How much rock?

[tfoster]

Hey All,

I'm concerned that i need to add more rocks to my 4 footer, but not sure if the glass will take to added weight.

I have two small piles positioned at each end of the tank. I'm using colac honeycomb rock which can be somewhat heavy. Sometimes the area taken is of greater weight than the same amount of water.

The tank is a 4' x 18 x 18 using 6mm and i am using river sand as my substrate.

I have positioned the rocks on a layer of sand to prevent any damage to the glass, I hope this will prevent any scratches becoming cracks.

So how much is too much?

Cheers

Tim.

[r.d.m]

what you need to watch out for is that no fish can burrow under the rock bringing the whole lot down,the best solution is to cover the tank bottom with eggcrate(or similar) then put in the rocks(try not to lean them on the glass)then fill up the gaps with sand or gravel. most tanks will take a fair amount of rockwork but be aware its easy for a 250l tank to become a 150l tank if you over do it !

[davez104]

Not sure what you mean by "Sometimes the area taken is greater than the same amount of water. " but I think the main concern is to avoid pressure points on the glass. You have tried to do this by using sand but be aware that fish can, and usually will, move sand very quickly and easily. You could try putting something like eggcrate or something similar under the rocks to spread the weight a bit.

Hope that helps.

[darkmuncan]

um,

dont use eggcrate, it will turn to mush

use thin pieces of styrofoam underneath the rock pieces. This spreads the weight of the rocks out over a larger area and avoids too much point pressure being placed on the glass on the bottom.

you just need to make sure you have adequate substrate/rocks on the styrofoam to hold it down and make sure it doesnt float back up

[davez104]

Eggcrate: plastic grid stuff used in shopping centre lights etc etc.

Shouldn't turn to mush I don't think.

[WAZ]

I think Darkmuncan is referring to the mush (detritis) build up, over time in the square grids of the egg crate. I agree with this too.

I would not put polystyrene under the rocks either, it will not spread the weight as stated previously. Also your fish will pick at it and you will have balls of polystyrene floating all over you water surface, also the polystyrene will breakdown over time, being submerged.

If you feel you have to put something under the rocks, I would suggest running beads of silicone over the area where you want the rocks, ie in a zig-zag manner, before you put any water in of course. Let the silicone cure for 24 hours.

Do not put rocks onto substrate or sand as others have said.

The critical factor is whether the glass bottom is fully supported on polystyrene and under that plywood or equal.

If this is the case I would place the rocks directly onto the glass.

I have 200 kilos of Coober Pedy rock sitting directly onto the 10mm glass bottom of my show tank - been like that 2 years now and no movement whatsoever. Just make sure when building the rocks up that the bottom rocks are secure and not rocky ( ).

WAZ.

[anchar]

I agree with everything WAZ has said. If you take a lot of care when stacking the rocks and be sure that they can't fall or be undermined through digging, you will be fine. I have about 80kg of rock in a 4' x 18" x 18" Obviously it leaves very little swimming space...but that's the way Tropheus spp. like it. Depending on the type of fish you plan to keep, rock can be put together to form walls, piles, caves or small "landmarks". Mbuna prefer a lot of rock whereas "haps" need open water swimming space.

Andrea

[teflon]

Don't forget the fact that you can silicone the rocks together

[Neil]

I have been siliconing holley rocks together and just before the silicone skins I've been licking my finger and covering it with a similar coloured substrate as the rock then poking the substrate into the silicone to cover the joint . This way you don't get to see the obvious blobs of silicone bulging out of joints and also works great for silicone type feet to save direct contact with the glass. Just remember to place them outside to cure in the sun .This way I don't get to be to impatient, a week is better than 2days I reckon.

Neil

[youngy_11]

All you need to do is place or either silicon styrafoam to the bottom of the rocks to even out the weight. And don't put to many rocks in the tank because it is a waste of space and your tank won't hold as much water as i would of before.

[barramundi]

Hey Tfoster. I agree with Waz & Merjo. i thought I'd share something I've done though, in case it can help too. I have a few rock structures that I have built onto a piece of 6mm glass. I've siliconed them down onto the glass sheet & the sheet fits into the bottom of the aquarium. That way the rocks are siliconed down (but not permanently stuck to my tank), the weight is spread across the piece of glass not causing pressure points on the tankbase itself, & it also prevents any risk of rockfall. HTH.

[tfoster]

I have a few rock structures that I have built onto a piece of 6mm glass. I've siliconed them down onto the glass sheet & the sheet fits into the bottom of the aquarium. That way the rocks are siliconed down (but not permanently stuck to my tank), the weight is spread across the piece of glass not causing pressure points on the tankbase itself, & it also prevents any risk of rockfall. HTH.

←

Great idea Barramundi, I will do that next time.

I have alreay put my rocks in and do not seem to have any problems.

Next time I decide to change the design i will follow this simple but brillant idea.

Cheers

Tim.