Rock weight in aquariums

[Marvelous]

Hi I just recently found a bunch of cool rocks that I thought about putting in an aquarium (kind of a wall effect). I was just wondering if anyone knows the lbs per gallon ratio? I wouldnt think they could hold that much weight but i have heard of people putting 300lbs of live rock in their tanks before.

Thanks
Marv

 

[meegosh]

I don't think there is a weight limit... well I'm sure there is but it is probably ridiculous. A lot of people will put egg crate below the rocks, then pour the substrate around it. This prevents your fish from burrowing under the rocks and toppling them over into your glass. You do not want that happening. If you only have a few pounds of rocks, you could probably get away with putting them right on the glass and then pouring the substrate around it.

 

[CaptainAhab]

Saltwater tanks have up to (and more) 3 lbs per gallon of live rock. So a 50 gallon SW might that 150 lbs of live rock..

 

[Marvelous]

what about freshwater tank

I am using a freshwater tank. Would that make difference on how much weight I could use? And I guess I dont totally understand the egg carton thing. Do you have any pictures of this process or know where I could go to see how its done, sounds interesting.

Thanks
Marv

 

[gzeiger]

Tank construction is the same between fresh and salt, so the weight loads you can have are the same. Water already weighs 8lb/gal. Rock is denser, but not tremendously so, and there's a considerable safety margin built into the glass. I doubt you'll get anywhere near the limit before you get tired of the rock pile obstructing your view of the fish.

The egg crate (not the same as egg carton - it's basically a hard plastic mesh) would be for the purpose of evenly distributing the weight of the rock across the entire tank bottom rather than having it rest on just a few points of contact. Essentially any hard flat surface would do, but egg crate is a lightweight material and known to be aquarium safe. It just serves to support the rock, distribute weight, and absorb shock if the rock shifts.

 

[CaptainAhab]

You'll find it in the 'drop ceiling' section of your local HD/Lowes. It's used for light diffusing in drop ceiling. Ever see those silver grates in drop ceilings in offices.. Small 3/4" or so squares of either 4x4 or 2x4 size? that's it.. They come in white, easy to find fairly cheap, silver (reflective) expensive and black (very hard to find). You put that on the bottom of the tank and put your sand/gravel over it. If you pile your rocks up and one of them happens to fall the eggcrate will disperse the impact somewhat and lessen the likelihood that the bottom on your tank cracks or breaks.

Mostly used in SW since we have vast amounts of live rock piled up. But if you are going to stack rocks for effect it's a good choice. A 2x4 section should cost you no more than $8-10.. Good insurance if you're piling.