The Ultimate DIY Rocks!

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Does any one know of a concrete mixture more like a clay consistency?
I was thinking of trying plastic cement,
It is what is used for the scratch coat with stucco
Thanks
Ken
 
<a href=showthread.php?s=&postid=7522026#post7522026 target=_blank>Originally posted</a> by Rhodophyta
Put a broom finish on it.

Would that "loosen" it inside though? The "shiny" doesn't bother me, in fact, that will only speed to colonies of coraline grow, since they grow on slick surfaces before rough. My problem is this stuff is dense, almost like china, even with sand/cc mixed in. If I want to sell/use the white rock, I have to either be able to know that what I am selling is beneficial to the purchasers tank, or that is is not, and should only be used ornamentally. I'm really conserned that the salt isn't releasing, except on the very surface :confused:

I'm playing with the idea of fascades - the big disply rock "Nessy", is a shell for base rock, or I have a tester I tried "painting" the white onto - sort of looks like sugar frosted mini-wheats, lol.

The idea is to cover the ugly grey with a brighter finish that will, over all, brighten the tank.
Is it just me, or does anyone else think that grey cement reefs look "dingy"? Even years later, when coverage is as complete as it will get, there just seems to be a dingy overall effect. JMO.
 
I don't want to stray too far OT with a question/idea/thought, but here goes:
Could a white sand be used as the mold? It would stick to the outside of the DIY rock, add a whiter/brighter appearance.

I know that there is some debate about using silica sand in reef aquaria, I'm not sure I understand all the issues. (If someone can fill me in or link me to an appropriate page for info, thanks!)
I have lots of that (silica) on hand from several years of cichlids, that has always been my substrate of choice
Could I use that in/on my DIY rocks to prevent the grey drabs?
 
IR, try to entrain air into your mix with a aerator, that will create voids in your mix. The key then is not to vibrate (bang around) the mix too much because that will cause the air to escape the mix and filling in the voids.

When you see them pour roads you see a machince that runs across the top of the pour and it vibrates the air out of the concrete to make it stronger. In your case the strength loss due to voids isn't an issue since it will be strong enough for your needs.

To all,

Make sure you dont add alot of water to your mix becuase the water to cement ratio will be messed up and you will get a brittle result. Make it dry so you can work it and just cover the piece to trap the moisture in. Conrete generates heat during the chemical reactions during the Kuring process which will evabroate the moisture out. We normally put a curing compound on the concrete to trap the moisture into the concrete. In the old days they would submerge the roads in water (basically flooding the streets) after the surace had set (turned light gray - in about 2 to 4 hrs, depending on temps)

I posted a article about using Fly Ash in the mix to make it strong and to reduce the about of cement used.

When using sand boxes for molds make sure your sand is totally saturated or it will suck the moisture out of your mix. Once the piece is set (light grayish) you can submerge it to help control the internal generated heat which will help prevent it from cracking.
 
This thread is definately building fast. Keep it going.

I am about to get my first batch started tomorrow. I hope they look good. I am trying the 4:1 salt/cement mix. If it turns out good, then I will try more shapes and sizes.
 
Most of the debate over silica sand dirives from partical size and lack of buffering capacity. Since cement contains silicates (correct?), there isn't too big of an issue on that count.
I think I remember reading somewhere were there was some thought as to algae bloom being linked to silica sands, but not sure if that is true.
 
<a href=showthread.php?s=&postid=7526059#post7526059 target=_blank>Originally posted</a> by Savatage
This thread is definately building fast. Keep it going.

I am about to get my first batch started tomorrow. I hope they look good. I am trying the 4:1 salt/cement mix. If it turns out good, then I will try more shapes and sizes.

After some experience with this, I would DEFINATELY suggest going for a 3:1 salt:cement mix. That worked much better for me. I might even go close to 2:1 next time.

Just a thought. Whatever the case, it is SURE a whole lot of fun! :)
 
Batch 2, after about 4 days soak. I do like them better than version 1. Batch 3 is setting up in a salt mold, as I type.
This is fun!

Batch 2, top view
P1020102.jpg

Table
P1020106.jpg

small cave
P1020104.jpg

bigger cave
P1020105.jpg

Link to batch 1, didn't want to dbl post them
http://reefcentral.com/forums/showthread.php?s=&postid=7477235#post7477235
 
approx 2.5 to 3 parts salt to 1 part cement. No sand
I did use some sand in batch 3, will post pics & details after they set a few days
Thx for the compliment!
 
<a href=showthread.php?s=&postid=7525662#post7525662 target=_blank>Originally posted</a> by Stumpydru
IR, try to entrain air into your mix with a aerator, ...

While it is wet/being mixed or during the kure?
 
Oh, and a few were talking about crumbliness...
Because of the salt, you are going to end up with membrane thin places in the cement, particularly on the edges. These will undoubtedly crumble with handling, and is normal. One thing I do once the salt is mostly gone, is take a piece of hardwood, like dowel or tool handle, and rub it briskly, but lightly over the surface of the rock, nocking off anything that is ready to come off anyway. What's left behind is usually pretty solid and non-crumbly.
 
Based on experience with silica-based sands, it is not a good idea. I had terrible algae blooms until I siphoned out all of the sand from the tank.

Regarding the "parts" mentioned in seemingly all of the formula posts, does this refer to volume or weight?

Can someone simplify the formula for making this into x number of cups of cement + x number of cups of salt + x number of cups of water and then variations, using oyster shells, etc.? I realize that the water component can vary, depending on the particle size of the salt, so that should be kept in mind for any formula like this.

Also, I made a couple rocks using the "Mud" mixer from Home Depot (see page 5). Does anyone think that this is too aggressive and will cause the salt to dissipate during the mixing phase?

Finally, at which point does the "cure" stage turn from curing the concrete to curing into live rock? i.e. when should the created rocks be moved from hose water to sea water with pre-cured live rock introduced to "stock" the new rock with bacteria?

Mixing and forming the rock is one thing, but perhaps a summary of the whole process, including the point of safe introduction to the tank, would be in order.

Thanks,

Jamie
 
<a href=showthread.php?s=&postid=7528393#post7528393 target=_blank>Originally posted</a> by slalomskier49456
Based on experience with silica-based sands, it is not a good idea. I had terrible algae blooms until I siphoned out all of the sand from the tank.

Once again, all these experiences are anectodtal. And from my anectodtal experiences, I have never encountered such a problem. Maybe I'm lucky. Maybe skier is unlucky. For further information, I recommend that everyone reads this article.

SILICA IN REEF AQUARIUMS by RANDY HOLMES-FARLEY, Ph.D. - http://advancedaquarist.com/issues/jan2003/feature.htm

Regarding the "parts" mentioned in seemingly all of the formula posts, does this refer to volume or weight?

By volume.

Can someone simplify the formula for making this into x number of cups of cement + x number of cups of salt + x number of cups of water and then variations, using oyster shells, etc.? I realize that the water component can vary, depending on the particle size of the salt, so that should be kept in mind for any formula like this.

See above comment. For example. If the mixture is 3:1:1 of some sort and you decide to use cups, it would be 3 cups of X, 1 cup of Y, and 1 cup of Z.

Also, I made a couple rocks using the "Mud" mixer from Home Depot (see page 5). Does anyone think that this is too aggressive and will cause the salt to dissipate during the mixing phase?

If mixed too much, yes. But unless you sit there and stir it for an excessive amount of time, all you will do is just have smaller holes in your rock.

Finally, at which point does the "cure" stage turn from curing the concrete to curing into live rock? i.e. when should the created rocks be moved from hose water to sea water with pre-cured live rock introduced to "stock" the new rock with bacteria?

First, we have to "cure" the rocks by letting them harden. I'm unsure the actual time for properly cured rocks. I just wait 24 hours without additional added moisture since I'm not building a house or road with my rocks

Then, they get placed in freshwater until the pH drops to a safe level of about 8.3. This can take anywhere from 4-6 weeks. Occassionally longer. Water changes definitely help speed things along

Lastly, when everything is settled down in the "kuring" tub, you can add them to your tank. It can take up a few months to see outward differences. Inside, it can take six months to a year to have a healthy culuture of bacteria. It's just like using base rock.

Mixing and forming the rock is one thing, but perhaps a summary of the whole process, including the point of safe introduction to the tank, would be in order.

It is all listed in this thread, but summarized above for you

Thanks,

Jamie

You're welcome :D
 
Thanks a lot! Your promptness in response is impressive.

Since you are talking volume, the cups thing becomes obvious, but still, thanks for spelling it out.

Threads can become long and evolving. I have noticed that what was once clear can become convoluted as good ideas surface. I appreciate a good summary or best-practice every so often for clarity. I only wish our engineers could respond as quickly as you did...even anecdotally

Regarding the silica sand, I thought it would be great to use a little beach sand from our Lake Michigan Beach (sentimentally) on one end of the tank, but didn't think about the fact that Lake Michigan beaches are silica-based until I had the tank going. Who knows, the algae blooms could have been related to something else, but they did stop when the sand was removed.

Thanks again!

Jamie
 
I should clarify the sand thing--I didn't, technically, have algae blooms. I had major cyanobacteria breakouts until I got rid of the sand. Cyanobateria is definitely different than algae.

-J
 
<a href=showthread.php?s=&postid=7528617#post7528617 target=_blank>Originally posted</a> by slalomskier49456
I should clarify the sand thing--I didn't, technically, have algae blooms. I had major cyanobacteria breakouts until I got rid of the sand. Cyanobateria is definitely different than algae.

It is MUCH more likely that your cyano "blooms" were not due to silica based sand and much MORE likely to be do to lack of proper water flow causing nutrients to sink into your sandbed. Were you doing proper water changes? Did you have a good skimmer.

All important questions.

From what I have seen, Cyano "problems" are more often then not do to other issues with the system, and not silica based sand.
 
<a href=showthread.php?s=&postid=7528579#post7528579 target=_blank>Originally posted</a> by slalomskier49456
Thanks a lot! Your promptness in response is impressive.

Are you saying that I have too much time on my hands? :lmao:

...So what if I do....

Just kidding. Your welcome. The "My RC" button and "Subscribe to this thread" link make promptness easy ;)
 
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