The Ultimate DIY Rocks!

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Rick,
You will find lots of threads (and even here) where folks have used either HCI or Muriatic. Both are strong, and you are correct - muriatic is a dilute form - but also keep in mind that muratic is used to clean cement off of other stuff.
The problem is that acid weakens cement - you might say, "So what?", however, with the addition of salt to the mix, we have already weakened the cement considerably; so we are trying to find a gentler solution (pun completely intended!) that won't be as aggressive on the cement.
Does that help?
 
And I am putting the tests batches into their acid bath in a few minutes. The rocks are just shy of 48 hours old.
The salt released just fine from my regular recipe "ol' skool+" batches - the salt and sand rocks though - I ended up boiling those for an hour or so in addition to soaking - those puppies were dense. I'm still not convinced all the salt is out completely on that batch, but will proceed to kure - a little salt won't hurt anything, and it is all part of the experiment anyway...
 
Also, I made a small batch of rocks last night just to check out. It has a ratio of 1:1:2 of Sand:Cement:Salt. I can't wait to see how fast all of this Kures. I hope to have my 75g running with water in the next month or two.
 
<a href=showthread.php?s=&postid=9967800#post9967800 target=_blank>Originally posted</a> by medic29
Actually, muratic acid is a dilute form of hydrochloric acid; thus the reason why it is used for swimming pools.
This is a common misconception, because it is sort of almost half right. Muriatic acid is a lower grade. It includes allowable contaminants that stain it a yellowish color and may make it less effective. Muriatic acid is fine for scrubbing excess mortar off bricks and rock work. The contaminants in it are going to get washed away in that kind of work.

If you dilute hydrochloric acid with clean water it does not become muriatic acid. It becomes dilute hydrochloric acid.
 
And that's why we keep Rhody around - he keeps us all on our toes and fills in the gaps :)

Travis, FYI. You know how a couple of months ago, we were sort of debating which recipe made the most porous rock? And if porosity can be sort of determined be how quickly salt comes out during the release, then I have an answer to that question. The "Ol' Skool+" is most definitely more porous than the sand/cement/salt recipe...

I was really careful to cast these batches the same way, and to cast them as dense as I could by packing the cement down pretty good. I wanted dense, thick blobs, and I got those. Batch 1 and 2 are both clear of salt - batch 3 still has a lot of salt, even after an extra soak and a hour boil. I didn't cut them open yet, will do that after kure, but I am not afraid to taste my rock - it is a great gauge for telling if any salt remains, and 1 and 2 were both "sweet", and 3 was salty as a bag of chips...

I am going to cut these open with a diamond blade - folks have been asking to see a cross section and I finally found the blade, so once these are pulled from the acid kure, I will cut one from each batch open.
 
<a href=showthread.php?s=&postid=9968612#post9968612 target=_blank>Originally posted</a> by Insane Reefer
Rick,
You will find lots of threads (and even here) where folks have used either HCI or Muriatic. Both are strong, and you are correct - muriatic is a dilute form - but also keep in mind that muratic is used to clean cement off of other stuff.
The problem is that acid weakens cement - you might say, "So what?", however, with the addition of salt to the mix, we have already weakened the cement considerably; so we are trying to find a gentler solution (pun completely intended!) that won't be as aggressive on the cement.
Does that help?
Rick, to clarify a bit further - muriatic acid sold at most retail outlets is marketed primarily for etching the surface of solid concrete slabs. Then it is neutralized, usually with a water wash. The internal core area of slabs treated with a muriatic acid wash are typically not affected by the acid.

But with this rock that we produce with the addition of rock salt, the rock is not dense, like a slab. Due to DIY rocks very porous nature, the muriatic acid could easily penetrate most all of the interior mass in quick order. Thus, weakening the rock to its core. And that is a major reason (in my mind) to not use it on DIY rock.
 
Great stuff. I shoulda been on top of this before. I have been delayed for 8 months in putting up my 180 (it's been excruciating). Now I see this and I gotta do it but it slows things down more.



Now I can lay out my aquascaping and achieve it much easier. Anyway, here is my first thought that I don't see anyone addressing. My first set of rocks will bee the base of the scape and will be covered by the sand bed (5"). The other rocks will rest on this.

Any problems/thoughts about using these mm rocks that way?
 
Daven, not a problem at all. THe rocks are just as strong as the real thing, so there won't be a problem

Insane Reefer, forgive me. It's been a long, hard week and I'm absolutely brain fried. What do you mean by old school? Are we talking Crushed Coral, Sand, and Cement? This is what I think of when you say Old School.
 
Hey guys, thanks for clearing this up for me. I had wondered why no one had used the muriatic acid. It pretty much makes sense. It still makes me wonder if there is a way to add something to the water to dramatically lower the pH and thus speeding up the process.

So, did I hear someone uses vinegar? My water out of the faucet has a pH of or over 8, so trying to get the pH down to 8 seems to be taking quite a while. Would using straight vinegar work. I'd think that would get kind of expensive after a bit, but adding a bunch of vinegar to a tub of water wouldn't be too bad.

What is everyone else doing??
 
Yes, Travis, "Ol Skool" is the traditional sand/cc/cs like GARF made popular - I have taken the liberty to adding salt to it, making super porous "Ol' Skool+" :)
I imagine in a typical, loose cast, that the sand/salt recipe you prefer will release just fine, however it does not like to be packed. And if someone has problems with this recipe and getting salt to release, I will most likely think that it was too densely packed.
Rick, vinegar is something we are returning to. For a long time, it was being used for the wrong purpose, and so little in the way of results was ever gained, really. But with better understanding, we are starting to think that instead of using it to "quik kure" the rock, it could be used as you suggest to lower the pH of the water and allow fewer needed water changes.
 
Baking Tips and Observations

Baking Tips and Observations

For those of you like Travis, who are trying the new method for rock making, I am posting some tips and observations I've made over the last 2 bakes.

1. Use foil to cover the bottom of your stove as well as each rack you leave in. Efflorescence will be pulled out of the rock and form tiny puddles where your rock touches the foil. Your rock will be glued to the foil at these points, so when you pull it out, sand may go everywhere if you are not careful. Foil on the oven floor will prevent having to clean the stove so much afterward, and make the head of your kitchen happier with you.

2. Use a metal pan or the like in the oven to provide plenty of moisture. Half-way though the bake, check the pan to make sure it has water left in it. A dry bake will not produce the results you want.

3. Some stoves have a vent under one of the back burners. If you can, cover this vent with a metal cup. You may have to loosen/remove the burner to do this, but this will prevent the loss of too much moisture.

4. Turn off the houses' internal fans, etc. You want the fumes to remain confined to the kitchen. The fumes are nasty, mostly just the smell is bad, and not harmful as long as you don't go hang out in them. Use a fan in the kitchen window, and open the windows in other parts of the house to form a draw though. This will help with fumes.

5. When bake cycle is done, just turn off the stove and leave the rock lone for 2 hours. While the rock is hot, you will be in the greatest danger you will face - plunging your rocks. I think this exponentially speeds up salt release, especially when really hot water is used. If the water you use is too cool, and the rocks too hot, they could explode, so be careful, and wear gloves and goggles for this step!

6. I will recommend to folks making the salt/cement or salt/cement/sand recipes to actually boil the water they use for release, and if possible boil the rocks themselves. I had a lot of trouble releasing the salt from these (though I don't make this recipe often, so that may be part of it), and if you are at the stove anyway, this will make it go faster. If you boil the rocks, just make sure to us a pot that isn't going to be missed - you will more than likely not want to use it for food after this. Salvation Army or GoodWill might be places to find cheap stockpots for this.

Ok. That is all I can this of for Baking tips. I will of course answer any questions, if I can.
:)
 
Hey just wanted to get involved in this. I was reading over the many pages on the subject and last week made a trip to HD. I knew that they wouldn't have white portland cement but I did find a 50# bag of white mortar mix used for glass block mortar. It uses white portland cement, sand, and somekind of limebase product in it. Has anyone tried this product or not? Just trying to not run all over town for ingredients. Also in the garden area they had pulverized limestone(dolomite), was wondering if this would be good for sand mix or should I stick with play sand? I thought I read something on here about it but don't remember.
 
Can you get & post the MSDS for the glass block mortar?
That sounds like it might be a more readily available source for those that want white rocks to start out with

thanks!
 
"Composition and Materials: QUIKRETE Glass
Block Mortar consists of a uniformly blended
mixture of white sand, cement, lime, and
chemical additives designed to provide a
decorative, waterproof joint."

It is the waterproof part I don't like. That and extra lime will mean a long kure + lime = fertilizer...
 
Well thanks for raining on my parade IR :) I quess we wont know unless we try right. I will try this week coming up with GBMM and the regular grey PC and see what the difference is and post my results back up here. Either it will work and save some people a trip or it wont and I'll be out $10. We live and learn right.
 
One more question, is there a difference in the sand you use? would any type of play sand be alright to use or is there some specific I should look for? HD had about three or four different types of sand from play sand to concrete sand mix, is one better than the other or should I get whatever is the cheapiest? Thanks again.
 
Insane Reefer: is it too late to be one of the monkeys?? It took me the better part of 2 hours to read the last several pages of this thread...which was only about 4 days worth....wow. Anyway, I found your "recipe" of sorts and the "baking" part. I hadn't tried that before and am curious how it might speed things up.

I'm going to try to make some rock today, then let it set for a couple of days. This should get me to Monday. I'm at home all day alone so this ought to be a good day to fire up the oven and make the house stinky, then I should have time to get it aired out pretty good before anyone gets home.

I do have a couple of questions though...when making the water for the salt release you had stated it needed to be hot; I had thought about picking up a big stock pot and filling it with water and putting it on my burner for the turkey fryer. Since it is propane and burns hotter than the inside stove, plus this way I can keep the water hot while "plunging" the rocks. Then turn off the burner and let it cool. Then later fill the container up again and fire the burner up and get the water to boiling again and repeat the process. Does this sound like an okay plan? Would there be any benefit to boiling the rock/water for a while?

Then should I put it in a cheap kiddie pool or get a rubbermaid tub and put the rock in it with the vinegar/water solution with a mj pump?

Let me know. I would like to try getting involved in this and posting my results as well.

Thanks
 
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