Agrocrete Rocks!

tekknoschtev · Mar 26, 2006

About a month or a month and a half ago I made a ton of agrocrete rocks.

Thats what they looked like before being washed and cured. That being said, the vast majority still isnt cured, but thats due to not having enough toilet space to cure all of them.

Here's some close ups of some pieces that have the sand washed off and the rock salt melted out:

The last one shows what the rock looks like on the inside (I smashed a rock open). I have to say that the new mixture is far superior to my old mix. The new mix consists of 1-2 parts Portland Cement, 4-5 parts limestone sand, and 3-4 parts rock salt. I'm thinking that in the future I should have more salt than sand but this stuff is fairly light (the rock structure above weighs a total of 34lbs with all of the residual sand and rock salt in it).

Worked out pretty well, and I'll DEFINATELY be making more of it in the future to suppliment the rock in our 150, to also add to the rock in the puffers tank, and for mounting frags too in the frag systems we have running.

Russ K · Mar 26, 2006

That looks really nice. How pourous is it and how big is that rock structure? My brother and I were getting ready to make a bunch. He has a 110 long and I have a 180. I need more for next winters tank upgrade and would like to get my big sump going with this in it in the next few months and he needs some for his 110.

Have you tried to make any caves or bigger structures with less pieces to avoid avalanches?

tekknoschtev · Mar 26, 2006

The whole structure would probably fit into a box 28"x12"x16" (roughly).

My biggest reccomendation when doing in volume - HAVE SPACE. I had to stop at what you see there because I ran out of rubbermaid tubs to put the sand in to mold them (though I in theory could have free formed them, I didnt want all blobs

) The individual pieces you see on my green towel are about 3-4".

As for porusness - like I said I wish I had more salt than sand but these are very porus. I'm going to revise my next batch to be 1-2 parts concrete, 2-3 parts sand, and 4-5 parts salt. It will be another test batch like this, and if it works better, I'll stick with that, but thats a few weeks (months?) off.

Soulfigter · Mar 26, 2006

Very good job on it, and thanks for sharing it with us.

jblabs · Mar 26, 2006

Looks nice!

Russ K · Mar 26, 2006

I plan to set up a sump hopefully the 300 gal. rubbermade tubs from tractor supply late summer plenty of room for curing and to house the livestock while new tank is being set up. We'll see and I'll keep my fingers crossed I can do it then.

Everything is in my basement.

tekknoschtev · Mar 26, 2006

Good luck Russ! Eventually I plan on having closer to 100-200lbs of agrocrete rocks in my frag system. I've read that it isnt as effective as "real" live rock, however, I believe that it will be ok, as long as its supplimented with a decent proportion of "real" live rock.

Russ K · Mar 26, 2006

Well I am assuming that if its pourous enough and in a tank long enough it will in a sense become (live) just a good as true LR.

I guess the question I have, is by the time you buy material, make the rock, and clean up the mess; is it cheaper just to buy base rock at volumn prices. I would have to do the curing regardless.

pista01 · Mar 26, 2006

Russ K said:
I guess the question I have, is by the time you buy material, make the rock, and clean up the mess; is it cheaper just to buy base rock at volumn prices.

Yet another thing to consider is flexability. You can make all kinds of shapes with agrocrete. That's worth a lot for me.

tekknoschtev · Mar 26, 2006

Russ K said:
Well I am assuming that if its pourous enough and in a tank long enough it will in a sense become (live) just a good as true LR.

I guess the question I have, is by the time you buy material, make the rock, and clean up the mess; is it cheaper just to buy base rock at volumn prices. I would have to do the curing regardless.

Hmm, lets see. 94lb bag of Portland Cement - $6. 450lbs limestone sand - $9.40. Rock salt - $20ish for enough to make it. Total cost ~$36. I've made close to 100lbs of agrocrete rocks. That works out to $0.36/lb, and the best part is I still have at least 50% of each supply left (more so of the sand

).

pista01 said:
Yet another thing to consider is flexability. You can make all kinds of shapes with agrocrete. That's worth a lot for me.

Yeah, agreed. I like being able to make cool looking "caves" and ledges exactly how I need them (or at least how I think I need them). I love the flexibility.

Russ K · Mar 26, 2006

Thats A big dif. in price. If you can get another 100 lbs for the same material than at .20 a lb compared to about 1.50 lb shipped. I'll probably make my own too then. Huge savings and I can make some really nice size peices.

thx. 200 lbs would cost me 300 bucks compared to about 36

billfraley · Mar 27, 2006

What is the curing time? and when you use rock salt, how long does it take for the rock salt to dissolve. And what about the phosphates from the concrete, how did you deal with it?
I did hear that when you put it into your tank, place plenty of LR around it and it will soon create coraline and host pods and such. What I really need to know is, "when is it safe to put in the tank without killing everything". Iwas thinking the lime from concrete was bad for a reef tank. This is a real cost savings and I would like to learn more about it.
Bill

Reefdaddy · Mar 27, 2006

Here are some of mine from about 2 years ago

Notice the caves?

I been making this stuff for quite sometime now. Its easy cheap and definatley worth the effort. And coraline does grow on them very well. as long as they are fully washhed and cured. I cure in 100 gal tub with high flow and frequent water changes. They cure in abpout 3 weeks that way. The tank setup was temp till I was happy with water quality. Plug holes are in all tops for easy frag attachment. Currently I have about 700lbs of this stuff in my tanks. could not be happier. As soon as I get my Camera back I take pics of the stuff already covered in coraline.

tekknoschtev · Mar 27, 2006

billfraley said:
What is the curing time? and when you use rock salt, how long does it take for the rock salt to dissolve. And what about the phosphates from the concrete, how did you deal with it?
I did hear that when you put it into your tank, place plenty of LR around it and it will soon create coraline and host pods and such. What I really need to know is, "when is it safe to put in the tank without killing everything". Iwas thinking the lime from concrete was bad for a reef tank. This is a real cost savings and I would like to learn more about it.
Bill

Curing time varies based upon which toilet we use to cure them in. The downstairs toilet back home gets used quite frequently, whereas the upstairs one is more of a morning and night situation. The one in Lansing, because its used mostly only by me takes longer. The batch at home took approximately three weeks to cure. I dont have a pH test kit (and every time I go to Preuss I forget about bringing a water sample or buying a test kit) so I dont know how the ones here are doing, but I'd imagine that by the time I go home this Friday, that they'll be cured. The ones that were pH tested at home are already in the sump getting some of that live stuff growing on them

As for the rock salt, the stuff on the outer edge/layer of the rock disolved over night. I've been breaking rocks open to see the inside, and generally within a week (very very conservative) its all disolved - most times within 2-3 days.

Phosphates from concrete... hmm, never thought about that aspect. I personally would suspect due to the very low amount of actual concrete in the mix that it wouldnt be too high but now I feel like doing a test by having a ton of the rock just sitting in a bucket of salt water for a while to test the phosphates. One day when I have some time.

As for whan it is safe for the tank - I've gone by the pH curing rule. That is, initially when mixed, the concrete will raise the pH of the water to sky high proportions. Over time, with regular water changes (and I've been told with flow and aeration it increases the curing time) the pH will begin to drop. We let ours get down to 7.4-7.8 before we put it in the tank. It takes a little bit to get coraline growing on it, however, once it starts, the rock quickly becomes nearly indistinguishable in the 150.

DLBerlin · Mar 27, 2006

Wow those look great Steve-better than any dry base I've seen. Next time you come down I can give you a bunch of styros to work with if you want them. I dont need them but I just cant throw them out!
As for the phosphate-concrete question I do know that people have been making and using this stuff for years and have had no problems with it. Very safe as long as it's cured.

tekknoschtev · Mar 27, 2006

Thanks Debbie! I'll have to make it a point to stop by sometime in the near-ish future.

I figure that the cost savings, coupled with the fact that I can make them exactly how I want negates the work put into it so they do work out to ~$0.20 cents each when all is said and done.

hanzlowsky · Mar 27, 2006

Could you describe the process of molding the rocks?

Is the mixture really "liquidy" or more clay like?

tekknoschtev · Mar 27, 2006

For molding the rocks, I put down a layer of sand a few inches thick, and then use a spray bottle to get it moist (not wet, just moist) and then I can dig into the sand a bit to make a mold. Then I put down a blob/layer/etc of the agrocrete mixture. If I want to make caves, you can throw a layer of sand on top of the concrete in part and then another line of agrocrete. After all of that, I throw a layer of sand on top and then start the process over until theres no more room in the tub.

The mixture is fairly dry. If I have some intricate shapes I make it a bit more liquidy, but in general its pretty dry and chunky. Next time I make a new batch I'll get some pictures/videos of the process.

hanzlowsky · Mar 27, 2006

The sand you use for molding; how big are the grains?

tekknoschtev · Mar 27, 2006

They range from dust size to rather large (for sand). No where near pea-gravel. You can see the larger chunks in the pictures.

Agrocrete Rocks!

tekknoschtev

Russ K

tekknoschtev

Soulfigter

jblabs

Russ K

tekknoschtev

Russ K

pista01

tekknoschtev

Russ K

billfraley

Reefdaddy

tekknoschtev

DLBerlin

tekknoschtev

hanzlowsky

tekknoschtev

hanzlowsky

tekknoschtev

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