DIY liverock.

A great guide I found while looking into the DIY LR, Mixing rock salt helps make it a lot more porous. Just thought I would share.

I don't have a Link to the original post I copied this to word a while ago, sorry.


By Insane Reefer -
v9.0 FINAL VERSION: Aug - 14 - 2008
Hey All,
These are my favorite tips and links 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, though I learned about it from the pre-internet BBS's back in the very early 90's. Lately, I have even made some money on my rocks.
THIS WILL BE MY LAST MLR POST

This does not contain any information on "Jiffy Rock", the new method I am working on to produce rock in under a week or 10 days. This only pertains to traditional rock methods.
I thought I’d pass this info on – maybe save someone some frustration or spark a new idea.

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

List of Appropriate Aggregates
Sand - Sand makes cement stronger, so is something you want to add to your cement. You may also find that sand is a great casting medium and that you can get crazy shapes with damp sand. Any “clean” sand will work – look for darker grains which could indicate heavy metals and avoid these sands. Whatever you choose, keep in mind that the smaller the grain size, the less obvious it is on the rock, but for sand for use in the cement, you want a larger particle size, if possible.
Caribbean/aragonite is “best” for adding to the mud, but very hard to find at a reasonable price.
Play Sand is generally fine to use - most play sands will be made of quartz and so basically inert.
Limestone Sand/Pulverized Limestone has gotten good results as a DSB, so should also work and can be found at some Big Box Stores like select Home Despot's.
Glass Sand is a new product on the market that is made from recycled glass - this would also be an excellent choice and might encourage quicker coralline growth.
Calcium Carbonate for “Feed Mixing” (AKA Aglime, Chicken Grit, Scratch Sand), comes in a range of textures and grain size – from sand to gravel like CC. Most real feed or farm supply stores will carry it in some form, and for less than $4/ #50, but make sure it is the calcium based stuff and not granite based – it should have a percentage of calcium printed on the bag – if not, it might not be the stuff you are looking for.
Dolomite Sand – Same as Calcium Carbonate, just another name (and slight chemical variation) and is just fine to use - you might find it as "Aglime" at the farm supply store.
Sand Blasting Sand can also be used (and works really well as casting sand) and is sugar fine, look for "Unimin" Brand, or any that says it can be used for filtration – this will be 99% pure Industrial Quartz.
Crushed Coral - AKA "CC". Makes nice, realistic rock with a high over-all calcium content, but it is expensive.
Crushed Oyster Shell - AKA "OS". Any shell will work, but OS is very cheap at feed stores.
Perlite – has a pore structure similar to CC, but much, much cheaper – great for making light weight rock. It is basically inert, puffed glass. Make sure that the perlite you choose does not have any fertilizers added to it – most do not, but a couple do.
Salt - Many thanks to Travis L. 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. Look at your grocery stores or wally-worlds if your local hardware doesn't have what you want.

Rock Recipes
Ingredients are measured by volume, not weight!
Travis’ Original “Salt Rock” Recipe: 4:1 or 3:1 / Salt:Cement
Improved? “Salt Rock” Recipe: 3:1 or 2:1 / Salt:Cement
Ol' Skool Recipe: 1 to 1.5 : 2 :1 / Cement:CC&OS(mixed – or use perlite&shell mix):Sand
Ol' Skool + Recipe: 1: 1 to 1.5 : 1.5 :1 / Salt:Cement:CC&OS(mixed – or use perlite):Sand
I prefer the "Ol Skool" recipe, but I use a variation with perlite. Makes excellent, porous rock. Keep in mind that even though the original “Salt Rock” recipes do not have sand listed, your rock will be much stronger if you replace a portion of the salt with some sand. On the “Original” recipe I’d use 2 sand and 2 salt to 1 cement.
It is highly recommended that you do not make “Salt Rock”. Salt is horrible for cement, and over the last 6 months, I’ve had more and more complaints coming in about failed, crumbling rock, and guess who gets the blame? Even the “inventor” of Salt Rock, Travis L. Stevens has written and said he too, has salt rock breaking up. So my advice, if you want stable rock, is to not use salt in it, or if you just have to even knowing it is bad, then use it sparingly.
Basic Procedure
Mix dry ingredients together first, excepting salt if used - add tiny amounts of water while vigorously mixing the mud. Mud should be sort of “dry” and a little bit crumbly, not wet and squishy – there is a fine line between the two. A wet mix will not have as many natural voids in it, be less porous, and will also bind to the salt, making salt release more difficult.
If you aren't adding salt, skip this next part.
Once you have reached a slightly wetter mix then you think you need, lightly toss the salt into the mixture, and then mix it very quickly – the more salt that leeches off the crystals, the more deleterious the results can be, meaning more chances for your rock to be messed up.
Be aware that a "dry mix" may give the illusion for the first week of being more brittle, but after a week or two, it toughens up and is nice and hard.
As you cast your rocks, try to "drool" the mud into place with marble sized drops. This prevents large solid masses from forming and makes lots of natural channels within the rock that will allow water to flow through the rock and seems to allow the rock to kure faster. If you are making larger pieces, you can scale your "marble" size up some, but still work at drooling the mud into place.
After you make your rocks, they need to be kept moist and warm for at least a week or two to achieve the best hydration possible – though 3-4 weeks is best. Many do take their rock out immediately and start salt release or kuring in 3 days or so, and haven’t reported any bad side effects, so it is up to you. However, new info is starting to show that to put your cement in water before the 2 or 3 weeks of age is needless, as kuring doesn’t really get going until the hydration is starting to come to a halt (there has to be calcium hydroxide for us to leech it, and C-S-H is something that forms latter in the hydration cycle). It is also starting to sound like those who put their rock into the kure bin too quickly end up with prolonged kure time, so that is something to think about too. So you can save yourself some effort and money (water cost money) by letting it sit for a while to let the chemical process in the cement have a chance at finishing doing what they are doing. Plastic bags, wet newspaper, wet casting materials and the like will help seal in moisture. If you think the rock might dry too quickly, mist it with a bottle or hose every so often.
Molding/Casting Material
Really, pretty much anything that is dry and crumbly/powdery 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/casting material will remain on the rocks - most of this can usually be removed with a very quick dip in a dilute acid solution, followed by a good scrubbing with a plastic or fine wire, bristle brush.
If you use a Rubbermaid type tote/bin, you can easily 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.
Salt gives a nice dimpled effect on the surface of the rock, but can wick out the moisture from the rock, making it dry out too quickly. You can recover and reuse any salt left over, but will notice a significant lessening of the amount of leftover salt after each casting.
Sand is my casting material of choice. You can really make some nice, layered rock with sand. Once dampened, it will continue to keep your rock moist during the hydration phase. You loose very little from the casting bin, and if you rinse your rock in a tub, you can reclaim most of what you use.

Coloring Your Cement
There is a lot of interest in creating faux coralline to make the rock more interesting while we wait for real coralline and corals to dominate. First let me say that over all, I have not had a lot of luck with using non-cement colorants. I’ve tried a gamut of stuff from RIT dye and hobby paint to Kool-aid, and none of these work. Oh, for the first couple of days, they might look great, but as the kure progresses, and as calcium carbonate forms, the colors fade out and eventually can barely be distinguished. By the time these rocks are ready for the tank, the color is mostly gone. There has been success using colorants made for cement and grout, but again, these still do fade because of what we are doing to our rock.
Having said that, I have some other things to say for those still wanting to try it. Use real cement colorants – I have a couple of sources listed below.
Sold in small amounts and in rainbow colors - are very cheap and most should be reef safe as well as mostly color fast:
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http://stores.ebay.com/BEACHCRAFTER...QQfsubZ16QQtZkm
http://stores.ebay.com/Olde-World-C...4QQftidZ2QQtZkm
When you are coloring portland cement, make the color several shades darker than what you are hoping to end up with. You can choose to color the mud itself when you make the rock (as Walt Smiths' rock company does), but you will need a lot of colorant to do so, especially in grey cement. Instead, you can make up a slurry of cement and sand to make a "paint" of sorts. Use 1 part cement to 2 or 3 parts really fine sand, made fairly thin and fairly wet and sloppy (like house paint), and use it to decorate rock with “coralline algae” splotches. I’ve used white Portland, but I don’t see why white grout or mortar wouldn’t work as well – you can use grey, but grey needs a lot more colorant to reach a desired shade. 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.
I’ve been thinking about how the colors fade and think I might have a solution. Fast set cement. With it not really needing to kure, you could make your “paint” from the fast set, and the best part is that being impermeable, it should fade very little (fast sets carbonate very little from what I’ve read). This would be something you could add to the rock after it has been kured. Then maybe soak it for a few days after the “coralline” has cured (2-3 days for fast sets).

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Now, I will list my tips and tricks, in no particular order.
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. Fast Set cements can be used, and are in fact great for things like panels or delicate branchwork, but because of their naturally impervious nature, are not the best choice for filtration rock.
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. 1 part cement to 3-4 parts “other” is an acceptable ratio, whatever you want to mix together is up to you and you should be ok if you follow the 1:3-4 part rule - each person usually finds a recipe on their own that works best for them.
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 very 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 might 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. 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.
14. 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.
15. 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 the rest of the 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. See my gallery for pictures of the “”Reef Face” or “Nessy”.
16. 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.
17. 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 and heavy. 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, 7 days being much better. 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.
18. 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.
19. 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 to four weeks before starting to water kure, it will dramatically speed the kure time.
20. Dust your molding sand with oat flour for easy removal of surface sand. Thanks Rhody!
21. Mix molasses with your molding sand to give it more texture. Thanks Rhody!
22. Replace up to 1/3 of your cement with “Hydrated Lime” – this reduces the over-all alumina content of the cement (and boosts the calcium content) and makes it more resistant to potential “Sulphate Attack”.

 

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