Building hollow rock

[Paul B]

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.

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.

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.

This piece (before and during construction is 3' long)

Here is another piece supporting my structure.

This "old" bottle was also constructed using cement.

 

[Markee]

Thats really cool! They look so real!

 

[Paul B]

Thanks, you can see one of those skinny rocks here above the copperband

You can see the larger rock here behind the moorish Idol and all the way to the left under the torch coral.

 

[Markee]

Your tank is beautiful! That rock is awesome!

 

[Paul B]

Thanks, I keep trying :yo:

 

[Paul B]

These pieces are almost completed. Now I can get creative and cement pieces of dead corals and put on some rougher, finishing touches.

 

[Markee]

Very nice. Going to look awesome in the tank!

 

[10gnano]

Nice start, should turn out pretty nice for you. I tried making agrocrete stuff awhile back and didn't like how it turned out, this idea looks a lot better.

 

[Paul B]

Here is a piece that was in my tank for a decade or so

It kind of disappears in my tank

 

[Mr. Limpid]

You have inspired me. Wanting to do a long bridge but haven’t found the right rock, now I can make it. Have never read the ingredients in sakrete will it dissolve or leach into salt water?
Also you have a Moorish Idol how long have you had it? Always wanted one heard to many horror stories about them.

 

[Paul B]

Have never read the ingredients in sakrete will it dissolve or leach into salt water?

Sakrete is cement, it will not disolve and will last as long as the pyramids. I have some in my tank for decades, no problem.
That moorish Idol I had for almost 5 years died with many of my other fish in an accident. That post you read it on was a few years old. My tank now is too full to get another Idol but I really like them and believe I now know their secrets and can keep them. I had to go to Tahiti and spend time with them to try to figure it out

 

[Mr. Limpid]

5 years is a great job I have a falcula butterfly that has just past the 5 year mark, he is the solo survivor from an ick attach. I learned the hard way that ick can come from anything; I placed LR directly into my tank. I would like to know the secrets on how to keep them alive or do you have to kill me after you tell me LOL. I was always told that they were one of those fish best left in the ocean.

 

[Paul B]

I was always told that they were one of those fish best left in the ocean.

They probably should be.
I have found by swimming with them that they eat a lime green sponge all day. I found a sponge growing here in NY that they also love and it freezes well. I could collect anough in a half hour to last all year.
I would feed that along with pellets soaked in fish oil. The pellets would be automatically dropped into a dish in the tank every few hours and the Idol learned to check the dish all day. They are a pain to keep but the most beautiful fish and not very rare at all. They are all over the place in the South Pacific.

 

[Mr. Limpid]

well I think you found a new product to put on the market, I know of alot of people that would buy your food so they could keep a Idol. I would be your first customer, I'm in Illinois not near an ocean.

 

[Paul B]

The stuff is fairly common here in NY but it is only found on floating docks near the surface. It only grows right near the surface so it is not found on the bottom or on rocks because our tide goes up 8'.
It freezes well but must be frozen with in a few hours of collecting or it rots.