The Ultimate DIY Rocks!

[airinhere]

Insanereefer, Awesome link. I guess the stuff I am refering to is the effloresence. Just salt precipate. And I was all woried about its impact in my tanks....

Doahh, if you want to get the white cement, try looking in the phone book for: concrete-ready mixed. Its going to cost you about double what you pay for the grey stuff, but I really prefer the pieces I made with the white.

 

[Doahh]

I like the look of the gray IMO...

 

[Tahlequah]

<a href=showthread.php?s=&postid=9902537#post9902537 target=_blank>Originally posted</a> by Doahh

45 gallon rubbermaid pond
90 lbs protland cement
100 lbs solar salt from sams club
100 lbs oyster shells...

mix
3parts Oyster shell, 1 part Portland, 1 part Solar Salt

I think you might want to double up on your solar salt, the more porous and permeable the better.

 

[Doahh]

at 10 bucks for 100 lbs that shouldn't be too hard...
wait so now I'm mixing 3 parts OS 1 part cement 2 parts salt?

 

[Insane Reefer]

Actually there is NO evidence that more porous is better - no laboratory testing has ever been done that has been published.
IMO, super porous rock just means you will be having to vacuum/blow those rocks more often as detritus will have all sorts of "dead space" to get trapped in.

I use 1 part salt in my rock and it is still more porous than real live rock - anything more than 1 part salt and I personally have trouble with the rock holding together.

Doahh, your first plan of 1:3:1 will work just fine - you don't want to go over the 3-4 parts "other" to 1 part cement or you may encounter trouble.

 

[goldmaniac]

I've found that the 1:2 ratio is very strong

two parts salt to one part everything else

one part cement/sand/substrate to two parts salt can hold up to me (180 lbs) standing on it. Including 16 inch "bridges". That's after a 48 hour soak in running water to remove majority of rock salt.

I made one batch with old refugium sand, and one batch with kitty-litter sized substrate. Both very strong.

I haven't used it in the tank, yet, though.

 

[GuySmilie]

<a href=showthread.php?s=&postid=9907544#post9907544 target=_blank>Originally posted</a> by Insane Reefer
Actually there is NO evidence that more porous is better - no laboratory testing has ever been done that has been published.
IMO, super porous rock just means you will be having to vacuum/blow those rocks more often as detritus will have all sorts of "dead space" to get trapped in.

I use 1 part salt in my rock and it is still more porous than real live rock - anything more than 1 part salt and I personally have trouble with the rock holding together.

Better as in what?
I think it's been researched to death that the more porous the media surface, the more susceptible it is to the growth of bacteria. Whether it's the type of bacteria a person desires, that is another question. But I believe that is what folks are referring to when they say "more porosity is better."

And I agree with you that the more porous the media, the more detritus it will entrap. Thus, more maintenance could be involved.

I also prefer a 1:1:1 salt-Portland-aggregate ratio. Any more salt than that has produced rock of less strength for me as well. Not that the rock must be strong, but it is more delicate to handle, I find, when more salt is added.

 

[Insane Reefer]

When you add sand into the equation, rock becomes ever so much stronger, but Doahh is planning just OS and Salt - IME, this will produce a brittler rock, especially if 2 parts salt is added.

Doahh, when you are at the feedstore getting the Crushed Oyster shell, ask and see if they have "Limestone Grit for Feed Mixing" - if they do, it will be cheep - like $3-5 for 50#. Make sure it is limestone and not granite though. This stuff is sort of like beach sand, but a bit more grey. It is made from ground up old seabeds and has a high calcium content. I am using this for sand - both to cast in and to mix in and it is great stuff.
This will make you very hard rock. Try a mix of 1 cement, 1.5 OS, 1 Sand and 1.5-2 salt. Personally though, I would only use 1 salt.

 

[JCOLE]

I was thinking since i live about 30 minutes from the ocean, if i made these rocks and then put them in the ocean for about a month this would put a jumpstart on things?

 

[impur]

My 1:1:1 ratio rocks are incredibly heavy. I made a flat piece that will be part of a structure, its about 14"L X 8"W X 3" thick and it probably weighs 50lbs. I'm not going to use it, its just too heavy IMO. I am going to try making another with more salt.

 

[Doahh]

Wait so how do you "Mold" your rocks?
I was just thinking you plop down some cement... or is there more to it?
So I should do a 1-1.5-1-1
Portland Cement
OS
Sand
Salt

 

[Insane Reefer]

<a href=showthread.php?s=&postid=9909912#post9909912 target=_blank>Originally posted</a> by H2oH2o
...if i made these rocks and then put them in the ocean for about a month this would put a jumpstart on things?

This is a perfectly acceptable scenerio. You will have a quicker (easier & cheaper too) kure and get bacteria (and probably other things) to boot.
The biggest hurdle is keeping the rock safe from theft and the ocean itself - the ocean can really move things around, so try to find a place were it won't just get swept out to sea with the first good storm.

 

[Insane Reefer]

Doahh, did you ever play in a sandbox as a kid? Same idea. Use pretty much anything you want; sand, salt, soil, unscented kitty litter, whatever you want.
I personally like sand. You can wet it down and make some really cool shapes by scooping out hollows and building up hills. Make little "balls" of wet sand and slop cement over it for caves or voids. Salt works too (don't wet it), but I can get much nicer, more natural shapes with the sand.

 

[drauka99]

<a href=showthread.php?s=&postid=9910589#post9910589 target=_blank>Originally posted</a> by Insane Reefer
This is a perfectly acceptable scenerio. You will have a quicker (easier & cheaper too) kure and get bacteria (and probably other things) to boot.
The biggest hurdle is keeping the rock safe from theft and the ocean itself - the ocean can really move things around, so try to find a place were it won't just get swept out to sea with the first good storm.

Crab box tied off to th end of a frinds dock would work best

 

[Doahh]

Can someone please update my list for my 90g tank... the sand kinda confused me...

 

[Rhodophyta]

<a href=showthread.php?s=&postid=9909912#post9909912 target=_blank>Originally posted</a> by H2oH2o
I was thinking since i live about 30 minutes from the ocean, if i made these rocks and then put them in the ocean for about a month this would put a jumpstart on things?

This would be a bad idea in Florida or other southernly states. You could be charged with dumping or other charges if caught putting them in the water, and being caught removing them would be worse.

 

[Doahh]

*Totally Confused...*
Do I mix the salt into the rock or use it as a mold along with the oyster shell?
Or do I add the salt OS and sand and cement into it and use sand as a mold

 

[Rhodophyta]

<a href=showthread.php?s=&postid=9918413#post9918413 target=_blank>Originally posted</a> by Doahh
*Totally Confused...*
Do I mix the salt into the rock or use it as a mold along with the oyster shell?
Or do I add the salt OS and sand and cement into it and use sand as a mold

The short answer is, "Yes." but it really depends on whose technique you are trying, since any of the scenarios you paint have been used by someone and probably posted somewhere on this or a predecessor thread. If you want a lot of detail and control of your product, you would use sand as the mold. For exceptional detail, you'd mix oat flour and molasses into the sand for the mold so that it has a clay like consistency. Then any shape you press into it would transfer to your rock, in reverse of course. Because of the flour and molasses, the sand would not adhere to the rock and would fall off as it cures, leaving fine detail. If you like creative and random, you'd use coarse salt as the mold and end up with a very textured/spongy looking product after the salt washes away.

As to what to add to the rock itself, sand and calcareous gravel add strength. The portland cement is the active ingredient, and salt is just a cheap way to create voids in the rock that can be dissolved out once the rock has cured.

 

[GuySmilie]

Cactus Rock???

Cactus Rock???

Someone awhile back was going to cut open a rock and report on what they found.
I never did see anything posted about that. So yesterday I had some idle time and thought I'd give it a whirl. The first batch of rocks that I cast when I started all this madness are still very heavy and just feel too dense, compared to others I've cast after them.

This rock was cast back in the first part of March this year. It was left in the mold for a week. Then it was soaked in tap water (changed every few days) for about 6 weeks. Last week, I took this batch out of the water and left them to dry out on a table outside. It has not rained on them at all. They are exposed to direct sunlight for half the day. Temps have been in the 70s and 80s since they've been out of the soak water.

After a week of drying out in direct sunlight, the very dense/heavy ones still had wet spots under them - irregardless of the conditions stated above! I thought this was rather odd, so I would cut one open to see why this was, and why it was so much heavier than the others. But first, there was this salt deposit on the underside of the rock; where most of the water oozed out. And yes IR, I did taste it this time and its salt for sure

Here is a close up of it.
After 8 weeks soaking in water, it's pretty obvious what is going on inside still.

This rock is the main culprit.
It's about 18" wide by 10" tall at its tallest and almost twice as heavy as similar sized rocks that have come along after it.

So I chopped it in half.
As you can see, the inside is much darker than the outer surface.
It is still very damp inside.

It is very porous on the inside, due to the rock salt.
If I had to guess, I'd say the interior is probably 60% void area and 40% mass. This exposed area shown here is about 3" tall. But notice that the core area is still mostly solid salt crystals. After two months the water soaking has only 'melted' away the outer inch or so of salt. Very strange!

Here is a tighter shot of the above.
Notice the crystals and water still flowing

Here is the same piece at a different angle.

So, I still don't know what to make of this rock. Why it is so slow in releasing the salt. It almost seems like the soaking water is not penetrating through to the core. This batch was mixed in the exact same proportion to the others that have totally dried out and are almost as light as balsa wood.

The only thing I can think of that is different about this first batch is that I did mix it a little more loose than those that followed. It wasn't soupy, but it was on the verge of not wanting to stand on its own when I would plop a gob of it into the mold box.

I call this my Cactus Rock
The only thing I can think of doing it to toss it into some boiling water for a few hours and see what happens. Right now, I've put it back into the soaking water. With it cut open and all, maybe that will set things in motion quicker.

Anyway, sorry to ramble on about my drivel, but I found this oddity to be interesting.
I know, I'm very easily distracted

 

[Insane Reefer]

Wow, Guy. Very cool.
It looks extremely dense, like the cement was mixed a bit too heavy on the cement, and too heavy on the water. You say it is only about 3" across the core? That isn't terribly thick - I've made a few pieces larger than that and had no trouble.
It also looks like this pieces was sort of "packed" solid. The chaotic cracks left when rock is lightly cast help with rock porosity.

The only times I have ever had problems getting salt to release were when I either used cold water to release, or if I let the rock sit too long - the rock in question was almost 2 months old. I'm now a big fan of releasing the salt within a week of casting, using really hot water. Depending on the size of the rocks, usually they will be mostly clean of salt after a day or two and 3 or 4 water changes.