders with a 19mm bottom or thicker. I can't see it happening and the risk at the very worst can't be great.

I did drop a rock and blow the bottom of my frontosa tank out back in the day though. They were juvies and the tank was only a 45 gallon. Difference being I was using heavy rundle rock slabs. Our rock is WAY lighter you're right.

So yeah rock right on glass. I'd consider pegs of some sort if they're short to elevate the rock but I'd never do it with eggcrate.

jtbadco · #3 01-13-2012, 05:35 PM

intarsiabox · #4 01-13-2012, 05:39 PM

Quote:

Originally Posted by jtbadco

It's not rock falling and breaking the glass that you need to worry about. It is having all the weight of the rock above focused on the tank bottom thru one grain of sand.

If even one grain of sand gets between the LR and the glass bottom it can focus all the weight above onto that one spot.

Not worth the risk IMO.

Here's a quick calculator...

$10 for eggcrate or oyster shells (in my case) divided by cost of broken tank, loss of all inhabitants...fish, corals, LR, damage to house, floors and hassle of clean up.

Easy math

So what happens if one grain of sand gets between the egg crate or oyster shell and glass?

lastlight · #5 01-13-2012, 06:10 PM

Quote:

Originally Posted by intarsiabox

So what happens if one grain of sand gets between the egg crate or oyster shell and glass?

Oh SNAP!

Reef Pilot · #6 01-13-2012, 06:21 PM

Reminds me last year when I was installing a new light fixture for a bathroom. It was on a full wall mirror, and got the old one off, no problem, and the new one fitted on nicely. But then I was tightening (just one more little bit of a turn) up the rear back plate that was against the mirror through a drilled hole to the wall,...I heard this horrible snap, and a big crack ran out from under the back plate.

Had to pull off the whole mirror which was glued to the wall, piece by piece, and using a hammer to break more pieces to get it off.

That was not a good day....

lastlight · #7 01-13-2012, 06:24 PM

Quote:

Originally Posted by Reef Pilot

Reminds me last year when I was installing a new light fixture for a bathroom. It was on a full wall mirror, and got the old one off, no problem, and the new one fitted on nicely. But then I was tightening (just one more little bit of a turn) up the rear back plate that was against the mirror through a drilled hole to the wall,...I heard this horrible snap, and a big crack ran out from under the back plate.

Had to pull off the whole mirror which was glued to the wall, piece by piece, and using a hammer to break more pieces to get it off.

That was not a good day....

How did sand get back there?

Aquattro · #8 01-13-2012, 05:50 PM

Quote:

Originally Posted by jtbadco

It's not rock falling and breaking the glass that you need to worry about. It is having all the weight of the rock above focused on the tank bottom thru one grain of sand.

If even one grain of sand gets between the LR and the glass bottom it can focus all the weight above onto that one spot.

Not worth the risk IMO.

Here's a quick calculator...

$10 for eggcrate or oyster shells (in my case) divided by cost of broken tank, loss of all inhabitants...fish, corals, LR, damage to house, floors and hassle of clean up.

Easy math

I'm sorry, but that fringes on ridiculous. The rock is not going to focus it's mass on one grain of sand and break glass. ""IF"" it focused that much mass on a single grain of sand, the sand will crush. Or it will puncture into the bottom of the rock. Or get squeezed out sideways.

I have always laid my rock on bare glass. I've dropped 5 pound pieces of rock in the tank (with water) and had it hit glass. The eggcrate is not dispersing weight to save glass. Just not happening. My holding tank has 3/8" glass on the bottom, I filled it for months with 140 pounds of rock that I flipped and flopped around while rummaging for certain pieces.

Here's an example. I needed to remove a cross brace from a tank. Figured a hammer was the quickest way. It was utterly amazing the force I had to hit it with to actually break it. A rock tumbling 8 inches in water to rest on your glass is not going to break anything but corals.

I have seen once, and only once, where a rock, about 40 pounds, fell 2' in huge tank and actually broke the bottom.

jtbadco · #9 01-13-2012, 06:04 PM

Aquattro · #10 01-13-2012, 06:10 PM

Quote:

Originally Posted by jtbadco

I never said it would for sure happen. I don't know everything. IMO it's not worth the risk. Feel free to do what you like.

Sorry, I didn't mean to sound harsh, but that is one scenario that can't happen. Both the rock and the sand are softer than the glass, and either will give before the glass.