Our 55 Gallon FOWLR Experiment

**Janelle** · 07-10-2011, 05:12 PM

Thanks SMAUG! We'll have to look into getting some wire to add strength to our pieces, and see how it works.

Whilst I was on vacation for a few days, my boyfriend continued making rocks without me. He actually managed to come up with a pretty decent cave rock.

Image: Cave Rock that looks disturbingly like the Wizards Hat from the Harry Potter Movies

He's got a few more bits that are out on our patio drying in the tub of sand. Now, its time to head off to the beach for a break ... and more sand!

Meanwhile. Every time we finish a rock, we go ahead and put it in the completely empty aquarium to soak. That way, as we make more and more rock, any problematic compounds or chemicals are already leaching out of the ones we've made.

Here's what we've got so far (keep in mind some of this won't be used, and some will end up in the 40 gallon sump)

Image: 55 Gallon Aquarium with our concrete rocks thus far

**smaug** · 07-10-2011, 06:14 PM

That pile on the right looks very unstable. If just one little thing give way an inch its all very close to the glass.

**Janelle** · 07-10-2011, 08:39 PM

Oh don't worry. Its not going to stay that way. We're still not even sure which pieces will be in the show tank and which will be in the sump. They're just kind of being tossed in haphazardly at this point as we make them. We're going to arrange them a bit later.

**Cliff** · 07-10-2011, 08:50 PM

Just curious, but are you using rock salt in your mix when you make your rocks ?

I’ve read a lot of DIY info on make rocks that suggests to do that. That way when you soak the rock to leach out the chemicals from the cement, the slat dissolves away and gives your rock a more porous surface and greater surface area for BB to grow.

Just a thought

**Janelle** · 07-11-2011, 09:07 PM

We've been playing with different ideas to create porosity and surface area. We saw one suggestion to try mixing in spaghetti, but we haven't tried that. Someone else suggested rolling the balls in corn chips. The idea with both of these being that they'll dissolve out in water.

I like the idea of rock salt better, so that I'm not putting any other sources of organic materials (food) into the tank, even though we're going to completely change the water out (more than once, I'm sure) during this endeavor.

I'm going to do some research on whether or not salt affects the hardening ability of concrete, then I may give it a try!

Thanks Cliff!

**Janelle** · 08-09-2011, 07:45 PM

So, I realize its been nearly a month since the last time I added to this. The creation of "live rock" from scratch has been slow. We have a limited amount of work space where we can create the rock and allow it to set up, so we can only make a few pieces at a time. In a way, this is good - it keeps us from trying to start the tank up too quickly.

After trying several different methods for creating the rock and increasing the surface area and porosity of the rock, we've settled on mixing the concrete with a very large grain, course sand mixed with very small bits of shells. These rocks come out nice and sturdy, but with a porosity similar to pumice or lava rock.

We did some research and some trial and error and decided that once the new-made rock has completely hardened, soaking it for 24-48 hours in fresh water, then for another 24-48 hours in vinegar, then for another two weeks in salt water, the toxins leech out, and they no longer affect the water quality when they are added to a tank. We've done this already with all the rocks we've made so far, and are continuing to make more in small batches. We have about half the rock needed for our tank made so far. Most of it will be used in the sump, as many of the pieces are not particularly attractive for tank-scaping.

With practice, however, we've improved our methods and we're starting to make caves, arches, and other cool shapes for the main tank.

I knew this was going to be slow. I'll try to update with some pictures when we get some of the newer, more decorative pieces ready for the main tank.

**Cliff** · 08-09-2011, 08:18 PM

You might want to re-consider the lenght of time you are soaking your cement before it is ready to add to the tank. I once looked into making rock as well and everything I found suggested anywhere from 2 to 6 months of soaking until the rock no longer had a effect on the PH of the water. Below is one example:

http://reefcentral.com/forums/showth...highlight=rock

Just a concern.

**Janelle** · 08-09-2011, 09:11 PM

Thanks Cliff. I've been keeping a pretty close eye on the pH as we add rock to the tank, and its been very steady at around 8.2.

Maybe mine is taking less time because of the 100% vinegar soak?

I went too fast with my fresh water tanks, and only averted disaster through constant vigilance and lots of water changes, so I'm really taking my time with this tank. I'm certainly not close to actually stocking the tank yet, though - so I'll continue to monitor the water parameters closely.

**chrisfraser05** · 08-09-2011, 09:37 PM

I'd be really concerned about the porisity of the rock too.

The method using rock salt really does work.

also white concrete is recommended as it will colour up so you can't even tell the difference once its livened up, grey rock will take alot longer and will more than likely always seem dark!

**hockeyhead019** · 08-10-2011, 02:01 AM

agh not to keep beating the dead horse but making rock always scared me lol only because there's so many variables in the mix and I think that they tell you to give it so long it to allow for any toxins which you might not be able to test for are leaking out... just a thought though I've done more than scratch the surface of making rock.

Best of luck to you though! I'll be along for the ride as long as you keep the journal updated