Building hollow rock

Discussion in 'Anything DIY Related' started by Paul B, 17 May 2011.

  1. Paul B

    Paul B

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    I know there have been numerous threads on building rock, but I think I make it differently. I make it hollow so besides allowing me to make it any shape, it also helps grow anerobic bacteria that will help with nitrates.
    My entire reef structure is supported on this type of "rock" and I can build rocks very long and thin, something that is not easy to build with other methods. It is also very cheap, practically free and only takes about 15 minutes over 3 or 4 days.
    First I bend a piece of PVC pipe. "This MUST be done outside with the wind going away from you." Melted PVC fumes are toxic and will sicken you instantly. If you use a heat gun it is better as it will not char the PVC but I use a propane torch and it must be done outside. You do not want to sniff any melted PVC. Trust me.
    I play the torch over the pipe until it softens, then I bend it in odd shapes and stick it in water. You need a hose near by because sometimes it may go on fire. If you keep the torch a distance away that will not happen but keep a hose ready anyway.
    I use "Sakrete" cement.
    [​IMG]
    Then I cut the bent PVC in the shapes I want it. These smaller pieces will be used to support my reef structure when I re aquascape shortly. The larger piece will be used to support a coral.
    [​IMG]
    I attach a base of acrylic plastic. I use a stainless steel screw and thread it into the acrylic, then glue gun the head of the screw into the PVC. Some people are afraid of stainless steel so you can use nylon screws. I have holes drilled all over the PVC to facilitate water entry. When I stick the head of the screw into the PVC pipe, I just stick the glue gun into t lower hole and fill it with hot melt glue.
    String is wrapped around the PVC and secured with hot melt glue. Then cement is mixed kind of loose, this is smeared all over the string (wet the string first, the cement will stick better)
    You will get a thin coat of cement all over the thing, but you can not finish it all in one day.
    Put a bucket over it and let it set for at least two days. Then blob on more cement and wait sanother 2 days. Neatness does not count and you want the cement blobbed on rather than smoothing it on. Eventually, you will have something that will look better than any rock you can buy and coraling algae grows much better on cement than it does on real rock. Cure it in some water for a few weeks before using in your tank.
    Here I started to put cement on one piece. The shell on top will eventually hold a coral.
    [​IMG]
    This piece (before and during construction is 3' long)
    [​IMG]
    Here is another piece supporting my structure.
    [​IMG]
    This "old" bottle was also constructed using cement.
    [​IMG]
     
    DanieDJ likes this.
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  3. MistaOrange

    MistaOrange

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    Cool thanks for sharing Paul:thumbup:. I never thought about using the string but only tried using the PVC pipe but cement had no grip so the pipe would just loosen up & just abandoned the build. I'll try using the string method & get some white cement & mix it with aragonite & coraline scrapings to boost the coraline growth. Shot Paul for another great build:1:
     
  4. Paul B

    Paul B Thread Starter

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    Thanks,
    I used to use plastic screen but the string works much better, you can see one of those skinny rocks here above the copperband
    [​IMG]
    You can see the larger rock here behind the moorish Idol and all the way to the left under the torch coral.
    [​IMG]
     
  5. MistaOrange

    MistaOrange

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    Awesome & a great looking tank too!!
     
  6. amalick

    amalick

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    So cool, I think i'm gonna give this a shot for my new build.

    MistaOrange : Are you up for a joint DIY build on this seen that we are so close to one another and you seem to be more clued up than I am?

    Paul, Firstly thanks for sharing :

    1) How long does it have to cure in water before you can use it ?

    and

    2) are there any negative impacts on using string once it has been submerged. Probably a stupid question but doesnt it start to start to rot or something ?
     
  7. Paul B

    Paul B Thread Starter

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    I only cure it for 2 weeks because they are small and don't have much cement in them. I never had a problem. I built all the pieces in the first few pictures in about an hour. I will need to put more cement on them in a few days and I will take finished pictures. They grow copious amounts of coraline algae and even I can't tell in my tank which pieces are real and which I built unless I break them.
     
  8. MistaOrange

    MistaOrange

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    Sounds like a plan besides I was going to post this link on your page & hoped you would be keen. I like it :thumbup:. I already have a 6kg white cement & also have a bucket of aragonite which I scored from someone who shut his system down a while back also have some PVC pipes various sizes but could use the red PVC pipes as they were cheaper & are left overs from my flat. So we are halfway there. I just don't have the burner & string other wise all good;).
     
  9. seank

    seank

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    Very interesting way of doing it Paul, I like it very much. Thank you for sharing
     
  10. Tremayn

    Tremayn

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    Very good man! My diy rock is so brittle. Now I know how to make it strong :) .. You can also use play sand instead of aragonite... thats what I did
     
  11. robertkukla

    robertkukla

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    WOW
     
  12. predator

    predator

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    awesome
     
  13. Paul B

    Paul B Thread Starter

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    This rock is not really brittle but being the cement is thin, some of it can break off if you bend it too much. But it can be easily repaired.
    Here is my mandarin hunting on a piece of hollow rock. I don't remember when that was but it looks like I had a nice growth of algae then.
    [​IMG]

    This "old" bottle was "built" using cement. It looks to be ancient.
    [​IMG]

    I also build this "conglamorate" rock. I wrote an article of how to build this quite a few years ago. This 20" rock forms the backbone of my reef and it was built out of about 10 small discarded pieces of rock and dead corals cement together in this shape. In my reef you would not be able to pick it out as I can't even find it, but I know it is in there someplace. It blends in very well and is very strong.
    Almost all of my rocks are either built hollow or they are rocks I collected in the sea and cemented together to make them into the shapes I needed.
    [​IMG]
     
    Last edited: 18 May 2011
  14. amalick

    amalick

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    Jeez dude:blush:. I never meant you needed to supply everything. I just wanted to pick your brain while I tried this. Anyway seen that we are doing this. I have the burner, as well as string and some old guttering down pipes that we can mess up LOL. Will PM you for a get together over the weekend.
     
  15. amalick

    amalick

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    Your the MAN:yeahdude:. If I can get this right your idea is going to save me mega $$$$. And I will have some really awsome aquscaping that I would never have achived with base rock. I'm thinking TONGA branch lookalikes !!!
     
  16. Paul B

    Paul B Thread Starter

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    There is a lot of rock in my tank and I collected all of it in the sea except for the pieces I built. Almost all of my rock I modified, or incorporated it with other rocks to make larger pieces. You can't really do much with small rocks.
    But remember to heat that PVC outside and stay downwind of it. It will sicken you instantly if you breathe the fumes. Don't say I didn't warn you. Also kep a supply of water near you as it does catch fire very easily. Just try to heat it enough to bend it, then stick it in water. The stuff is practically free to build and you can make much nicer rocks then you will ever see for sale because rock like this would break in transit. It is nice to make a long snaking rock that extends the entire length of your tank.

    [​IMG]
     
  17. leslie hempel

    leslie hempel Moderator MASA Contributor

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    very interesting
     
  18. DanieDJ

    DanieDJ

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    rope it in

    I also have lots of crafted rock, this is such a good idea. Thank you.
     
  19. Donovan

    Donovan

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    Suddenly i have the urge to wip out a CC and re- Aquascape:thumbup:
     
  20. MistaOrange

    MistaOrange

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    Well the goodies are just laying around but did buy the white cement last weekend for frag plugs but I've made a stack load already so it's all cool. Shweet the weekend sounds great.

    Nice I like:thumbup:
     
  21. Paul B

    Paul B Thread Starter

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    These pieces are almost completed, now I can get creative and cement small pieces of dead coral on and make the surface lumpier. The smaller pieces will be supports for my main reef structure. I am always looking to keep the large rocks off the substrait and this is usually how I do it.

    [​IMG]
    Here is a piece that was in my tank for a decade or so
    [​IMG]
    It kind of disappears in my tank
    [​IMG]
     
    Last edited: 21 May 2011
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