Hardscape additions: REALLY HEAVY rocks

  • We are currently upgrading MFK. thanks! -neo
By the way, to spread the weight, in the picture, you'll see a combo of materials, but I think I'll only need 2. It's difficult for me to find eggcrate light diffuser here, so I used what they call kennel board which looks more sturdy to me. And I used chopping board as another further step taken to ensure weight distribution is really effected. My choice of these materials are simply it's easier to find then what the professionals recommend, and chopping boards should be food grade, which means it should be extremely safe for aquarium use. I might add a bit of high density styrofoam which I have purchased, but the function is more for preventing sand from dropping into the empty kennel board space then for anything else. And of course, I'll cover them with thick sand substrate. There's also a piece of hardwood you'll notice on the right which I hope can also help soften water and it's my personal opinion that it looks like a sunken tree....lol.

Hope that helps, my friend.View attachment 1411833

A hundred pound rock resting against the bottom of the tank at 3 sharp points providing 1 square inch of total contact area is exerting 100 psi on the tank bottom at those 3 contact points. Spreading that weight over a 10" x 10" area (100 square inches) results in 1psi being exerted on the tank bottom by the same 100lb rock.

3 sharp points on a jagged rock are likely to make less than a total of 1/16 of a square inch of contact area. In this case there will be over 1600psi exerted at those 3 points.

I like your plan... it is what I would do!

Remember the relative weigh of a rock will be significantly higher in a dry tank than a filled tank... depending on the rocks density/buoyancy. Keep this in mind when placing your rocks.
 
Last edited:
My brainstorm during lunch. Overhead gantry made from 3/4in black pipe. I can get a 6ft pipe, elbows, 2in nipple, and flanges. Mount to ceiling joists and use a 1/8in steel cable and pullies that I already have. I will need to make or obtain a sling that will support the rock but this should work. I will position the rock with the aquarium empty. The rocks I'm considering do have flat spots they could rest on.

It should probably work but isn't the approach I would take. (Iron pipe attached to the ceiling securely DOES sound line a good plan!) A simple 2x4 "A" frame or "Y" frame would do the job just as well if not better and would be cheaper and most likely easier to work with.


Here is a picture of me unloading my 2500 lb lathe by myself with the 2x4 "Y" frame gantry I built:
20180204_183841.jpg

I used tippled up laminated 2 x 4's for the uprights and three 2 x 12" for the header. For a 200 lb rock there should be no need for using multiple 2 x 4's laminated together for the uprights. A single 2 x 4 should be fine for the header (and uprights) but you could use a 2 x 6 if you wanted some extra insurance. Make sure to use sufficient diagonal braces to prevent the gantry from tipping over. Use screws, not nails! Wood is great stuff if you design to its strengths!


P.S. rope should be find for a 200 lb rock. Steel cable sounds like overkill and harder to work with... but would definitely get the job done. Use a compound pulley setup (block and tackle) to make the rock easier to lift and set down easily.
 
Last edited:
  • Like
Reactions: fishguy1978
Remember the relative weigh of a rock will be significantly higher in a dry tank than a filled tank... depending on the rocks density/buoyancy. Keep this in mind when placing your rocks.
Yup. My biggest rock are granite. Measured at 47kg (approx 100lbs). I'll be using multiple woven polyethylene bags rated good for 25kg, those used to pack many items like salt etc which I got for free instead of sling/cables. I'd think those 1000kg tote bags is definitely best option and I have plenty in my factory, but being a chemical factory, bad idea. I'm going to stick a thick layer of styrofoam (1.5 inch) on both sides of the glass where I'm doing the work. I'm planning to also put sand bags on where the passover of rocks take place. I know it's no guarantee, but I am hoping every little helps. I don't have the confidence in the structure above my tank to use a pulley... but if done right, and my mates can safely lift the rock to the resting platform close to the height of my tank, in theory, as long as I manage to rest it gently on the sandbags or chopping board, I should be safe.
 
  • Like
Reactions: Oughtsix
P.S. A 12" x 12" granite tile is only a couple bucks at Lowes. It is very flat and very ridgid... it would probably make a very good platform for a heavy rock. I would probably place it upside down so the flattest (shiny) side is against the bottom of the tank.
 
Last edited:
P.S. A 12" x 12" granite tile is only a couple bucks at Lowes. It is very flat and very ridgid... it would probably make a very good platform for a heavy rock. I would probably place it upside down so the flattest (shiny) side is against the bottom of the tank.

I have a couple left over from the previous owner installing granite tile countertops, fugly.
Has anyone used the Smartpond Pond Foam? I'm thinking that a foam base to the rock I want to use will promote it's stability.
 
Here is the thread I was referring to. The video is what I was thinking about.

Look at some of the tanks in this thread.
 
Here is the thread I was referring to. The video is what I was thinking about.

Look at some of the tanks in this thread.

Thanks, the network I'm on for work blocks youtube so I will check out the videos at home.
 
  • Like
Reactions: Zanzag
So, I put 21.75 inches of water in the 220 and was within 1/16 or better in 4 places. I call leveled and filled half way.
Rock is where I wanted but I could not get it stable in the verticals so opted for horizontal.
599DDA01-F057-4108-8B15-EBB4C09EBB18.jpeg9702A14A-BC44-4CF0-98CE-08881D8AFC2A.jpeg7DE19301-A356-4B65-8551-A61E70523531.jpeg
 
How did you manage to get a rock so heavy past the tank top to rest gently on the tank? I'd like to try your method since it worked.

If the rock was any lighter, I'd be worried with the rear edge being quite close to the glass panel. It may be more work to clean that part of sand though, but your tank, you're the best judge. What fishes do you plan to have, just out of curiosity, if you don't mind.
 
How did you manage to get a rock so heavy past the tank top to rest gently on the tank? I'd like to try your method since it worked.

If the rock was any lighter, I'd be worried with the rear edge being quite close to the glass panel. It may be more work to clean that part of sand though, but your tank, you're the best judge. What fishes do you plan to have, just out of curiosity, if you don't mind.

So, I ended up placing the rock in a milk crate and getting my 16yr old son and my wife to help me lift it into the tank. I placed a piece of 24in long 1x12 on the center brace to add some extra safety. The rock rests on a piece of 3/8ish acrylic and then is shimmed to keep it from rocking. Ideally, the rock would have been vertical which is what I really wanted as the tank is 30in deep.
I do have a really cool chin up bar mounted to the ceiling though, :ROFL:
As for fish I will be moving my 10 SD from the 90g and the 2 flagtail porthole cats as well. I would also like a school of cory cats. I have 5 bronze cory I could move.
 
MonsterFishKeepers.com