# WEIGHT OF ROCKS AND DISTRIBUTION



## Dobbs92 (Dec 15, 2008)

Hi all, I'm just in the planning stages of what was to be a 75 gal. Malawian tank and which has now become a 125 gal. Two questions: 1) Does anyone know what is a safe weight limit for rocks in this size tank? I can get lace rock locally but the cost may be prohibitive so I'm planning on spending some time collecting my own and also visiting local landscapers. 2) I've read that rocks should be placed on thin styrofoam sheets to evenly distribute the weight. Is there any particular type of styrofoam that is aquarium safe or can I just pick up the type that is available from Home Depot or the local craft store? Thank you in adavnce for any help that you can provide.


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## Joea (May 25, 2004)

You won't have enough room in the tank for the amount of weight in rocks it would take to break it. Tanks are designed to take tremendous amounts of weight. Eggcrate or styrofoam will help protect against falling rocks, but will do nothing to protect it from weight.


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## Johnnyboy (Oct 1, 2008)

its not styrofoam, its egg crate. You can find it at home depot, lowes, etc...

as far as weight, someone linked a youtube video where someone stacked rocks about 3-4 feet high outta his tank and then stood on top of the pile. long story short the tank didnt break, no cracks, nothing. so i dont think you can fit enough rocks in the tank to do any damage to it 

HTH


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## Totalimmortal363 (Jan 10, 2008)

I got kinda freaked at first with my 55 about weight. Don't sweat it, your odds of breaking the tank with rocks are astronomical.

Queue pic of tank with lead shot in it.


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## SupeDM (Jan 26, 2009)

I just run the undergravel filter plates in all my tanks. It keeps the weight distrubuted and if a rock falls it doesnt have a chance of spiking against the bottom. also if the rocks are of irregular shapes it stops them from creating a single pressure point.


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## Dobbs92 (Dec 15, 2008)

Yeah, I may use egg crate for the same purpose. Actually the rocks I have are sandstone and after recently weighing the three largest they are not nearly as heavy as I first thought.


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## anafranil (Feb 8, 2009)

I guess you are all talking about the tank it self,how about the cabinet?Can a comerciall aquarium break under such sterss?


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## trigger (Sep 6, 2002)

People tend to forget rocks displace water. The actual weight of a submerged rock is far less than a rock on dry ground. If you put, say 100 pounds of rock in a tank with water, the tank will not weigh 100 pounds more. because of the rocks replace, say 70 punds of water that is pushed away out of the tank, so the actual weigth added is "only" 30 pounds. OK, these numbers are just grabbed out of thin air, because a lot depends on the density of the rock, but you get the picture i hope.


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## Dobbs92 (Dec 15, 2008)

Yes, Trigger, your point is well taken. Actually, I hadn't thought of it myself. And as I mentioned, the rocks I am using are Dakota Sandstone, which is not very dense. Hence it is relatively light. I'm certain that I won't have a problem. Thanks! As for the stand, I am relying on the manufacturer, Perfecto, as they manufacture both the tank and stand that I intend to purchase.


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## mnsignguy (Feb 4, 2009)

I have allot of lace rock and they are a very light rock, and very porous. Got mine at a LFS for $1 a pound. very cheap for a store bought rock. Shop around you'll find something.


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## Dobbs92 (Dec 15, 2008)

Actually the two pieces of sandstone that I have are quite large 30 inches or so long and complement each other well so they will form the basis of my rockwork. They are kind of like lacerock in that they are highly eroded with lots of little nooks and crannies. They sure won't be fun to clean. The funny thing is that they were on my property when I moved here being used as landscaping rocks. I've added a few more smaller sandstone rocks of a different type as well which I purchased at a local landscaping place for about 10 cents a lb. The LFS wants about $1.29 a lb. for lacerock, which I think is reasonable, so I may add a little to fill things out. I'm still planning things out so right now they are all being staged on my workbench for the time being.


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## Lostlilkidd (Jan 27, 2009)

mnsignguy said:


> I have allot of lace rock and they are a very light rock, and very porous. Got mine at a LFS for $1 a pound. very cheap for a store bought rock. Shop around you'll find something.


1 dollar a pound?
i cant find it for less than 3. Maybe i'll have more luck when spring its and the landscaping places open up.


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## Dobbs92 (Dec 15, 2008)

Uh-oh. Sounds like New York prices. We lived on Long Island all our lives before moving out here a few years back so I know where you're coming from.[/img][/code] I hope you find a better deal at the landscaping places. Good luck!


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## Lostlilkidd (Jan 27, 2009)

Yup, i was obsessed with the working on the rockscape starting two weeks back. But since the landscaping places are closed during winter... im going to have to wait for spring before i get rocks.

What a let down.


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## Dobbs92 (Dec 15, 2008)

Yeah, all dressed up and no place to go. I'm kind of surprised that no landscaping places are open yet. I can't remember from when we lived there but it's winter out here in Colorado and everyone is open. Strange.


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## Lostlilkidd (Jan 27, 2009)

Dobbs92 said:


> Yeah, all dressed up and no place to go. I'm kind of surprised that no landscaping places are open yet. I can't remember from when we lived there but it's winter out here in Colorado and everyone is open. Strange.


lol i dont kno.. maybe the recession?
haha


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## Curator (Feb 18, 2009)

average rock where I live at the LFS is around $5 a pound >.< which is why I just go to the beach and get my own...lol...now the local LFS occasionally buys rocks from ME for $2 a pound,lol...


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## Dobbs92 (Dec 15, 2008)

Yeah, I know what you mean. We are on the Colorado Plateau in canyon country so great rocks of all kinds are just here for the pickin'.


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