The Ultimate DIY Rocks!

[jasonh]

Originally posted by cayars
Amen to that!

Speaking of "making rock" I pulled a bone-head maneuver. I unloaded 5 larges bags of white Portland cement and put them under an awning yesterday next to my grill. After a couple of drinks last night I hit the button to retract the awning to find 500 lbs of wet cement this morning.

Hopefully the 3 bags in the middle are ok. I "knew" I should have put them in the shed but was feeling lazy! I didn't really feel like making any rock this week anyway.

Carlo

ouch. Sounds like something I would do, lol.

I'm paranoid now though, so all my stuff is in a 57gal rubbermaid, except the perlite because the bag is so big. Once I start casting a lot of rock, that'll change though. No idea where I'm going to put all this stuff, my balcony is tiny

[Insane Reefer]

Anyone using a pre-mixed (bag) cement to make their rocks needs to just step back and think for a minute.

Pre-mixed cements and grouts/mortars already contain sand and do you really think they contain calcium based sand? No, they contain silica based sand.

I'm sure the beaches of Florida have silica sand, but they are likely the result of the tourist industry.

What? Where on earth did you come up with that?
http://geology.wr.usgs.gov/parks/coast/beach/index.html

This link is sponsored by the US Parks division, and is all about the sands of beaches. According to them, most beaches are made of silica sand, but of course, they may be wrong...

[jasonh]

Does anyone have a silicate test handy and some spare time? I've come up with a test I'd like to perform, but don't have a test kit, nor the space for extra buckets laying around (they are scraping paint/repainting the building for the next couple weeks, so I have to keep as much crap as possible off my balcony).

Anyway, here's just something quick I thought of:

Grab 4 buckets. These could be 1-2 gal. Fill one with just water...lets say 1 gal. This will be the control. Fill the next with 1 cups of silica sand, and 1 gal of water. For the next, mix up a batch of cement containing 1 cup portland, 1 cup silica sand, 1 cup whatever else (OS maybe). Form this into a generic ovalish rock shape, and let cure (either by baking or whatever you prefer - baking would be quickest if you don't have quick setting concrete). After curing, place this rock in the bucket with 1 gal of water. For the last bucket, make an identical batch of cement, substituting the silica sand with something else - more OS, aragonite sand, whatever (as long as there is no silica in it). Cure this exactly the same as the first.

Take silicate readings every day or two on all 4 buckets, and compare numbers. This should at least give us a nice look at what effects this cheaper and more readily available aggregate would have on our tanks. My guess would be that significantly less silicates would be available when used in the rock than when just dumped into the bucket.

If nobody has any interest in this, no biggie, I'll just end up doing it when time and space permits This is something I am personally very curious about.

[mr.wilson]

Originally posted by Insane Reefer
Anyone using a pre-mixed (bag) cement to make their rocks needs to just step back and think for a minute.

Pre-mixed cements and grouts/mortars already contain sand and do you really think they contain calcium based sand? No, they contain silica based sand.



What? Where on earth did you come up with that?
http://geology.wr.usgs.gov/parks/coast/beach/index.html

This link is sponsored by the US Parks division, and is all about the sands of beaches. According to them, most beaches are made of silica sand, but of course, they may be wrong...

They also mention that tropical beaches (Florida) have calcium carbonate-based sand. The silica beaches are up north where there are no coral reefs to influence the beach sand.

To the best of my knowledge, the beaches of Florida are comprised mostly of algae hash (calcareous algae skeletons like halimeda) that have washed ashore.

This sand is rich in phosphates and is not typical of reef sand.

[burblerboy]

I don't know about the whole state, but all the beaches in S. Fla. are dredged offshore and pumped in. All of Miami Beach is man made over the last 40 years. I just went to a turtle release and got educated on this as part of the mandatory presentation to be part of the release. It was so COOL to see these little guys. Sorry for getting a little off topic.

[Rhodophyta]

Originally posted by cayars
Amen to that!

Speaking of "making rock" I pulled a bone-head maneuver. I unloaded 5 larges bags of white Portland cement and put them under an awning yesterday next to my grill. After a couple of drinks last night I hit the button to retract the awning to find 500 lbs of wet cement this morning.

Hopefully the 3 bags in the middle are ok. I "knew" I should have put them in the shed but was feeling lazy! I didn't really feel like making any rock this week anyway.

Carlo

Looks like you made some rocks anyway, unfortunately in the shapes of large bags of cement.

[cayars]

Yea, I made "Moon Rocks", yea, yea that's the ticket.

[eshook]

Could you sledge hammer them apart? Just re-cement some of the pieces back together in odd shapes. I would think you could re-use the giant cement bricks only in smaller form.

[cayars]

I use pure cement cubes/bricks in a couple of pH reactors hooked to my ACIII so it won't go to waste.

BTW, cement is the "best" way to raise/keep your pH steady if you have a controller.

Carlo

[michaelalan]

One thing that I have been thinking about as far as lowing pH is adding Sulfur to the cement mix. Sulfur lowers pH and when used like a calcium reactor it reduces nitrates. Nurseries sell it for lowering the pH in soil. According to the instructions for the soil applications sulfur gets used up, probably thru dissolving into water and being carried away.

The implications of this is that the sulfur would disappear from the rock leaving the holes we all covet from the use of salt.

The unknown is that that cement hydration is a chemical reaction and throwing large amounts of sulfur into the reaction could cause fumes and potential health problems.

Insane, can you pose this question to your cement experts?

[argetni44]

this is incredibly innovative

[mr.wilson]

On the subject of sulfur reactors...the guy in the third post in this thread seems to know what he's talking about.

http://www.njreefers.org/joomla/inde...&topic=4537.15

[cayars]

Originally posted by mr.wilson
On the subject of sulfur reactors...the guy in the third post in this thread seems to know what he's talking about.

http://www.njreefers.org/joomla/inde...&topic=4537.15

Yep, been using them for many years to run pretty high bio-loads like 30 nice size fish in a 110. When I moved earlier this year I moved my 110 (now agressive tank) to the new house (garage) but took the fish me with in a 44 g pentagon tank at a hotel for 10 days. The 30 fish were just about bumping into each other but the nitrates were just about zero thanks to the reactors.

michaelalan, Man this is to funny. After Mr. Wilson brought up the link about NJReefers a couple of days ago I had thought about trying sulfur in the mix.

I tried using "beads" (reactor beads) but they just pretty much stayed whole so that didn't work unless you like brown "marbles" in your rock. I took a trip to Agway yesterday and picked up some agricultural sulfur which is much smaller. I think this will mix better. I know I tried it previously in a reactor and it went to "mush". Hopefully this will mix well and give us good results. Time will tell.

I'll let you know the results once it stops raining and I get a chance to mix up a batch. I'm going to use straight sand and white portland for this test at a 3:1 ratio. This way it's kept basic without the other chems thrown in.

Carlo

[Insane Reefer]

Here Michealalan.

The use of sulfur as a binder in the preparation of concretes when combined with an aggregate such as crushed rock or gravel has also been investigated. However, after solidification the sulfur in these concretes undergoes allotropic transformation wherein the sulfur reverts to the more dense orthorhombic form which results in a product that is highly stressed and therefore vulnerable to failure by cracking.

But a lot of folks are working toward something that will work:
http://www.patentstorm.us/patents/7001454-claims.html

I found this with google. I was planning on writing to him later tonight or tomorrow - will ask him about this too, but I think he will probably not have much to say...

[cayars]

I just read that twice and still don't know what I read.

Carlo

[Insane Reefer]

I think, simply put, that it says that it makes a cement that is likely to fail.

[michaelalan]

Carlos, I can't wait to hear about your results with sulfur.

[mr.wilson]

I would guess a very small amount of sulfur would have to be used to assure it doesn't leach into the water column.

From the dissolution rate I've seen in sulfur reactors, it would dissolve within six to nine months within a rock. Nitrate will not accumulate in a new tank within that time, so it may not serve a purpose.

It might be something better left for a reactor where it can be monitored and controlled.

[Insane Reefer]

I've sent an email to my guy in England about sulfur - I will report what he has to say.

...it would dissolve within six to nine months within a rock. Nitrate will not accumulate in a new tank within that time

What do you consider accumulation? My not quite 5 month old Biocube had Nitrates of around 60 before my last water change and adding another rock...

[mr.wilson]

Originally posted by Insane Reefer
I've sent an email to my guy in England about sulfur - I will report what he has to say.


What do you consider accumulation? My not quite 5 month old Biocube had Nitrates of around 60 before my last water change and adding another rock...

Things happen much faster in a 10 gallon tank, as the bioload is greater and the addition of a single coral can adequately seed the tank with bacteria. Your system also relies more on biological filtration in the absence of protein skimming, macro algae culture, ozonation, and UV irradiation (assuming you haven't modified your system to accommodate these). Larger, more elaborate systems circumvent the nitrogen cycle to a certain extent by employing other means of assimilation, nutrient export, oxidization, and molecular absorption.

Typical stock levels in a 120-240 gallon tank over the initial months of set-up take much longer for nitrate to accumulate. A system using live rock will have an established nitrogen cycle in a relatively short period of time, but a tank using exclusively base rock will take 3 months +- for nitrate to start to accumulate, and another 3 month or so for it to reach a significant level. Nitrate reduction doesn't factor into the equation of establishing a new tank.

The value of concrete with a sulfur core would be in its' use as a reactor media, or passive media in sump. It would solve the common problem of sulfur clogging while offering clog-free buffering capacity. A cement rock with sulfur in the centre would work similar to Aqua-Medic Multiballs, only disposable.
http://www.aqua-medic.de/seawater/en/19/multiballs1/

BTW 60 mg/l is awfully high for a 10 gallon tank. Are you doing weekly water changes? Do you have detritus build-up and or a heavy bioload? Do you use carbon, ion exchange resins, or any other chemical media?

[michaelalan]

insane - mr wilson. ya'll might want to start a new thread

[Insane Reefer]

A reply from Nick in England:

Sulphur: I've never heard of adding sulphur as sulphur (ie: S and not
SO3). Not sure what would happen. If it oxidised to sulphate you would
probably get sulphate attach with cracking and general weakness. If,
not it might just give a yellow mix. Can't see the point myself.

Cement needs a high pH to react. If you lower it you will slow the
hydration. I think you need to think in terms of not mixing anything
into the mix to lower the pH but (if you must) lower it afterwards when
it has hardened eg: with fizzy water.

[Insane Reefer]

Originally posted by mr.wilson

BTW 60 mg/l is awfully high for a 10 gallon tank. Are you doing weekly water changes? Do you have detritus build-up and or a heavy bioload? Do you use carbon, ion exchange resins, or any other chemical media?

IMO, 60 is high for any aquarium. The nitrates are due to lack of rock (I only have a few small pieces and some rubble in a rear compartment) and lack of water changes (since I had only inverts and softies I was getting lazy). And I think a sand sifting snail died and did so in the sand bed where the hermits couldn't get to it.
With the addition of Bogo, the tail spot blenny, my tank cleaning habits will get better, though he is a piggy little fish and I may now be over feeding the tank - I don't know, but it seems everything I throw in gets eaten by something, pretty quickly.

When the centerpiece is ready, I should have enough rock to handle the load.

[Insane Reefer]

Nick had, what I believe to be, a great suggestion. I've picked up a bag $5.99 for 50#, which makes this half the price of my white cement. Would also lighten the color of grey portland, I think.
I will give it a try and post the results.

How about substituting lime for some of the cement? Lime has a lower
pH than cement (no sodium or potassium hydroxide). Make sure it is
slaked lime - calcium hydroxide. Don't use quicklime - calcium oxide.
Or use a strongly hydraulic lime, ("eminently hydraulic" in European
terminology) as used traditionally for masonry if you can get it. If
not, a blend of 10% or 20% white cement and the rest as lime should be
OK. Obviously, lime is caustic too so take the same precautions as for
cement.

With lime, you should get a purer rock in the sense of a higher calcium
carbonate content compared with cement. It won't be as strong and it
may take longer to set and harden but the final product should be
better, provided it is strong enough. There will be less aluminium as
well. If you use limestone aggregate, you will have a product that is
maybe 90% limestone by the time it has all carbonated.

[bigtex52]

IR, what you are describing by replacing some of the cement with slaked lime is commonly known and comes prepackaged as Mason's Mix or Mason's Pre-Blend. It is simply Portland and Slaked lime premixed. Type S is probably what you want as it has a higher compressive strength than Type N ( which has a medium compressive strength). HD or Lowes probably carry it as well as all masonry supplies. Don't confuse it with Mortar Mix though, as that has the sand added.