Do I need anything under a 5lb rock?

[PineSong]

I'm setting up my new tank and have a 5lb river stone I would like to put in. It's roughly oval and will be laying down longways, not arranged vertically. Am I correct that it's fine to just set it on top of the substrate once that's in--I don't need anything else to distribute the weight? I'll be using a couple inches of Caribsea Peace River as the substrate. 

[Nik_n]

If the substrate is deep enough it shouldn't be a problem. What type of substrate are you using, if it is a sand substrate you should be fine, and even with enough gravel. It really depends on the type of the tank and how the state it is in. I would but something below the substrate and the rock regardless. 

[BlueLineAquaticsSC]

5lbs is not to heavy for the glass. The problem is that rocks can have sharp protrusions and the weight can be pinpointed on the glass in a very small spot and cause it to fracture. River stone is usually pretty smooth and you shouldn't have any issues with it on top of your substrate. If you are concerned or if you wanted to go bigger, egg crate diffuser works great do distribute weight and can be hidden under the substrate. 

[Griznatch]

 As was mentioned, unless there's sharp pressure points directly against the glass, you can use some really big rock in your tank. I have personally had 10 to 15 pound rocks in my 55s and 75 gallon tanks. I did however, have plenty of sand/gravel as a buffer underneath.

[KittenFishMom]

I say a video where they put Styrofoam under the substrate before putting heavy rocks in to avoid pressure points. I asked on the forum about it. I will see if I can find it.

[PineSong]

Thanks all. I am just going to lay it on top of the substrate, then. It is an entirely smooth stone with no protusions. I was being cautious because it's by far the largest stone I've used in a tank, but I recognize it's not large compared to some of the rocks people put in big tanks. 

 

On 2/19/2022 at 2:11 PM, KittenFishMom said:

I say a video where they put Styrofoam under the substrate before putting heavy rocks in to avoid pressure points. I asked on the forum about it. I will see if I can find it.

That seems like something I've seen on aquascaping vids but I'm scared of styrofoam in a tank. I move plants around too much and poke my gravel with the tool I use to bury root tabs, I would not want to worry about anything I could tear up being under my substrate.

[Scott Stevenson]

oh boy, i have multiple Seiryu rocks, some surely 5lbs or more sitting on a bare bottom, old 40g tank right now. I plan on putting gravel in within the next couple months, but now im worried.

Edited February 20, 2022 by Scott Stevenson

[Torrey]

On 2/19/2022 at 12:21 PM, PineSong said:

Thanks all. I am just going to lay it on top of the substrate, then. It is an entirely smooth stone with no protusions. I was being cautious because it's by far the largest stone I've used in a tank, but I recognize it's not large compared to some of the rocks people put in big tanks. 

 

That seems like something I've seen on aquascaping vids but I'm scared of styrofoam in a tank. I move plants around too much and poke my gravel with the tool I use to bury root tabs, I would not want to worry about anything I could tear up being under my substrate.

I use the same egg crate light diffuser to distribute weight more evenly across the tank. 5 lb rocks are generally not an issue. It's the large 12+ lb rocks that are resting on a few pointed spots that gets me nervous...