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To save some money on my next sw build, I've decided to make a lot of "aquaculture" live rock. I'll ten buy a few nice coralline covered pieces to seed the rock. This should really minimize the cost of set up because I already have lighting fixtures and ballasts, wood for a stand, powerheads, and a lot of other stuff necessary for a tank. These are the costs I paid, not the website costs:

94lbs Cement: 10.25
100lbs Playsand: 2 X 3.55
Salt crystals: 4.73
15 lbs aragonite: 16.10
40 lbs CC: 25.89

That should be $64.07. It should make 250 lbs of rock under perfect conditions. So theoretically I'm paying about 26 cents per pound. Now I'm sure I'll mess some up and lose some here and there, but I'll get a good price even if I mess up and lose half of it.

So I started today,

my work station:



The first "rocks":



I used one part cement, two parts sand, half part aragonite, one part crushed coral, and half part rock salt. For a total of 1:4 cement: other ratio. I made sure to only add enough water so that it was like mud, gloppy not runny. I lined my 25 gallon mixing tray and box in plastic before I got to work, put some sand in the box, and made two different shapes. I had to wet the sand pretty well to make any shape with it, and the plastic lined box should keep the moisture in. That coupled with the 80-90 degree averages here should hopefully cure the rock pretty well.

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Critical Fertilator: The Micromanager of Macronutrients

Glad to see you're still Mr DIY Matty. I think your last SW was bare bottom (eg no sand) but you had rock & corals. Are you doing the same again this time?

Cheers
TW

Lol, Thanks for the response Robyn!

I'm going to set up more of a coral frag system than a true display tank. This time I'll go with a little sand. I think in moderate amounts (<1" it can have great benefits. I'll use a 40g tub that I bought at tractor supply for a sump and a couple of the 25g mix trays (seen in the picture) for a system. I just need one more of the mix trays, tractor supply seems to run out of them often.

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Critical Fertilator: The Micromanager of Macronutrients

'Fake' live rock works surprisingly well, Matt... I think you'll be happy with it. My local reef club got together and made about 500lbs of 'fake' live rock in the same way that you did, and it turned out rather well. I bought about 10lb from the club and put it in my 20 gal with another 20lb of real LR... I honestly don't know which pieces are which anymore... the fake stuff looks so real after it gets covered in living 'stuff'...

The biggest problems that they had were with getting the stuff to the right density. Some pieces ended up so light that they actually floated, and some pieces were so heavy that they were barely porous.

Most of the rock that was made was intentionally made with flat bottoms so that they'd be good pieces to use for a base in rockwork... that worked rather well. They also 'got creative' and made big rock structures with glass bottles stuck in it... after it cured, they broke the bottles and took the glass out and had nice little caves... I think most of those pieces went into cichlid tanks...

Have fun with it, and good luck!

Thanks for the reply, it's good to hear the stuff ends up looking natural. As of now, the rock is still quite dark. Moreso than any natural rock I've seen, but I guess that won't be noticeable with life on it.

I surely hope mine sink but I did try to make them as porous as possible without compromising the structure. I'll get a feel using these first two rocks, and try to adjust after that.

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Critical Fertilator: The Micromanager of Macronutrients

Yeah, it'll look rather dark until it gets covered in life. I should take some pics of my flat-bottomed pieces for you when I re-scape my tank... those will probably be the only pieces I'll be able to identify as fake o.O

Some other people in my reef club used mostly fake rock and only about 25% real LR... just enough to seed the fake stuff. At first, it looked really weird... but over the months it started to look more and more normal... now it looks totally real...

And it looks like yours will probably sink. Most of the floating problems were in more round-ish pieces... you've got some deep holes in yours, so air should be able to get out of it, even if it is less dense than the water as-is...

Some other people in my reef club used mostly fake rock and only about 25% real LR... just enough to seed the fake stuff. At first, it looked really weird... but over the months it started to look more and more normal... now it looks totally real...

Hmm, wasn't even sure I'd use that much real LR. Mostly just some rubble with nice coralline on it and a small piece or two for some critters. I was thinking of not buying any at all and getting my coralline and critters from the coral frags that I bought. Dunno how well that would work though.

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Critical Fertilator: The Micromanager of Macronutrients

You could probably get away with using a little rubble and/or a few pieces if you use live sand or something, too. Otherwise it's gonna take forever to cycle the tank... and you're going to want diverse bacteria anyway.

If you're going to go with just a few pieces of real LR, I'd set up the tank, do all the rockwork/scaping, throw in a few fish, and let the tank run it's course for a good 6 months to a year. Maybe dose it with purple up a few times a week or something to help with the coraline.

Even the people in my reef club who used ~25% real LR still let their tanks cycle for much longer than normal... I don't recall how long, but it was a long time...

Yeah, I realize I'd have to take more time than normal to set the tank up with just a little LR or rubble to start the seeding. I'm pretty intent on doing this cheaply though lol.

Anyhow, I've done quite a few more rocks. The first two came out really dense, but I got the technique down, both for mixing and for putting it into the mold. Seems to become much more porous if the LR is a bit dry and you "crumble" it into the mold.

Some of the newer rocks:







All of these are now sitting in my 40g tub with just a bit of water in the bottom to create a moist environment. It's supposed to increase the strength of the rock if it doesn't go straight into water to cure.

Here's a couple shots of the first two rocks made in the tub:

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Critical Fertilator: The Micromanager of Macronutrients

I also went to a feed store and bought 4 50# bags of crushed oyster shell for $9 each. This will be used in addition to everything else. I've now used up almost all the crushed coral and aragonite that I bought and all the playsand. Most of the playsand has been used for making molds though. I still have a TON of cement, crushed oyster, and salt crystals so I'll have to buy some more of the aragonite, crushed coral, and playsand.

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Critical Fertilator: The Micromanager of Macronutrients

got some more ingredients and have made some more rock. I'm guessing I've made about 100lbs total so far.

Here are some pictures from the latest batch to come out of the molds:

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Critical Fertilator: The Micromanager of Macronutrients

Looks like you're getting a system worked out, and the rocks look good

How much time/money have you spent on the project so far? Now that you're getting the hang of this, do you think it's easier/cheaper than real live rock?

Matty ive been wondering about this for a while, is it really worth it? I mean factor in not just the cost and YOUR time donig it, but when finished it certainly isnt going to be "live" is it, it will need sumping or seeding with other (large amounts for a long time) rock, right?
Also compare this to a box of imported rock at trade price, i bet its more expensive? ie you could order a box of rock for yourself sell what you dont need and probably even make money on it..you'll be painting coraline on it next!!
Have you seen the "fake live rock" that is in the UK? Its fibre glass and only just cheaper than LR, although now i know the price of LR at trade i certainly will be importing my own next time..

I'm glad you guys just asked me all this, cause I just spent a few minutes working it all out.

I've been job hunting and haven't really found anything full time. My 30hr/week job at fintastic, the fish store down here, leaves me with plenty of extra time to job hunt AND play with rocks. I'm not really going to factor that into my "costs".

That said, I will give you a time per lb estimate. I've started to get the hang of it as you said waffle , so these should be pretty accurate for any rock making down the line. Yesterday I worked from 3:30 until about 5:45 effectively "making" in my estimation 40lbs of rock. This involved taking out 35lbs of rock I made last week from the molds they were in, rigorously brushing them off, weighing them, and placing them in my tub. I then reset the molds and made new shapes. Then I mixed the cement and put it in the molds and cleaned up. My 40lb estimation comes from the fact that I used more raw material than last week, maybe 5 lbs worth. So 40 lbs of rock in 2.25hrs or 135min. 17.8lb/hr or 3.38 min/lb.

That was a kind of leisurely pace with "beverage" breaks and whatnot.

So to the actual costs. I've bought the following now;

200lbs oyster shell @ 35.96
300lbs playsand @ 21.30
94lbs portland cement @ 10.25
40lbs salt crystal @ 4.73
45lbs crushed coral @ 24.03
45lbs aragonite @ 32.09

$128.36/684lbs = $0.19/lb rounded up. If you want to figure in what my time is worth, I make a killing at the fish store, about $8/hr. That's $0.19/lb + ($8.00/hr)/(17.8lb/hr) = $0.64/lb rounded up, before taxes.

If you can find a place that sells honest to goodness LR for less than my price, I'll quit this nonsense and buy that. I say less than my price because my rock is (IMO of course) better quality than any rock I've laid my hands on. It's way more porous and I guarantee there won't be any aptasia, fire worms, mantis shrimp (though I guess that's a negative for you mez lol!), or other nasty hitchhiker. I'll get all the good hitchhikers I want from work, and I can be really selective about it.

I'll let you know how long it takes to actually cure/kure the stuff. That will be a factor for some people. I start that next week. I imagine that it will take a month for it to stop raising the pH and another month to seed it. If you are buying boxes direct from the source, expect there to be some NASTY die off. That will take a month to cure and more to "cook", so I'm not sure that there will be much difference in time between mine and an imported box. That's why it costs so much at the lfs.

To answer your question, I think it's worth it to save hundreds of dollars. I'll at least break even, and maybe make some money selling what I get from my extra materials.

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Critical Fertilator: The Micromanager of Macronutrients

Next you will be setting up a little business on the side, selling your DIY live rock on ebay

Cheers
TW

That's not too shabby of a price for rock! I'd personally give it more than a month to seed, but whatever floats your boat.

The other cool thing about making your own rock is that you can get whatever shapes you need (flat-bottomed pieces for the bottom, then design your scape from there on up)...

How much rock do you have done so far?

The thought had crossed my mind robyn . Don't know If I'll try that or not. I guess it kinda depends if the store I work at wants any of it.

Waffle-I'm not much interested in keeping fish. I'll probably only use fish that do some kind of work for me, like control pests or eat algae. So the bioload won't be high for the tank. I certainly won't sacrifice stability in the tank for a shorter seed time. I just assume that after a month it will have gotten the bacteria necessary for use and will continue to mature while I start using the tank. I dunno, but I'll be careful and test for everything.

I have made a really nice table-shaped piece that all the other rock will rest on in the sump. That will allow flow around and under it, so there will be less detritus hopefully. I've made mostly roundish shapes with holes or caves, cause they are easy and nice to look at too. Overall, I think I've made more than 100lbs, maybe 120ish, which was the target for my prop setup. Should have a capacity of less than 100 gallons, probably more like 80 so that should be plenty of rock.

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Critical Fertilator: The Micromanager of Macronutrients

So not many fish, but lots of coral? I know that with your coral keeping skill, it will be a beautiful tank.

Like poisonwaffle says, whatever floats your boat. I guess I'm becomming out of step with ppl here in the marine, as well as planted forums, cause the main thing for me is the fishy occupant & the plants or corals provide a beautiful backdrop for them.

Cheers
TW

To each their own I guess Robyn. Despite what I say, I enjoy the fish, just not as much as the other aspects - plants, shrimps, and coral. I don't have enough resources to do it all, unfortunately, or I would have some fish only type tanks. I also get a healthy dose of fish at the store where I work, and get to "keep" a lot of different fish that way.

If you ever need someone to talk fish with, shoot me a pm or make sure I know about it in your thread.

Thanks for the nice comments though, not sure it will be stunning display tank, but I hope to have some stunning corals in it .

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Critical Fertilator: The Micromanager of Macronutrients