Adding Large Rocks To A Tank

[Ryefish]

I bought two large pieces of slate rock to add to my tank, and another bag of play sand - there will be overall about 20kg's of sand and two huge rocks (id say about another 10kgs). My mother is freaking out, positive that the weight is going to smash my tank, or that the weight is going to be too much for the cabinet.

I've seen members with tanks that have had huge rocks in there, and huge pieces of wood and loads of sand too

Is all this rock and sand actually going to make any difference to my tank? There isnt a brace bar attached to the tank itself, but there is a metal brace bar on the hood of the tank under the lights


ETA: I had no idea where to post this, so sorry if its in the wrong place

 

[jameshunter63]

should be fine mate. Just make sure they cant fall and you dont hit the glass when you put them in. A tank is built to hold a massive weight of water and so decorations are fine. And if its a proper cabinet for the tank it will easily hold it. really do not worry! will be absolutely fine.
james

 

[OldMan47]

As long as you have something to spread the weight of the large rocks over a large area, the weight should not be a problem in a typical tank. I have some very heavy rocks in my 120 gallon tank but I have them sitting on a bed of gravel several inches thick. That bed of gravel serves to prevent the rocks concentrating any weight in a small area. You could think of it as the gravel providing a cushion. Simple weight of rocks and gravel is often as much as twice the weight of a similar amount of water so it can eventually become too much if there is an inadequate safety margin designed into your tank. You can probably expect your 30 kilos of gravel and rock to displace 15 or so litres of water so you have only really added about 15 Kg to the tank and its stand.

 

[Ryefish]

Thanks for the replies!
I forgot about the displacement and weight of water. I am keeping the current sand in there, placeing rocks on top, and then banking sand up, so i think the overall weight should be equal around the tank. the rocks arent going against the tank sides, just slightly off-centre. i believe it will all work fine (... )

 

[Ryefish]

Added the rocks to the tank and.. GUESS WHAT!!! the tank is still in one piece

 

[SDWalters]

Haha, Your mother can now rest easy!!

I had a major disaster with rocks on my previous 80gal!!!! During a rescape a LARGE rock slipped out my hands and cracked the base of my tank and the 80gallons of water began seeping out......

So me and my dad frantically tried to slow the water flow, while my mum and brother girlfriend shot off to the local diy store to get some large plastic bins, my girlfriend began catching fish and my brother.......... stood and laughed at me lol.


Lesson learnt! be super careful when placing and moving rocks because well glass cracks!


All ok now, all fish unharmed and rehomed in a new 100gal so happy ending (This was around 8 months ago but still fresh in my memory!)

 

[xxBarneyxx]

Yeah nothing to worry about. In the marine side you often have a lot of rock in the tank (I currently have about 50KG in my 100g).

I would however disagree with putting rock on top of substrate. Depending on your livestock substrate can get moved around quite a bit which makes the rockwork unstable and can cause it to fall.

I (and most people with marine tanks) put the rock directly on the glass then add the substrate around it. If you are worried about causing pressure spots then the best bet is to put down a layer of eggcrate where the rock will be and then put down the rock and then the substrate. This spreads the weight over the glass and makes sure the rock wont slip or fall.

 

[OldMan47]

Nice tip Barney. I only keep mostly small tropicals and they tend to leave the gravel where I put it. I suppose that large cichlids could definitely move things around.

 

[Modelworks]

. If you are worried about causing pressure spots then the best bet is to put down a layer of eggcrate where the rock will be and then put down the rock and then the substrate. This spreads the weight over the glass and makes sure the rock wont slip or fall.

I like to look over the rocks I intend to use for any trouble spots and use a sander, dremel tool or hammer to flatten any pointy spots. Both for the glass and to prevent any fish from getting cut.

 

[anon02]

You can buy a plastic mesh grille that`s meant for covering pond filter, sunk just below your substrate it wouldn`t even be visible and it would be ciclid proof !!!