How would a tank made of stone instead of glass. Have 3 sides stone and one glass. You could even carve your own Backdrop. Only set-back is how fragile it'll be and weight. You just need to silcone peices together and add the plastic rim to the bottom.

I have a slate bottom tank which is the way they used to be made. They are quite a bit heavier but it can be done with stone.

Might try this one day then.

Fairly expensive compared to glass as well, but it can be done.

Keeper

I would use fiberglass on the insides. I have this wierd thing were I do not want the smallest possibility of stuff leaching into my water.

My question would be, (I don't know if it will make sense, so forgive me now) wouldn't the stone absorb alot of water. I mean it's one thing for it to be setting in water but when only one side is in the water wouldn't you constantly be adding water to the tank? And wouldn't it eventually leak? Wouldn't you have to use some sort of sealer on the stone?
Maybe i'm just thinking too much!!

Naw it is like porcelin or ceramic or clay. WOuld non porous so It wouldnt be an issue. Kind of like planters that you would get to plant plants in. Now I prob wouldnt trust anthing over 30g but that is me.

I was thinking cement.

Told ya I was thinking too much!!!

Making cement completely waterproof is a bitch and a half though. You could make fiberglass look enough like stone and not have to worry about the weight or the potential for cracking.

I'm not sure that I understand the point of attempting this but...O.K. I'll play.
Are you thinking stone as is cut like tile, (slate or granite for example)?
If so yo can purchase stone tile in either variety up to 18" square or better. I've built glass tanks with just 1/4" up to 17" water depth so I guess the stone would be as strong, but I'm not sure since glass actually does have some elasticity to it. In other words it will bend before it breaks if too much water pressure is placed behind it. I don't see stone bending, just failing catastrophically. It's got fantastic compressive strength (when laid flat on a floor or wall), but these would not be the same forces when used for a tank.

Of course I guess you could take great thick counter top slabs and silicone them together. Just make sure that you build it where you'd like it to stay for....maybe ever.

Here's another idea in the weight is no object vein.

There's a product available called self consolidating concrete that works great for concrete counter tops and yard statuary. It has a polymer added to it that causes all of the aggregate in the mix to act like similarly charged magnets so they tend to spread themselves very evenly throughout the mix, thereby increasing the strength when cured tremendously (6,500 psi for example). The stuff used for counter tops and statuary molding has a much smaller sized aggregate in it than say what you would typically see in a foundation or building slab, in order to allow a tighter, finer finish.

Two inch thickness should be adequate and would be thick enough to contain loops of 3/8"-1/2" PEX (cross linked vinyl tubing used instead of copper pipe in home building today). The PEX tubing would carry hot water from whatever source you choose (remote heated sump, domestic water heater, solar panel, et al). The density of the concrete would function as a giant thermal battery and temperature buffer. Once warmed, which would doubtless take a while, it would release its heat very slowly, so you wouldn't need a lot to keep it warm once it was up to temperature...as long as it was insulated.

Which brings me to the point of using concrete in the first place. It is incredibly easy to form. Any shape that you can dream of can be constructed of concrete. There's an architect who builds giant concrete domes by forming the structures over stadium sized balloons. In building construction there have been insulated concrete forms in use for quite some time (ICF's) and the same principle could be applied to building tanks. With the bottom and three sides insulated with rigid foam, and a glass or acrylic lid insulated with the same, the tanks heat loss would be minimal...except for through the front. Since regular plate glass has almost no resistance to thermal energy transfer (low "R" value) the next best thing (other than high tech composite glass and coatings) would be cell cast acrylic, since it is both optically desirable as well as being a much better insulator.

With LED lights built into the lid and an insulated front cover that can be removed and applied gradually but simply (maybe a hinge and some pulleys) - to keep from freaking the fish out - the whole affair could be made extremely energy efficient. Think of how quickly a cold glass of beer gets warm compared to how long an 1/8" thick Styrofoam cup with a 30 mil. plastic lid stays scalding hot. The insulation would only be applied to the outside and a removable wooden form with an acrylic face would shape the inside. Concrete doesn't stick to the acrylic so stripping the interior form later is simplified and the form would be reusable.

The self consolidating concrete can be purchased in bags and hand mixed in a pan or by the truck load as ready-mix. Penetrations for specialty lighting and plumbing are all easily cast into the form anywhere that you want them because the strength of the concrete is ridiculous. Epoxy, acrylic or rubberized paints are available that can be applied to the interior assuring water tightness and providing limitless color choices. I haven't checked it for fish safe use but there's a product called Roll Stone and Roll Rock that is an acrylic paint that can be applied as a paint or textured to work like stucco. It might provide enough meat and adhesion to allow mixing some natural stone into the finish. For that matter you could set the stone into the interior face of the form and pour the concrete in behind it, or cast a mold.

To make the mold you would build a natural layered stone back ground with maybe a big stump or root section poking out of it. There are latex and urethane rubbers that can be painted or poured over the real background. After the mold dries you have to build or pour a back up for the rubber mold and then integrate that into your interior tank form. Once the concrete has cured something like the acrylic Roll Stone could be mixed up in several different colors and applied to create whatever level of realism that you desire. The mold would be pretty expensive and probably not worth the squeeze unless you were going to build multiple tanks. There's already a company using this process to manufacture 3-D structural foam back grounds that are absolutely gorgeous and totally real looking...and stupid expensive (something like $200 for a 18" X 48").

Then, when you're all done, go chop a huge hole in your wall so that the forklift has a way to get in and pick the bugger up for ya...

It may not be practical or desirable for most uses but it'll make ya think.

Cool ideas Worknfool! The only problem with concrete is it is great in compression but not in tension, so some steel reinforcing would need to be added. On a small scale tank some wire mesh could be used to keep tension cracks from forming and on a larger scale a grid of rebar would be required.

Concrete tanks are actually done quite often (they are called swimming pools) and the products often times used are called gunite & shotcrete. I'm actually working ona local YMCA building and the process is pretty cool to watch.

You are correct that you can do just about any shape you would like as long as someone can form it and place the reinforcing to that shape. There are several Architects that have used free-form concrete in their buildings but one of the early pioneers is Le Corbusier. Try googling his chapel of Notre Dame du Haut in Ronchamp. It's pretty awesome and hard to believe it was done 56 years ago.

Here's a pic...