The Ultimate DIY Rocks!

[mdms]

hi ppls

just would like to say this is a great thread!

i while back there was discussion about the internal biological activity of these salt rocks.

well tonight , i snapt open a rock thats been curing for one month.

it appears internal salt partials have actually dissolved. Leaving voids of water.

this means the rock could be biologically active not only on the surface but also deep with-in. just like real live rock.

[goldmaniac]

Last night I got around to making my 2nd batch of DIY rock:

Ratio of 1 : 1 : 2

1 part Portland Cement
1 part used refugium sand, which was mostly Kent's BioSediment but also had some Mineral Mud, which is various particle size
2 part rock salt

mixed cement and sand with water, created a stiff mixture, then folded in salt.

initial appearance was much better, texture identical to actual rock.

It was easy to use, mold, pour, etc. it was smooth (sand) and also stiff at the same time. good consistency to work with.

i'm afraid that I made some big, oblong pieces, though!! I just got on a roll of 1) dollops of cement, 2) fill around cement with fill salt, 3) repeat.

haha

I'm gonna wait a week before looking at these pieces. Will post results.

Meanwhile, my 1st attempt 3:1 salt:cement has withstood the test of time. I'm keeping it in 5-gal bucket, and handling often. Initial test piece, after all. After the initial tiny surface pieces have broken off, the thing is surprisingly strong. I may use it in the tank, after all, after kuring. <-- "kuring" is sitting in H2O to reduce pH, as opposed to "curing", which is the cement hardening. Just repeating terminology that's been decided in this thread.
-G.

[Travis L. Stevens]

Originally posted by mdms
hi ppls

just would like to say this is a great thread!

i while back there was discussion about the internal biological activity of these salt rocks.

well tonight , i snapt open a rock thats been curing for one month.

it appears internal salt partials have actually dissolved. Leaving voids of water.

this means the rock could be biologically active not only on the surface but also deep with-in. just like real live rock.

That's what I've been trying to convey all along Thanks for sharing your experiences with this. I plan on possibly breaking open one of my rocks that has been in my reef for about a year to see what real life is in there.

[GuySmilie]

Originally posted by Travis L. Stevens
That's what I've been trying to convey all along Thanks for sharing your experiences with this. I plan on possibly breaking open one of my rocks that has been in my reef for about a year to see what real life is in there.

Same here Travis.
Someone was chastising me awhile back when I offered that the salt crystals form a honeycomb effect, thus allowing fluids to flow through the rock, thus dissolving all the internal salt. They said the cement did not get wet in the center. Looks like we were right after all
Will be curious to see what you find living in there!
Guy

[Travis L. Stevens]

Agreed Guy. It's weird that people will still disagree with me sometimes when I've done it.

[gary faulkner]

Originally posted by Travis L. Stevens
That's what I've been trying to convey all along Thanks for sharing your experiences with this. I plan on possibly breaking open one of my rocks that has been in my reef for about a year to see what real life is in there.

Bust it open, Travis, inquiring minds want to know.

[Travis L. Stevens]

I'm about to move, so I'll need to empty out my tank. It shouldn't be too difficult.

[thriceanangel]

I set some rock that had been curing for a month on my basement floor because I wasn't ready to add it to the tank. There was water coming out of it 2 days later. My wife actually thought that the dog peed on the floor! I had to tell her that the rock is still draining. Gotta be some good anaerobic activity going on deep in the rock.

[thriceanangel]

Of course it was 2 pieces that weighed close to 20 pounds a piece.

[GuySmilie]

Same here.
I had a good fist-sized chunk that I pulled out of the soak bucket and left in the sink one evening.
A few days later there was still a trail of dampness between it and the drain. It kind of startled me at first as I thought someone had been in the fish room messing around with my rock. Then it dawned on me where the moisture was coming from.
Guy

[mdms]

i put some extra thought into this.

it may take some time for the salinity of the water voids within the rock to stabilize. because i guess its harder for the salt to disperse.

so i placed the batch of rocks into the oven at max heat for 2 hours.

i found cyrtals forming on the surface ( this could be the salt with in escaping tot he surface)

also the heat evapurated moisture from with in the rock.

i then snaped the oven dry rocks to find voids inside the rock completly hollow, dry and some crystals formed on the inderior walls of the voids. ( this is most likely salt)

so overall. i think the concrete rocks are more pourous allows more flow thru than previously thought.

[goldmaniac]

Awesome

this stuff might actually be better than real live rock, I bet it's more pourous

Travis should get ThOTM for this



BRILLIANT!!

[Insane Reefer]

Oven curing is how the big commercial brick and block makers can make so many bricks so quickly. In a pressurized, very damp oven the bricks are cooked at 400°F for a couple of hours - and this completes the cure stage.
This follows the "Q10" temperature coefficient.

The crystals you are seeing could be ettringite. Ettringite forms as rod-like crystals in the early stages of hydration. I had some up to an inch long when I pulled my last toilet kures out.

Or, it could be the salt

And you haven't discovered anything new. Travis once said he had a rock that floated - doesn't get much more porous than that.

Thanks for posting about the oven though - I've been trying to figure out a DIY cooker, to no avail; I think that if one could maintain a temp of 100-150°F, the rock would cure in 2 weeks. Still have to kure it, but boiling seems to really draw out the crud rather quickly, doing some tests on whether this brings the pH down quicker.

[Travis L. Stevens]

Well, I have good news and bad news. Which do you want first? Just kidding, you can't choose

Bad News: Okay, here's the bad news. It's going to disappoint some of you. I had to move my tank since we moved on short notice this weekend. I didn't get a chance to break any rocks open, and I've already aquascaped things back into place. I'm NOT going to dig it out again.

Good News: Now here is the good news. I kept a good visual account of what I could find on the rocks and in the nooks and crannies. In the end, the DIY rock had more life apparently on the outside than the real live rock. On the other hand, the superior caves of the real live rock harbored larger animals in smaller concentrations. Here is a detailed list of what was found on the DIY Rock

Munnid Isopods
Copepods
Amphipods
2 different Feather Dusters
Collonista Snails
Stomatella Snails
A HUGE population of Rissoid Snails
Lots of Bristleworms
Spirorbid Worms
Vermetid Snails
and I have had one Chiton from the beginning that has gone from 0.5" long to about 2" long, and it was found on the DIY Rock and not the real live rock.

So, needless to say, while I wasn't able to find the time to delve into the insides of my DIY rock, it is sufficient to say that the DIY rock on the outside is highly comparable. I'll try to get pictures of all the critters I've now exposed from the move.

[mdms]

sounds like good news.

ok .. so i think the random network of tunnels of real live rock can be formed using spaghetti pasta or even by drilling. even tho it will take a very long time to dissolve. and may have to eaten out by (critters)

however as a whole. this is very good news for the
"DIY LIVE ROCK MOVEMENT".

cant wait to see pics of when the rock is crushed open.

i think we are all wanting to know:
1. what kinds of animals reside inside?
2. does it have the same strong smell as real live rock when it is crushed?

[Azazael13]

for random network I use thick weed eater string and poke it through my rock after it has been sitting for about an hour.

[Insane Reefer]

MDMS, I can answer at least part of your question. When pulled out of a system and broken, they smell the same as the real thing, and have things like worms and bugs all through them...

The animals don't know that they aren't looking at real rock - they just see crannies and tunnels and "home".

[Insane Reefer]

Hey folks.

I've been a busy little research bee, and have learned a LOT about cement. I went so far as to contact Cement.org with a persistent question I came up to; C02.

Anyway, I received a reply the next morning, and since this is really interesting, I will post the emails here, slightly altered for length and irrelevant content.

To whom it concerns,
I am currently doing research for Man-Made
Reef Rocks, also known as Aragocrete. Simply put, these are a man made
alternative to the real reef rocks that are harvested from our oceans
for the marine aquarium hobby trade.

Man-Made Reef Rocks, or "Live Rock" as they are known in the hobby, are
made with a mix of portland cement and a variety of natural products
such as sand, crushed coral rock and even solar salt. The rocks thus
made, are allowed some time to cure, then are soaked in water for several
weeks to several months, until the pH of the soak water comes down to
an acceptable range of 8.0 - 8.6.

I am writing you in the hopes of clearing up a question I have.

In my research, I have seen it mentioned that it is not actually the
water that causes the cements curing or hydration phase, but instead that
it is the Carbon Dioxide in the water that causes the actual chemical
reactions. From what I gather, the cement completes its hydration by
exposure to carbon dioxide.

Can you please substantiate this and possibly elaborate on it, or
debunk it if it is not true?

It has also been a matter of hearsay in the Man Made rock community,
that during the soaking phase, one could add a carbon dioxide feed to the
soaking tank to more quickly complete the natural curing process. It
would be nice to be able to prove or disprove this theory once and for
all. Do you know if this would indeed work, and if this is indeed the
case, how much
C02 would need to be added, in Parts per Million, to significantly
accelerate the process?
----------------------------------------------------------------------------------

The reply, from a real concrete construction engineer...
----------------------------------------------------------------------------------

The chemical process called hydration that produces strength gain in
portland cement based concrete materials is a reaction between the water
and the cement. The definition of "curing" per ACI 116, Cement and
Concrete Terminology is,"action taken to maintain moisture and temperature
conditions in a freshly placed cementitious mixture to allow hydraulic
cement hydration and (if applicable) pozzolanic reactions to occur so
that the potential properties of the mixture will develop." In short the
water chemically reacts with the cement to provide the strength
properties. This reaction also requires that a reasonable temperature of the
material be maintained, typically in a range between 40°F and 90°F.
After a reasonable moist curing period of 3 to 7 days the concrete will
typically achieve a strength appropriate to your application.
The second question is how to reduce the pH of the concrete material to
an acceptable level to be placed in an aquarium so that the pH of the
water will not cause problems for the fish. There is more than one
approach to this part of the process.
The first and most common would be to continue the moist curing for a
sufficient period that the concrete has become so dense that the
alkalinity of the material can not be leached from the matrix, and the
alkalinity of the near surfaces ahs been leached from the piece. This usually
happens somewhere around the 30 day mark, and has the benefit of
allowing further cement hydration giving the material a higher strength than
materials that are air dried. It is also appropriate to begin to
provide a fresh water bath (exchange the water in the curing chamber) at
around 2 weeks of age and every few days after until curing is complete.
Another approach would be to moist cure for 3 to 7 days and then alter
the pH of the concrete material by exposing the surfaces to CO2 gas.
The CO2 gas reacts with the calcium hydroxide produced by the cement
hydration process to produce calcium carbonate which has a lower pH than
the original concrete mixture. Since CO2 gas occurs naturally in the
atmosphere, simple air drying will do this over time. The problem is that
it will take a very long time to carbonate the surface. In practice if
you wish to accelerate the process you would need an environmental
chamber so that the concrete could be exposed to pure CO2 gas under a
pressure environment. While this might be effective, I'm not sure that its
worth the trouble to design and operate such a chamber.
Your suggestion for providing CO2 in the water may have some technical
problems. Combining CO2 and water produces what is commonly used as
carbonation for soft drinks. This combination of material is typically
referred to as carbonic acid which when placed in contact with hardened
concrete causes slow disintegration of the concrete surface, and as the
concrete surface is stripped away a fresh layer of highly alkaline
concrete surface is exposed.
My best recommendation is to use the thirty day curing method; the CO2
gas would be effective for someone who is mass producing these precast
pieces but requires a pretty sophisticated methodology; and finally I
would not consider the CO2 in water as this produces an acid that
attacks the physical structure of the concrete.

[Insane Reefer]

v4.0

Hey All,
I'm going to post my favorite tips and links every so often so new people can find it all pretty easy. It is a summation of the most commonly asked questions and things I have picked up through making my batches. Some I’ve gleaned from this thread, others I’ve learned from past mistakes and experiments. I've been making DIY man-made rock or aragocrete off and on for close to 8 years. Lately, I have even made some money on my rocks

I thought I’d pass this info on – maybe save someone some frustration or spark a new idea.

I will continue to refine and update this post as more info is added, and repost every so often.



First, good info can be found at these two places - I think everyone who wants to make rock should read these in full. One of the articles gets pretty heavy handed with the science/chemistry aspect, the other babbles on tangents once in a while, but both are worth the read, IMO.
ARAGOCRETE RESEARCH BY TRACY GRAY
Reef Propagation Project:

And this link is for Cement Colorant – I’ve spoken with the vendor and am assured that, given our kure process, this stuff will be safe and colorfast in the aquarium. They sell it in small amounts in rainbow colors and are very cheap.

List of Aggregates
Sand - caribbean/aragonite is best, but very hard to find. Toys R Us carries a play sand that a lot of folks use and report no trouble with. Limestone sand has gotten good results as a DSB, so should also work.
Crushed Coral - AKA "CC". Makes nice, realistic rock, but expensive
Crushed Oyster Shell - AKA "OS". Any shell will work, but OS is very cheap at feed stores.
Salt - Many thanks to Travis Stevens for figuring this out! The salt of choice is "Solar Salt Crystals", typically found as a Water Softener Salt. 99% pure salt. Get the coarsest crystals you can find. Solar Cube can be used, but is sort of chunky - makes nice holes though. Boiling the "cubes" rounds off the edges and makes nicer holes. Solar Pellets can also be used, same as Cubes.

Rock Recipes
Ingredients are measured by volume, not weight!

Original Recipe: 4:1 - 3:1 / Salt:Cement
Improved Recipe: 3:1 - 2:1 / Salt:Cement
Ol' Skool Recipe + : 1: 1.5 : 1.5 :1 / Salt:Cement:CC&OS:Sand

Molding Material
Really, pretty much anything that is dry and crumbly will work. I've even used stuffing bread crumbles, but that draws bugs while it dries.

Soil
Salt
Sand
Clay

A certain portion of the molding material will remain on the rocks - this can usually be removed with a short acid bath, followed by a good scrubbing with a plastic or fine wire, bristle brush.

If you use Rubbermaid or Tupperware, you can reuse molding material over and over again. Line cardboard boxes with plastic to prevent moisture leak and wall collapse.

DO NOT Wet Salt, if it is used as a mold material - this means when working with salt, do not add water to the casting box as you would or might with say clay or sand.

----------------------------------------------------------------
Now, I will list my tips and tricks, in no particular order. Many will seem stupid or like common sense, but you don’t know about some people’s kids, lol…

Tips and tricks

1. Wear gloves when making rock. If possible, don’t let the cement get on your skin, especially the dry powder. If possible, wear a painter’s mask when measuring and mixing dry cement; this stuff can really burn the inside of your nose.
2. Setup your work area in advance; cover surfaces with plastic or old sheets if needed (like in your kitchen or living room). Fill casting containers with whatever mold material you are using, or have it standing by within easy reach. Give yourself walkways if you are making a lot of rock – nothing sucks as much as trying to create enough work space after the fact.
3. Think about the weather for not only the day you cast, but the next few days as well, if you plan on doing this outside. Rain can make a mess of things…
4. Use Portland Type I, II (I/II) or III – these are known to be safe for use and make rock with proper porosity.
5. Mix all aggregates excepting salt into the cement before adding water. Add salt after you have reached the right wet consistency, and mix it in lightly – the less salt is leeched off the grains of salt, the stronger your final rocks will be. Water softener salt of the type “Solar Salt Crystals” works wonderfully (Thank you Travis Stevens!).
6. I prefer to use crushed coral and sand in my rocks for long term strength, plus salt to add porosity. The aggregates also give realistic details to the rock. My preferred recipe is 1.5 part cement + 1.5 part sand + 1 part crushed coral/shell mix + 1 part salt, but this is expensive to make. You can also use a mix of 1-1.5 cement + 1-2 crushed oyster shells + 1-2 salt.
Mainly, a 1 part cement to 3-4 parts “other” is acceptable, whatever you want to mix together is up to you and you should be ok if you follow the 1:3-4 part rule.
7. Work in layers for added dimension. If you lay a layer of molding stuff in your container, make a few divots in this molding layer first, and add cement to these first to make lumps on the bottom, you can avoid flat bottomed rocks. Now lay the main part of your rock, adding molding material as needed.
8. You can make neat “cliff-face” striations if you take a handful of salt, and lay it just along the top edge of wet cement, forming a narrow line of salt along the edge, laying a thin layer of cement over the salt, and repeating this to form, on the outer edge of your rock, a sort of cliff that looks to be cut by water action.
9. Anything cast thinner than an inch is likely to break, unless you are careful with it.
10. Find a nice bit of stainless steel or aluminum wire – 2mm or so in width, and bend a handle for one end (remember you will probably be wearing gloves, so bend accordingly). As you cast your rock, use this wire to poke Lots of little tunnels all through the rock – all the way through if you can; this will make the rocks extra porous, and give bug life lots of places to hide and propagate in-tank, as well as allowing more water to move through the rock. Alternatively, you can cast the piece, and then poke as much of it as you can – though this way tends to look a bit contrived. I like the first way better.
11. Once your rock has cured and it has been curing for about a week and if you made it mixed with stuff like crushed coral or shells, mix up a weak acid mix and scrub the outside of your rocks with a stiff bristle brush. Be sure to take proper precautions when working with acid – not only from burns, but from fumes as well!!! If you only made your rock with salt and cement, ignore the acid wash, as your rocks will dissolve, but still give them a vigorous scrubbing - this will loosen the weakest stuff and get rid of it without shedding it all over your tank. If you have shells or coral, this can make the surface even more porous, and clean cement films from shells and the like that might be on the surface. I use a mixture of 1/2c muriatic acid added to 2c water.
12. You can make “lock together” pieces by wrapping a bit of PVC in something like tissue paper or plastic wrap, sticking it in the wet cement of “part a”, and then laying plastic wrap over and around the fresh cement/PVC, and then cast “part b”, making sure to get a good fit around the PVC join. I find this works, but I personally have an easier time if I cast “part a” with PVC set into it, let it cure, then wrap it well with whatever, and cast “part b”, and I can cast really large pieces this way.
13. “Cement Paint”. You can make up a slurry of cement and sand, say 1 part cement to 2 or 3 parts sand, made fairly thin and fairly wet and sloppy, and use it to decorate rock with “coralline algae”. I use white Portland, but I don’t see why white grout or mortar wouldn’t work as well. You can use cement colorants to color the cement any shade you desire. Working with a paintbrush, you can easily replicate the swirling patterns of coralline. I’ve also used this mix to paint/dry brush grey Portland rocks to white.
14. Branching rock/Coral skeletons. Pick PVC pipe a bit thinner than what you want your final piece to be. Cut into appropriate lengths, cutting one end flat and the other at an angle. Drill plenty of holes in the PVC to help the cement stick on. Drill extra holes on the very end that will allow you to tie the pieces onto the “main branch” with zip ties. You can bend PVC into believable shapes using heat from either a propane torch or a heat gun, and a couple of pairs of pliers (use appropriate precautions). After you have your PVC framework, mix a thicker blend of Cement Paint (less water, more cement) and paint/dip the skeleton, covering completely. I recommend hanging to dry, and dipping several times, using a paintbrush to smooth it out and prevent weird drips. When done coating, tie a grocery bag around the hanging piece to preserve moisture and allow to cure 48 hours or more.
15. Think about how corals come to you, as frags and whole colonies, and think about how hard it can be to attach these in your typical rock pile. Flatter surfaces and shallow bowls in larger rock shapes can make latter placement easier.
16. You can make rock “shells” if you want to avoid the rock pile look altogether and these are only limited to your imagination and size constraints. You can stuff the cavity in the back of this hollow construction with cheap $1.99/lbs rock, or whatever you want. I DO NOT recommend making these with the cement and salt only recipe! Make a form of some sort (use your imagination), put it in a box that will fit into your tank (making a rock too big for the target tank blows), and secure it to one side, or more (for multi-part casts) with duct tape. Line rest of box with plastic. I made my form from plastic grocery bags stuffed into a garbage bag, with a little air added, and taped that into the target box. Slowly build the shell wall (adding details as you wish), filling the box with salt/molding material, until you have the form covered with a fairly uniform covering of cement. LEAVE ALONE FOR A WEEK! Cover with plastic if you can.
17. Frag Plugs. If you have extra cement at the end of the day, make frag plugs by using a mini muffin pan, and filling with ½in. of cement. Spray the pan with cooking spray for easier release. These can be put in a mesh bag and cured in the toilet tank.
18. Hate scraping the back wall of your tank? You can make thin wall covering sheets that can be glued with silicone to the back wall of your tank. Alternatively you could make shelves along those lines. I find casting on a sheet of glass covered in plastic works best for this. Also marking out the actual measurements of the back wall onto the glass helps to avoid sizing issues. I DO NOT recommend using the salt and cement only recipes for this application, nor the use of any salt at all! I also mix this just a little wetter than I normally use. Once you are setup, just drool the cement onto the covered glass. I tried doing large sheets, but these mostly were too weak to hold up. I find making smaller pieces (12inX12in or so) that abut like a puzzle work best, and sort of give the illusion of looking at a cracked and crevassed reef wall. After you cast these, they need to be kept moist and unmoved for 3 days. Believe me. They do. And you will need to mist them once a day. I just covered mine with a garbage bag and used a water bottle to mist it. I recommend an acid wash, as described above, once these have kured for a week.
19. If you make a rock or rocks you don't like, either use fresh cement mix to add some new bits, or break the rock up and use it as aggregate in your next batch - no waste is good
20. The moister you can keep the cement while it cures, the harder the final rock will be - try wrapping it in a bag, or misting it while it cures. Supposedly, if you can let it sit for two weeks before starting to kure, it will dramatically speed the kure time.
21. Dust your molding sand with oat flour for easy removal of surface sand. Thanks Rhody!
22. Mix molasses with your molding sand to give it more texture. Thanks Rhody!

Various things I have used and have worked for me for adding details:
1. Cemented Nylon String. Makes realistic tube worm/duster tubes. Make a thin paste of just cement, and dip small lengths of the sting in. Wipe excess off between fingers and lay onto the rock in desired figure.
2. Veggie Capsules. These can make little tunnels when laid end to end in the wet cement, and then covered with more cement. Or poke into outside edges to mimic polyp holes. Do NOT mix into the cement mix.
3. Nori Sheets. These can be wetted and formed into shapes or rolled into tunnels.
4. Balloons. Both the round and “animal” ones work. I find that filling them with water makes them stronger. Doubling them up works well too. Make sure that you can get the balloon out afterward - i.e. leave the knot sticking out.
5. Cardboard Rolls. Can be cut to form bracing, tunnels or for pillar shapes. Be sure to use it in such a way as will allow you to remove it after a few days of kuring. Hemostats work great for grabbing a-hold and pulling it out.
6. Tissue Paper. The white stuff you find in gift bags. Disintegrates quickly during kure. You can make little (or big) “salt bags”, that you can lay into the middle of larger rocks to give more holes for ‘pods and the like. Can be used to make caves and tunnels. Just use a small bit of paper, lay some salt in it and twist or tuck the ends – a small bit of cotton thread could be used to secure the package too.
7. Pasta. Must be cooked “Al Dente” before use. Do not mix into cement, it only makes a mess and is a pain to get out of the rock as it gets really hard and crunchy when the rock dries (ever scraped 3 day old pasta off a plate?). Use to add spaces in the rock, or tunnels with spaghetti (at your own risk). Rigatoni adds a nice effect if placed just right.

Things that DO NOT work:
1. Vinegar/acid kuring. Waste of time. Lowers initial pH, but pH will then later spike.
2. Bio-degradable packing peanuts/Cheesy-poofs. I can find no way to really use these that is also safe for the tank.
3. Fish food pellets. That was really, really nasty. I don’t want to go there.
4. Uncooked Pasta. As pasta absorbs water, it expands, causing the cement to fracture and crack – cook it al dente if you really want to use it.
5. Alka-Seltzer . Doesn’t work. It dissolves to quickly.
6. Yeast. Doesn't work. pH kills the cells before they can respirate. Though during the Kure, this might be a speed option.
7. Co2. Ok – it does work, but only under high pressure. Adding into H2O will only make soda pop, and eat away at your rock.


Rock Kuring
Kuring your rock is the next hurdle. It is really, really best to leave your rock alone for at least a week before starting this step. According to Quikcrete reps, it takes 7-14 days for the rock to stop curing/hardening (though this process is actually going on for a lot, lot longer) - even though it looks and feels done. Testing standards say it takes 28 days to reach full strength and before testing for commercial applications can commence. By putting your rock in the kure bin too soon, you are wasting a lot of water and making weaker rock. Rocks during this 2-4 week period will naturally loose pH - from 12-13 at casting time down to 9-10, with NO WATER USED. I theorize that rock left longer, like 8 weeks, will only need a few weeks of kure time (and lots less water!).

Kuring is pretty straight forward. Lots of time, and lots of water changes with adequate water volume, unless you have access to a reasonably clean waterway. Powerheads help force water through the rock and help the insides kure out. Adding heat to the bucket, upwards of 90°F will speed things along.

When your bucket kured rock quits leeching out white scum on the surface of the water, and stops leaving a white residue on the bottom of the bucket, you can start checking for pH. Rock has been known to kure in as little as 2 weeks, but most bucket kured rock takes 6-8 weeks to reach safe levels – some will take up to 3 months. Be prepared to wait.

To properly test for pH, change the water – either use RO/DI or aged saltwater. Let the rock sit in this for 4 days without air or powerheads – you want still, stagnant water for this. After the 4 days, give the water a bit of a stirring and check pH with appropriate test kit. If it is in the acceptable range of 8.0 to 8.6, it is probably safe to use. If not, continue to kure.

If adding your rock to a newly established tank, you can go ahead and put it all in at once. If the tank is older, with inhabitants, you may wish to add a rock or two at a time, to allow the system to “settle” between each addition.

Expect an algae bloom.
A few people, those who either have waterways to kure in, or those with really butch systems have reported no algae blooms, but I suspect they are the exception, not the rule. If your tank blooms, don’t panic. Most tanks bloom within the maturation period anyway. Double check your system for things like NO2 and NO3, and other algae causing symptoms and correct anything that isn’t up to snuff. Take all the normal steps to curtail the growth, but then just ride it out. If the bloom is caused by the rocks, the algae will soon deplete the readily available nutrients and starve itself out. If it doesn’t go away within a few months, then you should check into other reasons for the bloom.

Well, I think that about covers my repertoire. I apologize for the length of this post, but hopefully some of you will find something of use…

I encourage the rest of you to take some time to write up your experiences and tips and share them with us – by sharing our experiences, we all learn and get better and better at making our own rock.

Good Luck, and Rock On!

[BigSkyBart]

Travis,
glad the move went well for you & thanks for the livestock report from your rocks.
Sounds like they work pretty darn well!

IR,

great idea & kudos for getting that info from the concrete.org folks

[mdms]

great work insane!!!

i really like the summery you have put together!!!

i have heard about thorite and how polymer modified / self levaling / non shrink cements dont effect ph like portland does.

what are your thoughts on using polymer modified cements?

[Travis L. Stevens]

Just as a little summarization to the email that was sent back to Insane Reefer, when you add CO2 to the water to create Carbonic Acid, it is the same method that a Calcium Reactor uses to provide an aquarium with Alkalinity and Calcium.

Insane Reefer: Well, that definitely says a lot and nothing to me all at the same time. Or should I say that confirms what I've thought from the very beginning. My slightly refined process will now be as followed in another post.

BigSkyBart: Thanks. It's been hectic on moving, and I still don't have everything done. I got the 29g tank over, but I still need to get the 10g, the 75g, and the culture station moved over. Thank goodness the 75g is empty

[Travis L. Stevens]

Ultimate DIY Rocks
The Ultimate DIY Rocks are a way that an average reefer can make rocks for their aquarium at an affordable rate that is completely customizable. This style of man made rock has a special quality to allow it to be very porous so that bacteria can colonize deep within the rock to provide exceptional biological filtration.

Recipes
There are two recipes for the Ultimate DIY Rocks; High Strength and Low Strength. Typically the Low Strength Recipe will work in all general applications, but for some that plan on a special projects that will require lots of weight to be placed on a rock, the High Strength Recipe might be better.

Low Strength Recipe: (2:1)
The Low Strength Recipe capitalizes on the lightness and porosity of the rock to allow large amounts of bacteria to colonize the rock and to allow a little extra weight to be relieved from the aquarium itself. The Low Strength Recipe uses only two ingredients; Rock Salt (100% Sodium Chloride) and Portland Cement (Type 1). The ratio of ingredients should be 2 parts of rock salt to 1 part of cement.

High Strength Recipe: (2:1:1)
The High Strength Recipe is typically the same as the Low Strength Recipe, but an extra ingredient is added so that the cement has a little something more to adhere to. The recipe now has three ingredients; Rock Salt (100% Sodium Chloride), Portland Cement (Type 1), and Sand (Aragonite or Limestone based preferred). The ingredients are mixed in as 2 parts of salt, 1 part of sand, and 1 part of cement.

Making the Mixture
There is a special way to make the mixture in order to give the rocks their best strength. Dissolved salt can weaken the cement structure, so speed and technique is crucial in order to get best results.

• Step 1: Pour all the ingredients, except the water and salt, into the container you will be using to mix the recipe in. Mix these dry ingredients until they are evenly mixed throughout.
• Step 2: Add enough water to get the dry mix to the consistency slightly more wet than PlayDoh. It should be able to hold its shape, but squish between the fingers when you close your fist around it. If you get it too wet at first, add a little more cement.
• Step 3: Now carefully fold in the rock salt. You must work fast so that little salt dissolves from the water, but be able to work long enough to be able to get the rock salt evenly mixed into the cement. The end product should be able to hold its shape relatively easily.

Making the Rocks
In order to make the rocks, you need to be quick. The more you mess with the rocks, the weaker they will set. Unfortunately, cement isn't like clay. You can't take a lump of cement and sculpt it to make amazing structures. Instead, randomness or even multiple smaller pieces cemented together might be the best thing for you. Lots of preplanning is usually needed for amazing looking rocks.

Preparing the Rocks for the Aquarium
Now that you have mixed the recipe and made your rocks, you'll need to do a few things before the rock can safely be placed into an aquarium.

Curing Process: (14 Days)
Curing is a process that strengthens the rock. What happens in the cement is C-H-S bonds are made. First, when the water and cement are added the Carbon-Hydrogen bonds are made. This is what gives it the initial strength. Then the S part of the bonding happens when the C-H, now Carbon Hydroxide, bonds with the Silicate in the cement. What this means is that for the first few days after the rock is made, the rock needs to be moistened so that ample Hydrogen is available for the Carbon. You can moisten the rock by keeping it sprayed with water. After the initial curing, leaving it to set for the remainder of the 14 days will allow sufficient time for it to strengthen and lots of C-H-S bonding to occur.

Kuring Process: (30 Days)
Since we are not building a bridge with our cement, it isn't completely necessary to allow 100% C-H-S bonds to be created. In order to do this without the Kuring Process, it could take several months to complete. Instead, we stop the initial bonding prematurely. Because of this, extra Calcium Hydroxide is built up in the rocks, and when this comes out of the rocks in our aquariums, it could spike the pH to 12 and kill everything in the tank. In order to fix this, we submerge the rocks in a Kuring Vat, and letting them soak for 30 days. As the Ca(OH)2 leaches out of the rocks, it will cause the water to become saturated. Eventually the water will accept less and less Ca(OH)2 until it stops altogether when the water reaches the saturation point. To offset this, it is recommended to change 100% of the Kuring Vat's water every day. This usually gets most if not all of the extra Ca(OH)2 out of the rocks in the allotted amount of time. To tell when your rocks are ready for the aquarium, test the pH before every daily water change. If the pH stays at roughly 8.3 from the previous water change, then they have little Ca(OH)2 left in them, and they are ready to be placed in the aquarium. In this amount of time, most of the salt should have dissolved out of the rocks. Any left over salt deep within the rocks is safe for the aquarium. On a side note, the amount of time it takes to properly Kure the rocks varies. Thirty days is an average.

Tips and Tricks
For more tips and tricks on rock making, please read here: http://archive.reefcentral.com/forum...85#post9684885

[Yinepu]

Has anyone tried using stucco? If so... what were the results? I would think it wouldn't be as porous.. but I'm not 100% sure on that.

I'm also not sure if it would need to be handled like the portland cement mixes for kuring times or not...

[JohnL]

This thread was automatically split due to performance issues. You can find the rest of the thread here: http://archive.reefcentral.com/forum...readid=1094586