# Making my own rock



## Tim (Dec 11, 2011)

Today was the first test batch. Porter cement, ground oyster shell and large water softner salt. I made 1 shelf piece and 1 goby/firefish cave. I have it covered in sand in a box on my balcony. I am going to let it set for 36 hours before pulling it out so tomorrow evening sometime.

To make sure the pieces are strong enough to have rock stacked on them in a tank I am going to stand on each piece I make and see if it collapses or not. I am 5'8" and 192 lbs so if it doesn't collapse, it should be good. 

I will try and get pics when I pull it out of the sand. I will probably let it sit out overnight and then get it into the water the day after as my RO unit is supposed to be here tonight and I can spend tomorrow getting it together. Some people seem to let their rock sit in regular tap water for a month then let it sit in RO for another week, but I figured I may as well just start it in RO from the beginning.

I was going to originally use the white porter cement but then after looking at the marco rock in my tank, it hasn't been white in a while (more grey than anything) so why bother spending the extra $$ on white when the grey is only $12.00 a bag.

I would be interested in hearing about what kind of different pieces I should try and build since my aquascaping is beyond terrible LOL.


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## J_T (Mar 25, 2011)

You are right to go straight to RO water. Tap water tds is high already. Not leaving much room to absorb anything (and you want it to soak up the salt you used) the Ro water will aggressively pull everything up. 

Having said that. The new RO unot will need to run a lot of water down the drain first to clear out and coatings, and reidue on the membrane. Dont use that water. I don't know the exact numbers off hand, but I am sure you could find it easy enough.

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## 50seven (Feb 14, 2010)

Yay!!!! Fun, fun fun! 

Can't wait to see pics!

A few pointers:

Wait at least 3 days before you stand on them, because the cement takes time to get to full bond strength, and so you might break a piece that if given more time would be a lot stronger.

I made a mock-up of my desired rockscape using Play-doh before I started anything, and it really helped me to keep the end product in mind as I played in the mud.

Maybe try to take a few smaller dried pieces and stack them up nicely using odds and ends from the recycling bin to prop them up. Then mix a small batch of cement and glue them together. Just be good and patient to wait 3 days before moving it.


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## Tim (Dec 11, 2011)

My RO unit arrived 

^%$#^$ aquasafe left a druggie sized bag open that had all the tiny parts to the faucet and they fell on the floor when I opened the box. 

Some are pretty small so I hope I found all the bits and pieces or this test may take a little longer than I expected.


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## J_T (Mar 25, 2011)

Everything in that bag is available at the HD/Lowes. 

Snap a picture, and I am sure we can point it all out, and perhaps what is missing.


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## Tim (Dec 11, 2011)

Thanks for the offer but it looks like it is all there. Found a parts pic on their site. Their instructions leave a little to be desired.


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## altcharacter (Jan 10, 2011)

It's fairly straight forward assembly actually, shouldn't be a problem putting it together since it's really just one canister going into another.

Pictures!!!!


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## Tim (Dec 11, 2011)

I am going to go to Concord tomorrow to go and look at/pick up a two way diverter valve since I can't pierce our water pipes.

J_T sent me a link to a BRS one and it looked pretty good, but I found another good one and local (concord)

http://www.maxwaterflow.com/Two-Way-Diverter-valve-14-barb-with-switch-collar_p_287.html

If I understand this one correctly, the top barb diverts water to the RO unit, and the bottom barb handles the waste water and directs it into the sink. Nifty.

They also have the same one that BRS has but on the site it says out of stock.


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## Tim (Dec 11, 2011)

Tim said:


> I am going to go to Concord tomorrow to go and look at/pick up a two way diverter valve since I can't pierce our water pipes.
> 
> http://www.maxwaterflow.com/Two-Way-Diverter-valve-14-barb-with-switch-collar_p_287.html
> If I understand this one correctly, the top barb diverts water to the RO unit, and the bottom barb handles the waste water and directs it into the sink. Nifty.


The threads didn't match to my faucet doh! Have to go back tomorrow to see what else they have.

For the rock test I did
1.25 parts cement, 3 parts oyster shell, 2 parts salt.

The shelf rock test was a failure. It broke in half while lifting it out of the sand. It was a bit crumbly too so I think I have to add a bit more cement, and cut back a bit on the salt. It looks like the salt chunks are a bit too chunky, so when they were touching they weakened the structure of the rock.

The goby cave has stayed together so I have left it out in the sun to harden. Some parts look a bit crumbly as well

One thing I wasn't sure about was how much water to add. All the youtube videos showed them being fairly tight with the water. What I did was wash the oyster shell in the mixing bucket then drained the water, added maybe 1/4 cup then mixed in the cement. Looked decently wet.


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## altcharacter (Jan 10, 2011)

with cement, the more water you use the more likely it's going to turn out to be a failure. Cement works better if you use very little water.

pictures!


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## Tim (Dec 11, 2011)

Here are some pics.

And no I didn't use a lot of water at all. I think it was the size (and too much) of the salt TBH and not quite enough cement. I have lots so I can play with the formula.

1st pic is just the 3 pieces after a quick rinse. They were covered in sand and since the shelf had broken, I figured I would clean it in tap water.

2nd pic is cave fiorst then 2 shelf pieces. Lots of salt where the concrete broke in half. Lots of salt fell out as well.

3rd pic, close up of the shelf, you can see the salt at the front edge where it broke

4th pic is the goby/firefish cave. What I did was made a pile of salt then piled the concrete around it and on top. Since the rock may sink in the sand (since it would be on the bottom) I think next time I will make the rock bigger, and the opening a bit larger to account for any sinking.

5th pic, the cave again with a more top down view so you cxan see the salt. Not as concentrated as it was in the shelf piece(s)


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## 50seven (Feb 14, 2010)

Tim said:


> The threads didn't match to my faucet doh! Have to go back tomorrow to see what else they have.
> 
> For the rock test I did
> 1.25 parts cement, 3 parts oyster shell, 2 parts salt.
> ...


Looks good so far, you're doing it right!

The mix is perfect, don't bother to add more Portland cement, it won't change much. What WILL help is to leave it in the sun for 3 days. Have fun breaking it then!  As it cures, it will increase in hardness as it turns white, and this will take at least 2-3 weeks minimum. And it will do it under water as well, just takes longer to turn white.

Your mix is perfect, just make sure you add the Portland and oyster shell first, and add as little water as possible. When you have a consistent mix (kinda sticky in a way), then add the salt, stir as little as possible to get it evely distributed, and then quickly shape it into your rocks.


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## Tim (Dec 11, 2011)

ha well that is the idea, just leave it outside for a few days then start soaking it. My next tank is probably a year away so I have lots of time. 

I still think it is the salt. Such big chunks there was little cement in some areas lol. I may break some ofthe salt up into smaller pieces and give that a try. I will wait for a couple days for this batch before doing anything else.


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## Tim (Dec 11, 2011)

The batch is in a bucket of RO water. There is a little bit crumbling, all around where the largest chunks of salt were. Next batch is going to have some smaller pieces of salt.


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## altcharacter (Jan 10, 2011)

Just my opinion, but I think you'd be alright with the larger rock salt but you might have to compact it a little bit more...but who knows i'm probably wrong


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## Tim (Dec 11, 2011)

Some of the salt was the length of my finger. 

This time I put 2/3 of the salt into a bag and whacked it with a hammer a dozen times or so to break up the bigger pieces. The other 1/3 had some large ones in it.

I also upped my ratio of portland as there was still more crumbling. Now I am up to 1.75 parts portland cement. I liked the look of this and it was closer to some of the other recipes I have seen on the net.


I only made 1 piece today but it was a bit more complex. I saw a neat fake rock in big als so I decided to try and replicate it. It reminded me of a pagoda. Think of an upsiode down U with a shelf on top and one off to one side. If the recipe adjustment works, this is a piece I will either keep or try toi improve upon.


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## mandarin (Apr 8, 2010)

Nice work... You can also use a little sand in your mixture... Make sure it is silica free (I use sand from Bomix)


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## Tim (Dec 11, 2011)

OK so a new follow up.

The "pagoda" piece turned out well. There was much less crumbling, the smaller salt pieces allowed the structure some greater strength, while it was still very porous.

Then while walking to my soaking bin I dropped it LOL. One of the shelves broke off, but in a testament to it's strength the piece didn't shatter. I decided to leave it out and let it cure for a few days before soaking it.

So overall fairly pleased. But I won't be buying the same salt next time if I can find some with smaller chunks just to save me hammering it and irking my downstairs neighbours. The brand I bought was Sifto Crystal Water Softner Salt 20 kg bag and it was between $6-$7. There were quite a few other brands at Home depot all arond the same price, so next time I will make another choice.


Now for the next experiment. This one is using Aargonite sand as I had a bag of it laying around. I decided to try and replicate my pagoda piece.

recipe:
3 oyster
1 sand
1 cement
1 salt

This time I beat up the salt a bit more, making nearly the entire batch of salt about twice the size of road salt. A few bigger pieces here and there. I am going to leave this batch in the sand for 36 hours, and then let it air cure for 3 days before soaking it and then compare it to the previous piece.


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## 50seven (Feb 14, 2010)

Moar pics!!!!!!!!!!!!!!


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## Tim (Dec 11, 2011)

Tim said:


> OK so a new follow up.
> 
> Now for the next experiment. This one is using Aargonite sand as I had a bag of it laying around. I decided to try and replicate my pagoda piece.
> 
> ...


I have to say I really like this mixture. This piece is for the future tank. I decided to leave a little of the structure above the sand to see what it did. I had a feeling that because the sand around the cement was a bit wet, it was contributing a little to the crumbling.

This batch was in the sand for 24 hours. I know I said I was going to leave it in for 36 but you know how it is 

I used a plastic beer cup to make the tunnel and piled the cement around it. The only thing I would like to see improved is the tunnel inside. It is too smooth so it looks manmade. That can easily be rectified by littering some of the bits and pieces that crumbled off previous pieces.

And as requested pics of the piece: And if you notice on the last pic, you will see a dark line. This is showing the level that was above the sand. Note how wet looking the cement is below the line. It is still solid but it is wet-ish. I won't be washing the sand off the base until it has had a chance to cure for a few days. Save the next step for the weekend. The back is flat as it was against the box containing the sand. I Intend to have it against the wall of the tank.


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## J_T (Mar 25, 2011)

I think you are getting the hang of it! I would leave the tunnel as is. Give that a couple months, and sponges, coraline, and all the other goodies will hide the smoothness.

Next thing you should consider, is frag placement. I for one hate seeing plugs. So, if I were making rock, I would make spots that the plug fit into perfectly. Then, when the coral grows, it will match the rockwork. Not a quarter sized base, then onto the rockwork!

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## Tim (Dec 11, 2011)

J_T said:


> I think you are getting the hang of it! I would leave the tunnel as is. Give that a couple months, and sponges, coraline, and all the other goodies will hide the smoothness.
> 
> Next thing you should consider, is frag placement. I for one hate seeing plugs. So, if I were making rock, I would make spots that the plug fit into perfectly. Then, when the coral grows, it will match the rockwork. Not a quarter sized base, then onto the rockwork!
> 
> Posted with my Xperia, using Tapatalk 2


Thanks. I didn't think, the hole looks smooth now but I haven't washed out the salt yet, so I doubt it will be smooth when finished.

I hate seeing plugs as well. Problem is I am not exactly sure how all this will lay out with the holes from the salt etc. What I was going to do was either trim the plugs to fit the holes like I am doing with my current tank, or once the layout was complete I ws going to drill some holes into the rock for the plugs to sit in.

I still have to learn a lot about different types of corals. I have seen some that I like, but have no idea what they are, so don't know their needs. I know they are SPS but beyond that no idea. Hopefully I get a few answers soon from a post in another thread.


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## J_T (Mar 25, 2011)

If you would like, drop me a line. I can make something up in plexi. You could stick them in the wet rock, and pop them out when dry. Then the basic plug would sit right into your rock.

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## altcharacter (Jan 10, 2011)

Tim, another idea for making holes and such is to use balloons of different sizes to get the shape you want. If you wanted a rough look to the rock you could always use packing peanuts also.


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## Tim (Dec 11, 2011)

You can use salt as well for the holes. This time I just wanted to make sure I had a decent thickness of a hole. One thing I didn't mention was I filled the cup up with sand to stop it collapsing from the weight of the cement above it.

I was watching one guy use balloons on youtube, and he filled them with water rather than blowing them up to make sure they could handle the weight. I considered using it buy didn't want to deal with popping water balloons. My kids already have enough fun 

What I do know is after countless hours of messing around with play doh to help me design some aquascaping, I have realized I suck at it. I have looked at literally hundreds of tanks. Rather than try and design, then make, I am just going to make a bunch of different shapes and shelves, lots of smaller pieces and then start stacking and figure it out as I go along.


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## 50seven (Feb 14, 2010)

Oh boy, that looks like so much fun!!!!!!!!

Makes me want to start another tank


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## Tim (Dec 11, 2011)

Ha well it looks like I am going to have tons of cement left over!

I will probably use up as much of it as I can and will trade some finished pieces for frags for my next tank  Make up for the set of RO filters I am going to burn through lol.

I bet I will still have tons of cement left after all that.


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