Say I want to make a large flat table of concrete and aragonite...

[Andru881]

Ok I thinking way in advance of tank I don't even have yet...

Well the plane is to make a large flat table rock out of concrete and aragonite...The size is going to be like 40"x 22" and its going to follow the loose shape of a cirlce. I want to have holes in it to let the water and fish pass through it. The problem is I want to have it as thin as possable while being able to stack around 60 pounds of live rock on it to make a wall in the back.

What could I use to brace the rock from the inside to keep it from breaking under the weight?

Where I work construction I know we brace concrete with steel bars inside, but I know thats the worce thing posable in a reef (I thought myself stupid when it first poped into my mind)

Would round acrylic rods work poured into the concrete?
I wasn't sure about how strong thouse things are?

Thanks for looking

[Nanook]

TTT

[CAT]

You could try fiberglass threads. They add this to the concrete mix when making planters for plants.

One warning though, I tried making cement rock a few years ago - it took forever to cure. You can't use it 'raw' because it drops the pH down to about 6.

hth,

[Adam]

Andru,

You could use a piece of 1/2" or 3/4" acrylic sheet. Drill or cut holes where you want them, plus a bunch of smaller ones for the concrete to "grab on to", and coat it with the mix.

HTH

Adam

[Frick-n-Frags]

I wonder if you could use some sheets of eggcrate as your "rebar", maybe stack two sheets off angle, tiewrap them together and chink out the holes(sidecutters cut eggcrate segments nicely, just watch for the "CHINK" sound when the little piece of plastic goes flying so it doesn't get you in the eye).

What would be cool is if you can mix a lot of plastic pieces-parts into your cement so it is much lighter than solid pure cement, then just sprinkle a nice layer of aragonite on top of the freshly poured cement, cover it until there is a nice dry layer. When it sets up (let sit for 2 days) turn it over and pour off the excess arag. It should look like just dry arag. Make balloons or latex glove balloons for making holes (they fill the holes for when you pour the cement, then pop them to remove them after the cement has cured.

You can make a nice sandcast setup with playsand in junior's green turtle sandbox that only the cat uses now :D. Put down a big plastic garbage bag and push in the shallow depression for putting your eggcrate mold into. Pour in a layer of arag and set in your acrylic or eggcrate etc and pour the cement in. This is a way to do a big, thin, wide piece like you are thinking of.

Cure the cement for at least 2 weeks. It puts out a really dangerous chemical called calcium hydroxide :D, but it is pretty much done after 2 weeks, totally done after a month. (I still think there is potential for casting certain sized pieces of cement and putting them in fresh as time release kalkwasser releasers :D)

I like tropicorum's setup. Cinder blocks with huge sheets of corrugated fiberglass with trays of aragonite on top of that. Nothing shmancy about that setup.

[Andru881]

I heard you have to cure it white vinagar for 12 hours and rinse them in fresh water before you use them...If there is any vinagar left hanging around on the rocks will that be enough to harm anything in the tank?