How much weight can bear on the tank bottom?

[AndreaW]

Remember this driftwood setup? 

I was sanding the pieces to fit them together and I began wondering if it would weigh too much. Under the big rock on the right, I will have 15 lbs. pressure. It's spread out over 6" x 3" flat bottom that will rest on gravel, on top of an UGF grid. The other end (low end, at the middle) will have 4.5 lbs. and I plan on resting it on a flat river rock to distribute and support it.

Should I be worried about the 15 lbs? The rock alone is over 7 lbs.

Edited March 15, 2022 by AndreaW

[StevesFishTanks]

 

What size tank and how thick is the glass?

I think with enough of a footprint to spread out the load you will be fine. Especially if its on top of the UGF. 

In my heavy hardscape cichlid tanks many years ago I would buy egg crate light diffuser and put it across the bottom of the entire tank to spread out any point load caused by rock structures.

[AndreaW]

On 3/14/2022 at 8:46 PM, StevesFishTanks said:

 

What size tank and how thick is the glass?

It's a 46G bowfront tank by All-Glass (bought by Aqueon). I don't know the thickness of the glass, but the bottom is tempered and there is a support bar front to back in the middle of the tank. The white paper in the pic above is a template of the tank and shows approx. where the rock will be placed in the tank. 

[Brandon p]

Most Tanks in the US have stronger glass. That tank I’m almost sure that that company uses Tempered glass with is 4-5 times stronger than annealed and laminated glass.           Check out

Intuitive Marine 

Auga Gadget Leveling adhesive rubber mat

 

this with help strength the tank as well

There is all this heavy coral limestone rock plus 3.5 inches of crushed coral and blue rocks my ex wife wanted. It’s be there for 10 yeas and had more rock on the right size of the picture and I will put some more back if I find the right pieces. I think you will be fine

Edited March 15, 2022 by Brandon p

[Patrick_G]

I agree, the bottoms are pretty strong. I’ve piled a lot of rock in various tanks with no problems. 

[lefty o]

the only time weight is really an issue is if it is directed onto a tiny area, such as a sharp corner on a rock. i mean that tank bottom is going to hold close to 400# of water.

[AndreaW]

Thanks for the reassurance @StevesFishTanks @Brandon p @Patrick_G & @lefty o

Specifications do say the weight of the tank is 550 pounds when filled. That's a lot of pressure overall on the bottom glass, so I suppose 15 lbs. shouldn't be a big deal if it's distributed. I'm just trying to make sure it has a very stable base so it can't possibly tip and hit the back wall.  I've been cutting and sanding grooves into the bottom of the wood to match the rock and still plan on adhering it well.

My son has a tendency to stick his hands in the tank and even though I've told him he's not allowed to move anything in the tank I never know what his impulsive ADHD brain will allow him to remember. 

[Andy's Fish Den]

You'll be fine. People pile large amounts of rock in tanks all the time, especially for African cichlid tanks. 

[Patrick_G]

On 3/15/2022 at 3:32 AM, Andy's Fish Den said:

You'll be fine. People pile large amounts of rock in tanks all the time, especially for African cichlid tanks. 

That’s what I was thinking. When I did cichlids I had a huge pile of limestone/coral for my melanochromis.