Manmade Rocks HowTo & Tips(aragocrete)

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Manmade Rocks HowTo & Tips(aragocrete)

Post by DAMIAN » Fri Dec 08, 2006 8:51 am

This will be a brief outline on how to mix and create basic Aragocrete/Concrete rocks. Below this will also be some additional tips and how to's.
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Step One
Thorouly mix all of your dry mix, when you think their mixed good enough mix them another few minutes. Theres never too much mixing of the dry products, it helps to ensure good even mixture of all ingrediants.

Step Two
Very slowly add your water to the mix(for our ten pound bags start with about 12 to 14 ounces) thorouly mixing till their is no soupy water standing.(at this point your mix will still be very dry) then very very slowly add more water very very little at a time.(its very surpriseing on your first use how quick the mix meets its saturation point and then becomes too soupy) Grab a little mix in your hand and squeeze it, if it holds its shape without oozing out or showing cracks then your ready to go. If it has cracks in the lump you squeezed then add just a tad bit more water.(always set aside a little of your dry mix incase you get it too wet you can add more dry mix to thicken it up). If you get it a little too wet then add some of the saved dry mix. You want a finished consistency lookiing similar to a thick oatmeal. Just wet enough to saturate all parts but not so wet as to not hold a shape.
Step Three
Create your molds in damp sand. Put your sand youve acquired for your molds into large containers(we use rubbermaid boxes) add enough water to the sand that its just damp enough that when you create molds(shapes) in it, that it will hold that shape for you to add your aragocrete mix into. (its a good idea to set aside some dry sand also for adding on top of your mold and or for making crevices in your design). Once you have a designe your happy with start adding your aragocrete mix to it by slowly dropping small handfulls into it from approximately 3" to 6".
Some Helpfull Tips
If your going to be making some thin shapes or branchy type pieces try only filling your mold half full at first and then mash it with your fingers to firm up the mixture(this will give it a wet looking appearance but will make it stronger finished piece) then slowly drop some small lumps of mixture on top of that to give it the finished look you want.

Try using a piece of plywood and put your mix on that to create some nice branch looking pieces that will have a flat back to them so you can put them directly against your back glass to give some depth and definition to your tank.

When making cave type pieces drop a large handfull on bottom of mold then mash it nice and flat with your hand, youll want the bottom to be as thin as possible. Then with a small stick poke a few holes into the bottom. Then slowly using your fingers add some small amounts around the perimeter of the bottom to start your cave walls. At this point add some of your sand to the top of the base piece inside the little perimeters you just made and add it to what ever height you want your cave to end up being. Now slowly drop some small plops of mix around the sand you just added and on top of your perimeter walls you made untill you reach the desired height you want and come across the top of your sand pile to complete the top of the cave.( if your going to use the cave on the bottom of your tank setup to add more rocks on top of then you need to make your cave walls pretty thick like app. 3/4" to 1"). Let your cave sit for approximately 6 to 8 hours then come back with a small stick and create some small holes in your cave walls(or use straws) so you can get some water circulation even thru your cave.

If your making arches try making varying sized arch molds into your sand mold box and dropping the mix from varying heights to give some nice unique appearances to your rocks.
Remember to look more natural every single rock will be different so if your mix spills over the side of the mold or doesnt fall exactly where you want it, it may still turn out very nice. Some of our best rocks came from designes we though were silly looking but once cured looked very nice.(remember to look more natural you need to create things that look very odd and different) If you wanted them all to look the same you would have bought plastic and not be making your own.

If in cold areas where temps dont get above 50degrees for most of the day, and your making your rocks outside you may need to purchase a cold weather curing agent from places like lowes or homedepot. You need this to ensure your mix doesnt dry out too prematurely and cause cracks and weakspots. The entire cement cureing process needs warmth and moisture to cure correctly.(if making your pieces indoors you should be fine)

Basic cureing process-- you need to keep your rocks moist for the first 48hours. Some people use spray bottles to mist their rocks with, some use a garden sprayer, what we use since were outdoors is a spray mister that hooks to a standard garden hose. We hood this up and run it after the rocks have been in molds for 12 to 16 hours and let it run for the next 24 to 36 hours. The key thing is just keeping your rocks very moist(not saturated wet) for the first 24 hours.

These are some common errors and issues people have when making aragocrete rocks and also some helpfull hints and tips.

1)--To keep from your rocks being very fragile when dried do not get mixture too soupy. If you do you need to add equal amounts of portland and sand to mixture to thicken it up. The mixture should look like its just slightly wet, and holds its shape when you squish it in your hand. If its too wet, youll see a shiney wet look to the rock. It should almost look like its on the verge of being dry.

2)--If making your aragocrete rocks with a lot of large items like crushed coral or oyster shells, then double the amount of portland used and make sure and premix all the items dry before you add water.

3)--You must use portland type 3=FALSE- type 3 portland is only for use in extreme cold areas. It is a fast setting high strength yeld portland used in areas where temprature is below 50 degrees F. If your making your rocks indoors or in the warmer climates you definitly need to use and can use portland #1 or #2. It doesnt matter if its gray or white style, they both end up with same results. However if your going to be adding a little colors to your rocks we reccomend the white to help.(grey portland give a very dark, dark grey appearance in water)
NOTE: During the winter months if your not making your rocks indoors, and your temprature stays below 50 degrees for a majority of the days youll need to get a cureing additive for use in cold weather to keep your rocks from cracking and to allow them to cure properly.

4)--Need to cure some small pieces- put them in your toilets tank, that way they get a fresh water change every time you flush. Will almost cut your cure time in half.

5)--CUREING TIMES--while this is a subject that will always be different the times we quote will always be approximates. You need to test your rocks pH before adding to your tanks.
A-----If you happen to live near the ocean or a large river you can put your rocks in for about 4 weeks(sometimes sooner but not reccomended). When you pull your rocks make sure and do a ph test and ensure the ph is reading below 8.4
Luckily we live on the Gulf of Mexico so this is our choice and have never had any problems.(except occasionally remembering where we put the last batch at)
WARNINGDo not put aragocrete rocks or any cement based rocks into a small stream, creek, or small pond, because you will create biological kills and reak havoc on the ph and other chemical elements in these small bodies of water. If you choose to use natural bodies of water make sure they are large enough to disperse any chemical alterations without adverse affects of local marine fauna including fish,inverts, plants, sediments and even birds and other animals that use that water source!!!!!!
B-----Pool or tub in your backyard- This way takes longer dependant on how often you change the water. But generally speaking approximately 6 weeks. This could be shortend by changing the water daily, or every other day.
You also need to put a circulation pump in if using a pool or rather large container.
C----- Bucket(indoors)- this way will take the longest for sure- approximatly 8 weeks. If you change the water our daily or every other day you could shorten this time dramatically.
D-----Toilet Tank Method- great for those smaller pieces of aragocrete. Approximatly 3weeks dependant on flushing amount.-put your smaller peices in the toilet tank, and each time you flush you get a fresh water change.
E-----Everyones water is different depending on where you live. Carbonate hardness, chlorine content, ph level, these are all determined by where you get your water, wether its a well or with the local city system. So dont stress out if yours dont cure in exact same time as someone else's did, everyone will always have variations. Look at it like this, unless you lived in a Lab, no two batches will ever be alike.

Always do a ph test before adding your rocks to any tank with live animals in it.
We do ours by having a vat of water with predetermined ph and then adding the rock, let it sit for 24 hours, then slowly with your hand stir the water in the vat and do a ph test. If you see little to no change then your set to go.

If you use a lot of crushed coral or oyster shells along with your aragonite sand you should end up with a ph level between 8.0 to 8.3

ALWAYS allow your rocks to cure in the mold for at least 48 hours before moving!!!

If your sand that is being used for a mold is damp all the way thru, then you should not need to do any misting or additional water sprinkeling to your rocks. The simple moister within your sand mold will provide plenty of moisture for your aragocrete to cure. If in doubt about moisture of sand, after your aragocrete has been sitting for 24 hours you can MIST some water on it, do not use sprinkler or garden hose...your almost guaranteed to get too much water in your rocks wich would make them brittle.

WEAK AREAS in a rock design----- try adding some stiffner material to your design. Embed some plastic strips into your design if your concerned about weak spots or places in your design. Kind of like adding midget rebar to a cement slab. We use plastic coated floral wires for our larger pieces that need a little internal support. Great for when you have larger branch style pieces, or long arch's or high caves. Simply put half of the aragocrete in mold, lay in your plastic stips, then lay more aragocrete on top. ( to get an even stronger hold use aragocrete sparingly at first around plastic strips and firmly mash the aragocrete mix tightly around the strips, then add more loose aragocrete on top of that to maintain your natural look.)

FLAT PIECES----- if your going to be making flat pieces for example for a shelf or backglass, end glass, or even the bottom of your tank, try using "floral foam". It has to be the undied white version. Now this is the hard white foam stuff and you can get it in sheets usually 1"x11"x36" for like $5 at WalMart..., DO NOT use the softish spongie green stuff made to hold a lot of water for plants.

·Items to create voids, gaps, holes.....
These are just a few of the items that we have physically tried and or currently do still use for making rocks with. Some of these help to make the rock have more voids and more surface area, some are completely miserable. But heres the list none the less.........Most of these items go into your mix once its all ready to use as a last step, meaning once you get the consistency you need or want with your aragocrete mix, then at the last minute add your additional items like below....

Hard Candies... try breaking these up into various sizes and pieces and they make great items to add into your mix for creating voids and such. Add this in your mix once all other items are completely mixed,(put candy in last) then make your shapes as usual, when you put your cured pieces into your water for cureing the candy will simply melt out. Works pretty good as long as your not doing real thin or branchy styled rocks. Downfall is rock candy or hard candies are a little expensive for throwing in rocks.

Rock Salt........ works great as long as its used sparingly.........(if going in a reef ensure its not iodide inclusive). Ok Rock Salt is an awesome material for creating voids in manmade rocks.......if used correctly. The ratio that we have found to be best is around 16oz. of rock salt to 10lbs of mix. Once again, do not add the salt untill just before your ready to add your mix to the molds or else youll have melted salt in your mix before your ready to use it. (we do not reccommend water softner salt-because some,not all, use chlorine as an additive-we reccommend food grade rock salt similar for use in icecream makers etc...
Another precaution with using rock salt is, BE VERY VERY sure you do not try to move the rock or even slide it or tweak it for the full 48 hours, the salt being added to the mix has a tendency to make weak spots untill the cement has hardened considerably. We reccommend leaving rocks utilizing rock salt in the molds for 36 hours. Simple put your rocks in your water to cure as normal and the salt will dissolve out......SALT WORKS GREAT-BUT DONT PLAN ON USEING THESE TYPES OF PIECES TO CARRY THE LOAD OF OTHER ROCKS---DECORATIVE PIECES ONLY!!!!

RICE---Dont use it unless you preboil it to allow for the swelling, then only use it if you have several months to let it cure out and plenty of time to allow the excess rice to either be eaten out or dissolved away. Could take many many months for internally buried pieces. Therefore unless you have time and much patience we dont reccommend this method. The upside is, this method creates some of the most porous and seems to the the most adaptive and best grade of rocks that weve every created. The rocks are awesome, the possible side effects if not cleaned properly are not worth it though.

Pasta----- Works great just be prepared to wait a really long time for the pasta in the internal area's to be able to dissolve away. If you put these into your tank prematurely before the pasta is gone completely it could leech starches into your system. Other than that pasta can really make for some unique and genuinely kickass rocks. Try different types, shapes, sizes... pita, spagettie, macaroni, twists, etc.... NOTE-- if your rocks are porous enough once dried good, you can put them in or near a large ant bed to help clean out the excess noodles. You can also use the noodle just for pressing on the outside edges of the rocks for some unique texture and design on your rocks, ( like the pasta shells, make tube worm looking holes and impressions, etc.....)

Styrofoam Peanuts(cornstarch type)--These can really create some extremely unique and dime to quarter size holes thruout your rocks. Best of all it completely dissolves away in water and its non-toxic as well. Try putting several of these whole pieces thruout the mix as your putting it in your mold to create nice void areas.(caution not to put it in a narrow or small section as to make it too week). Dont add these to your mix because they will dissolve away before you get any use out of them, rather, place them thruout the design as your actually adding the mix into the mold. We use a lot of these since their bio-degradeable and dissolve readily in water. Be experimental!

StyroFoam BB's-- (like what comes in beanbag chairs etc...) These are great to add a couple of cups of them to your dry mix and mix, mix, mix, very well. This will really give you some lightweight rocks. Only downfall is it also makes them a little bit weaker and or brittle, so this is only a good idea for more decorative pieces and definitly not for pieces that will be on bottom.

Paper Towel Cores-- (the cardboard tube from paper towels or toilet paper) These are great if you need to create a tall leg for a piece to work as a form, but are even better to create a tunnel effect or a cave mold. Once used just toss them.

Sticks/Wood-- (make sure its aquarium safe first)This is a really unique way of customising a few rocks. Make your rock around a piece of driftwood, or insert driftwood or sticks into your rock design with pieces protruding. Great for cichlid tanks. We even had one made for a customer that used a huge 3' x 3' piece of driftwood, we made the rock around the center bottom of it, with multiple large branches coming out both sides of the rock. Turned out really unique.

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