The Ultimate DIY Rocks!

[cougarguy]

Insane Reefer

I saw you were looking for some Hydrochloric acid, check out the flooring section in HD or Lowes it is labled as grout haze remover.

Some of them are Phosphoric acid but other are the Hydrochloric acid you are looking for.

[Insane Reefer]

Thanks Cougarguy

[Azazael13]

Originally posted by Insane Reefer
Awesome, AZ
Have you made rock before? If so, how did this compare for you? Are you pleased so far with the rocks? If your end pH is in the 9 range, would you say this method was worth it, as far as effort put forth and in time/water saved? Granted, the testing phase will make this take longer then it will once I'm certain most people will get the same results, and we feel that the long term testing isn't really necessary anymore, but I've been able to finish the kure in a week or so with a few water changes in the rock I've been doing lately, where I skip the testing phase - I've only had a few rocks that took as long as 2 weeks to do, from cast to finish.

Here is my rock history.
Phase 1: Too much water in my mix and stupid casting method. Trashed

Phase 2: In tank now not overly happy with them, but I need rocks in there and they aren't horrible.

Phase 3: Refining the process and am somewhat happy with these.

Phase 4: Your Jiffy style.

The faster cure is nice, but it won't matter to much to me since I am going to try to put them in my 10g this time around to help the algae outbreak, they will most likely sit in there for 2 months. I would love the baking method more in the winter, aside from the hot already humid summer

[Neptune777]

After soaking the perlite in zero TDS water overnight I still get a reading of zero TDS.

[Insane Reefer]

Cool AZ
Yeah, I discovered the low light thing through observation and by accident. I noticed that the rock I took to the local LFS don't seem to bloom, not like this backwall and other pieces I've seen. Didn't think too much about it until I threw a couple of pieces in my bug tank, which is a 10g with 15W? T5 of 50/50. These have never bloomed - they are still white (coralline just starting), though it has gotten a bit grungy colored. So last time I was in the LFS I asked what light was being used on the rock tank and it is a dual strip NO setup - very low light like my setup. The low light seems to curtail the algae growth.
Honestly though, if your system doesn't have a lot of stuff in it yet, I don't know that I wouldn't just go ahead and put it in there, and just run less light for a few weeks. Just a thought.

How about some pictures?

[Azazael13]

I will get pictures later today of batches 3 and 4(jiffypop)

My garage should be low light enough

[shookbrad]

Originally posted by Neptune777
After soaking the perlite in zero TDS water overnight I still get a reading of zero TDS.

I received the same results!

[Insane Reefer]

I left the perlite in muriatic for 24 hours - no reaction. I'd say this stuff is pretty inert...

After soaking the perlite in zero TDS water overnight I still get a reading of zero TDS.

The perlite does indeed seem to be truly inert.

One final test could be run for any doubters that might remain. Run the same series, but in saltwater, and leave it for a week. One thing I'd do would be to drop the pH in the saltwater into a range that buffering would naturally start to occur - say 7.5-8
I am sold already, though. I personally wouldn't bother with further testing.
My last remaining concern is something that will only be able to be tested for in real systems. The "Nitrate Sink" is something I worry about. After my "fight" with the jerk at the LFS about MMRL being a "Nitrate Sink" (though I think "detritus sink" would be a more appropriate term), I want to be able to say with conviction and confidence that this rock is a completely safe and healthy alternative to harvested or even cultured LR. Perlites "Filtration" and "Absorption" factors still make me wonder. But I am moving forward with Disco Dancing Rock (who I was told looks like the AOL avatar). I have some used saltwater from my weekend water change, that I will do a 3 day pH test in. If the pH is anything less than 9.5, I will put it in my bug tank.

We will see

[Insane Reefer]

Originally posted by Azazael13
[B]I will get pictures later today of batches 3 and 4(jiffypop)

Jiffy Rock! Not Pop - don't want to get me sued, do you? lol

[burblerboy]

Insane Reefer, I saw a link on the last split for colors to add, but the link doesn't work. I was wondering if you could post that again please, thank you

[Insane Reefer]

Originally posted by burblerboy
Insane Reefer, I saw a link on the last split for colors to add, but the link doesn't work. I was wondering if you could post that again please, thank you

V5.0 has a new link that works (I just checked it) - it can be found on page one of this new split.

[Neptune777]

Originally posted by Insane Reefer
The perlite does indeed seem to be truly inert.

One final test could be run for any doubters that might remain. Run the same series, but in saltwater, and leave it for a week. One thing I'd do would be to drop the pH in the saltwater into a range that buffering would naturally start to occur - say 7.5-8
I am sold already, though. I personally wouldn't bother with further testing.
My last remaining concern is something that will only be able to be tested for in real systems. The "Nitrate Sink" is something I worry about. After my "fight" with the jerk at the LFS about MMRL being a "Nitrate Sink" (though I think "detritus sink" would be a more appropriate term), I want to be able to say with conviction and confidence that this rock is a completely safe and healthy alternative to harvested or even cultured LR. Perlites "Filtration" and "Absorption" factors still make me wonder. But I am moving forward with Disco Dancing Rock (who I was told looks like the AOL avatar). I have some used saltwater from my weekend water change, that I will do a 3 day pH test in. If the pH is anything less than 9.5, I will put it in my bug tank.

We will see

Nitrate sink schmink! No way this stuff could be a nitrate sink unless you were forcing water through it like in a canister filter.....and in that case anything could become a nitrate sink.

[mr.wilson]

Your perlite rock will not result in any more residual nitrate than calcareous rock (live rock or aragocrete). The whole idea of an environment conducive to nitrifying bacteria leading to additional nitrification is a fallacy. Only detrital build-up can cause nitrate to climb.

Aerobic conditions and increased surface area do not increase nitrification. Any extra surface area will be redundant.

Perlite could indirectly increase residual nitrate if the core of the rock is more aerobic (more void space) and has less surface area. This would lead to diminished denitrifying capacity, as suitable sites for denitrifying pseudomonas are fewer.

Nitrifying bacteria have ample sites in a conventional tank, so there is no benefit to greater void space. Supplying enough real estate for denitrifiers is a greater concern.

While perlite may be slightly less efficient than calcareous rock, I can't see it having a measurable impact on the system, as long as you have a DSB as a substrate or remote.

I'm curious to see if it chips off in the water. I still have remnants floating in a terrarium after a couple of years.

[Insane Reefer]

Originally posted by Neptune777
...unless you were forcing water through it like in a canister filter.....and in that case anything could become a nitrate sink.

That isn't the only way - really porous rock tends to trap detritus - you can think of the voids as "poop holes". Detritus tends to settle downwards and collects, especially in those hard to reach places under other rocks, where it is difficult to remove. Those poop holes can get pretty nasty. Then say you have rocks getting blown pretty good with a powerhead - that would indeed force the poop into the rock deeper and deeper.

See where I'm going with this?

And perlcrete is the most porous thing I've ever seen. Seriously.

[spike78]

I think I've got the crumbles. After baking my rocks were hard as..well, rocks. After soaking them for a couple days, if I run my hand along them, pieces just pull out. If I get a good chunk out and squeeze it in my palm, it just crushes.

Am I just expecting too much too soon? Should I just let the rocks dry for a couple days before soaking them? Has anyone else had this issue? I'm wondering if when the salt is removed from the rock, it just becomes too brittle. Or maybe I'm just an impatient bugger.

I'm a bit frustrated at this point and hope I don't have to toss all the rocks I've done so far.

The mix I was using was 1 part oyster shell: 1.5 parts cement: 2 parts salt.

[Insane Reefer]

They shouldn't be crumbly if the bake went well - no one has had an issue doing this in an oven, so I am wondering if my thoughts that fire based heat is too harsh and dry, and there isn't enough moisture in the BBQ. I have had a couple of failed bakes, but those I can attribute to not enough moisture.
Only other thought would be that when you released the salt, the salt was more easily able to mix into the rock and upset the cure; one reason we typically mix the salt in at the end now - too many folks complaining of what you are seeing - friable rock. Usually this is an issue from the onset though - not rock hard, then suddenly not.

If they are this bad already, I'd scrap the lot - it will only get worse as time goes by.

I wonder. In regular cooking, especially over fire or in coals, one wraps the food in a heat resistant material to keep moisture in and to prevent burning - sometimes organic as in leaves, sometimes, as in modern times, with foil. I am curious for those who want to use the BBQ, if you wrapped the rock in wet newspaper or paper towels, then a layer of foil, what that might do. Probably wouldn't help, but it might. Just a late night thought...

[a1amap]

Originally posted by Insane Reefer
.
Only other thought would be that when you released the salt, the salt was more easily able to mix into the rock and upset the cure; one reason we typically mix the salt in at the end now - too many folks complaining of what you are seeing - friable rock. Usually this is an issue from the onset though - not rock hard, then suddenly not.

If they are this bad already, I'd scrap the lot - it will only get worse as time goes by.

I wonder. In regular cooking, especially over fire or in coals, one wraps the food in a heat resistant material to keep moisture in and to prevent burning - sometimes organic as in leaves, sometimes, as in modern times, with foil. I am curious for those who want to use the BBQ, if you wrapped the rock in wet newspaper or paper towels, then a layer of foil, what that might do.

How about the plastic baking bags they use for cooking chicken in?
I made my rocks over a year ago, while I didn't bake them I did have a batch that crumbled. My second batch was much harder and had a better mixture of sand and cement. I found if you use different types of sand, the bond is not as strong (ie. argonite sand makes a strong rock at first but then crumbles). I have some rock from the first try that is still breaking off. I use it as rubble rock for frags. The salt worked best when it was added last but not in great quanity. I reduced the the amout of salt mixed into the concrete and then pushed the remainder into the rock after I had formed it. This made craters from the outside in.

[mr.wilson]

I assume baking portland-based rock is similar to baking clay bricks. The low tech (olde school) method of baking clay bricks yields three grades, soft "salmon" bricks, medium structural grade bricks, and brittle dark "clinker" bricks.

The quality of the brick is governed by the temperature and duration of the baking process. The bricks on the outside get overcooked (clinkers), the bricks in the centre get undercooked (salmons), and the majority left are good quality.

It looks like some people may be overcooking the rock. There's a lot of chemistry going on during the curing process. I think it's safe to say that it's a process you don't want to rush too much.

[Insane Reefer]

Clay brick/block and cement brick/block are similar in their methods, but somewhat different from what I've read. With cement there is one grade - either it meets the ASTM standards or it doesn't. When baking, it either makes good cement or it fails - in the industry there are no middle grounds, at least in non third world countries. Or at least that is my understanding of it.

When the industry makes cement items, there are basically two ways they are done. One is a modern method and produces the quickest and most reliable results - they call it autoclave curing. This is a cure done in under twelve hours, within a pressurized chamber at a temps of 450°F, with steam provided. The older method, used often in third world countries, involves what amounts to a solar kiln, again with moisture added. Temps on these are not steady, and the cure takes a lot longer - typically temps are in the 175°F-225°F range, and rock can stay in there for up to two weeks.

We know that cement that is ready for building purposes can be cured in 12 hours. If it can be done that quickly, I don't think we are rushing it very much

3 hours at 450°-500° wouldn't be what I'd call over-baking. The worst batch of rock I've baked was at low temps - 225°F. At that temperature, there isn't enough heat to generate enough steam to keep the bake moist (lacking a pump and boiler, this isn't possible in the oven or BBQ), and I ended up with rock that sounds like what Spike is describing. His failed rock probably feels really light weight compared to the better piece, due to lack of pore water in the matrix.

[Insane Reefer]

Originally posted by a1amap
How about the plastic baking bags they use for cooking chicken in?

Welcome to the thread, a1amap!
Excellent idea! If they don't burn up on the BBQ that is. I've never used them before - are they BBQ safe?

I made my rocks over a year ago, while I didn't bake them I did have a batch that crumbled.

This happens, unfortunately - but not too often. Almost everything we do to make our rocks flies in the face of the cement industry - almost everything we do, according to the experts, is supposed to lead to failed cement, mainly in the form DEF (though there are other processes that can cause failure too), or Delayed Ettringite Formation. Which are basically crystals that form after the cement has hardened - there is no room in the cement matrix for these crystals, so the rock crumbles as the crystals form. Salt is a prime culprit in DEF. Our saving grace is that we are going for porosity, and this porosity gives enough space for the crystals to form, if they are going to, and so we often evade the DEF monster

I found if you use different types of sand, the bond is not as strong (ie. argonite sand makes a strong rock at first but then crumbles). I have some rock from the first try that is still breaking off.
...salt worked best when it was added last...

I would say it isn't from the sand - 75% of the rock I've made over the years has been with Southdown, but my Southdown is down to three bags being saved for my never happening 75G, so I am looking for alternatives. I like both the sand blasting sand and the limestone chicken grit. Both of these seem to work just fine. But of the old batches, only like 3 batches came out less than stellar, and those weren't due to sand failure.

The main difference I've come across has been between the rocks with salt and the rock without salt. I've only had one truly failed batch back in the day of non-salted rock. The other two were more recent and involved salted rocks. One batch had my batch too wet, and more salt leeched off. The other was my first salted sand and salt only batch and I mixed the salt in with everything else. I've made like 5 batches with salt/sand only now - small test batches, and each one varies a small amount on the consistency of the rock, though I am pretty good at getting consistent results without salt.
Salt is a wild card, IMO. If making the salt/sand only rock, expect randomness. After a few batches, you get an idea of how it all works, and what works best for you and your expectations, and will see less failed rocks. Anyone can make rock, but as with anything else, more practice makes you better at it. Always try small test batches when trying something new to you - that way, if it doesn't work out, you haven't wasted much time, effort or material.

I use it as rubble rock for frags.

The LFS actually asks for rubble for this purpose. I just give it to him - enough small, good pieces are left in the casting bins that it makes no impact on me and makes him happy

[Insane Reefer]

I'd like to take a minute to share some thoughts on Crumbly Rock. This is mainly for the Noobs, who haven't made very much, or those who have been disappointed in the rock they have made. Anyone else who wants to add their thoughts are more than welcome to.

First, I'd like to address "Expectations". I have a feeling that some people are expecting the rocks they make to be as hard as cement blocks or cement stepping stone, because, after all, they are made with cement, so it should be, right? Well, in this case, no - they won't be.
Let's compare our slurry to a typical cement pour slurry.
First, poured slurry's are made with a higher ratio of cement then we usually use. Next, they add enough water that they can pour the slurry - much like an ice cream slurry. I've never been able to pour my slurry; we try to make ours as dry as we can and still have it stick together. Then take a look at the aggregates - they use silica sands and gravel, we usually use calcium based substances when we can - there is a marked difference in each of these as far as strength goes.
And finally, when cement is poured, they try to get it settled down - they drag tools over it to smooth it and make sure it is even and all that. We go for as much openness as possible, and we try not to pack the slurry if we can help it.
Looking at it like this might help people come to a better understanding of what a reasonable expectation of their rock might be.
Our rock is going to flake and shed. The more porous the rock is, the more likely it will be to do so. The better the slurry is made though, the less you will see of it. Maybe you have seen a box of real live rock just after shipping. If you have, you probably noticed the rubble in the bottom. Most distributors are not in the habit of making up the extra weight in a box with rubble - that would be bad business. Most of that rubble simply came from the rock during shipping. Calcium based rock is not the strongest in the world, and essentially, our rock is calcium based.
But flaking and shedding are not the same as brittle rock. Your rock is brittle if you can snap large pieces off after a month or two. Small bits rubbing off is not necessarily indicative of failed rock, those could just be pieces that didn't get adhered well.

My first piece of advice would be to wait. It takes a month for the curing process to reach near completion and the rock to reach something close to its final strength. If your rock seems brittle or flaky, beyond what you should reasonably expect, just leave it alone for a month, in a moist (not wet) environment, like a plastic bag. Some of the early salt rock I made seemed really brittle, too brittle to use, certainly, for the first couple of weeks. It was when I later found it again, in the bottom of a bucket outside, that I realized how nicely it had hardened up. If after leaving it alone, you can easily snap sizable portions off (golf ball sized?), then you have a problem.

My next pieces of advice would be to use a stiff bristled brush, like what you use to clean your grill, to give your rock a good once over when it reaches about four weeks old (or after the pH test in Jiffy Rock). This will remove about 90% of the shedding and flaking, if your shedding and flaking isn't due to rock failure that is. If you have done this and a couple of weeks later it is readily shedding, then I'd say you might have a problem.

Remember that even slight variations can make a huge difference. Humidity and Temperature at casting and during the cure can make drastic differences. A tablespoon of water can make a difference on smaller batches - too wet and too dry can be a fine line. Differences in the cement itself can wildly vary - every plant uses its own recipe to make the clinker. Differences in local materials used for the recipe can ofter vary with availability and cost. My white cement is going to be different then Neptunes' cement, and his, even from the same plant as Sunkools' may vary as well, from lot to lot.

Salt can mess up the strength of your rock, so if you used salt, think about that. If you added it upfront, with the aggregates, you may have over-mixed it and too much salt mixed into the batch. Try adding the salt after the slurry is mixed and ready - and just lightly mix it in.
A ratio of 1:3 or 1:4 is best for us. 1 part cement to 3-4 parts "other", which includes salt.
If you are trying Jiffy Rocks, do not remove the salt prior to baking.

And finally, realize that even the best made rock can still chip and shed once in a while. Moving it around in your tank, bumping it against each other (esp larger pieces), will inevitably cause bits to shed or chip off, unless you went for rounded ball like shapes, which seem to loose less, but also seem less porous too.

I hope this helps a few people out there. I know that having something you worked hard on, that doesn't turn out like you wanted, can be disappointing. Hopefully this will help people understand what they should expect, and what they can do to correct it...

As always, comments and questions are welcome
If you have something to add, please don't hesitate.

[Yinepu]

Has anyone else had a lot of algae growth on the rocks while still in the fresh water kuring bins?....

Or are my rocks just strange?....

[Insane Reefer]

If they are where they will get good light, sure - they will grow algae; at this point the rocks are chock full of nutrients that algae just loves. That is why when they go into our systems they often bloom pretty good. The way I figure it, the more algae you get at this point, the less there will be nutrient-wise for the saltwater algae when you finally put it in the system...

[Yinepu]

Thanks IR..

the bins are out in full, direct sunlight... no lids.. and the algae is having a field day!... i will end up soaking them in saltwater in the bins before they go into the tanks...

[spike78]

Here is a picture of all my baked rocks to date and their possible tank position. I left them out of the water overnight and they seem to be pretty hard right now. I'm just worried that when I soak them, they seem to get soft and brittle. I don't want to put these in my new tank if they are just going to get soft, break, and foul my tank. I'm going to put them in a bucket and put them behind the shed and go look at them after a while.
I'm a little concerned with my design as well. There are lots of caves, holes and cracks, but the bottoms and tops of most the rocks are pretty flat, am I going to have problems with flow in these areas?





I'm expecting my tank in about 6 weeks so I'll have to make a decision whether to use these rocks or not. I figure my choices are these rocks + 100# of Marshal Island, or 175# of Carlos Rocks with 50# of Marshal Island.