# piling rocks against glass



## zcfish (Jan 31, 2009)

what are the potential problems of piling rocks against the glass? maybe some cleaning issues? it would be quite difficult to pile rocks high and keep them stable without touching the glass. also you'd get a 3d background this way as well. obviously one need to be careful when placing the rocks. this is a 125g 6ft long.


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## ridley25 (Jan 5, 2008)

I do this on a much smaller scale: 38 gallon, 36" long. I place the odd rock against the glass so I can build high - crud does start to build up against the glass - but since it's a small number of rocks, I rearrange my pile every three weeks or so during cleanings. One of the few advantages of a small tank.


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## Mcdaphnia (Dec 16, 2003)

Collapsing rock walls can crush fish or scratch the tank glass. Cracking the bottom from the weight, trapping fish or having fish die where you can't retrieve them is another hazard. The build up of detritus can probably be handled by using powerheads as one uses a leaf blower to clean up a yard in the fall. The powerhead(s) can be left in position and moved periodically. Or you can use the flow generators common in reef and frag tanks to keep detritus from settling anywhere but inside a filter. If the rockwork is to be extensive, I'd use waterfall foam to protect the back and bottom, stabilize the rocks and fill the deepest cavities that are likely to pose a mantenance problem.


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## CICHnes (Jan 30, 2009)

Use egg crate on the bottom of the tank to evenly disperse the weight on the bottom and if you can use the same egg crate on the back if you aren't going to build a DIY background. Just cover the egg crate with rocks so it can't be seen. If the unfortunate event that it does fall, the bottom of the tank won't be damaged from it.


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## Mcdaphnia (Dec 16, 2003)

CICHnes said:


> Use egg crate on the bottom of the tank to evenly disperse the weight on the bottom and if you can use the same egg crate on the back if you aren't going to build a DIY background. Just cover the egg crate with rocks so it can't be seen. If the unfortunate event that it does fall, the bottom of the tank won't be damaged from it.


 Unfortunately egg crate telegraphs any rock impact directly to the glass, and it may concentrate the impact at a point on the plastic grid. Like with a car bumper, you need something compressible that will absorb, not transfer, impact.


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## CICHnes (Jan 30, 2009)

Are you sure you're on the right forum, last time I checked egg crate (light diffuser) does not do that. I haven't had that problem yet, had a couple slides already, nothing major and nothing happened, if it does impact the grid it spreads it out, rather than concentrating it on a single point of impact therefore protecting the glass, the tempered glass on the bottom can take a force spread out over an area rather than a single concentrated point. I guess I'm not the only one who thought of this.

http://www.cichlid-forum.com/phpBB/view ... p?t=186643

Not sure if this one is ok, but this should also validate my point pretty clearly, its on another forum.

http://www.cichlidforums.com/showthread ... t=eggcrate
http://www.cichlidforums.com/showthread ... t=eggcrate


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## iceblue (Apr 27, 2004)

The flexible nature of the light diffuser is not designed to spread out the force of an impact. Their have been far more exhaustive threads written on the subject in just this Forum then the ad hoc few that have been presented. A bed of sand will do a much better job of distributing the weight of a falling rock and as was pointed out in one of the posted threads, rocks weigh far less when displacing water in the tank.

If it makes you feel better having egg-crate in your tank then by all means use it, but their are plenty of tanks out their that don't and they handle the weight of the rocks just fine.

When stacking any rock you have to use gravity as a guide to make a stable structure. If your fish are big brutes stacking rocks is probably not a good idea. If your going to stack against the side of the tank then Mcdaphnia has given couple of very good ideas to prevent scratching.

Another alternative is to get a thin piece of black plastic and silicone it to the sides of the tank to protect the glass.


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## BillD (May 17, 2005)

Inspite of the plethora of egg crate supporters here and elsewhere, I have to agree with Mcdaphnia on this. Whenever you use anything hard and rigid, you risk a pointload, especially if using gravel. Less of a concern with fine sand, although, as mentioned you shouldn't need it if using fine sand.


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## Stickzula (Sep 14, 2007)

The weight distribution that egg crate either does or does not provide seems to be a personal judgment call. There are theorys about it both ways. The only benefit that I have found to using it is that you can tie driftwood and ugj's to it. With the weight of the rocks on top of it, the driftwood and ugj's stay put. If it gives you peace of mind, then that is a bonus. As for leaing rocks on the glass, I have done it without any problems, less a few scratches. So if scratches bother you, and they should, then use some protection as outlined above. :thumb:


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## mthigpen_02 (Dec 29, 2008)

In my 55 I had stacked rocks all the way to the top without touching the sides. I have since taken it down to about 3/4 high but not because of stability reasons but because it blocked all the light. Sometimes it takes a long time to get it right but it can be done. After each layer of rock I shake every rock if any move I try to move it so they won't move or try another rock in that spot. Once I get them piled like I like it I purposely bump into the pile with the cleaning brush just to make sure nothing moves. If any rock moves I usually take it all down and start over depending where the moving rock is located. So it can be done without touching the glass and leaving enough room to scrub the glass.


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