Concrete In A Saltwater Tank?

BRDrew
  • #1
I work in construction and I recently found a manufactures that makes incrediply porous concrete blocks. He uses some kind bacteria to make the block take in CO2, much like bread, and it looks pretty much like marine pure media.

Has anyone here ever have concrete inside their tank? Does it change the water chemistry? I was wondering if I could give it a try as media.
 
Jesterrace
  • #2
I wouldn't as you have no clue what all has gone into that mix. My biggest concern would be toxins and that phosphate would be off the charts with all the various minerals that go into mixing concrete and I can't imagine that concrete would do well in saltwater given that concrete weathers when exposed to various salt mixes.
 
Mr Clown Loach
  • #3
I wouldn’t within the concrete there are most likely some form of chemicals that are not safe for fish. I’ve heard of a simple mineral from rocks killing off a whole tank.
 
BRDrew
  • Thread Starter
  • #4
I will try getting a list with the composition of the concrete so we can check. Also I'm not quite sure it would wear down too fast, Ive seen the blocks being used submersed, not in Saltwater but submerged anyways.
 
Reeferxbetta
  • #5
I wouldn't. I'm not really understanding the point of putting bricks in the tank, I get that the marine pure stuff is supposed to be really porous and hold lots of good bacteria, but good quality live rock should achieve the same thing. Maybe that's just me, I don't see the point of adding any "bio media" type stuff to my saltwater tank, I prefer to just let the live rock take care of that.
 
BRDrew
  • Thread Starter
  • #6
I wouldn't. I'm not really understanding the point of putting bricks in the tank, I get that the marine pure stuff is supposed to be really porous and hold lots of good bacteria, but good quality live rock should achieve the same thing. Maybe that's just me, I don't see the point of adding any "bio media" type stuff to my saltwater tank, I prefer to just let the live rock take care of that.

It is a matter of availability and having the option to use media other than live rock. It took me some time to gatter everything I need for my Saltwater set up, and even now that I already have nearly every piece of equipment live rock is going to put a significant dent on my pockets for the size tank I got.

Dont get me wrong I'm not trying to get some kind of backwards discount on this, I have already ordered the live rock at my LFS.

I just wonder about it for future reference. Maybe this thing could be some viable economy-class media.
 
Reeferxbetta
  • #7
What size tank did you get? Dry rock can be found for $2 a pound (I've even seen it for less) but yeah, live rock is expensive, I have about 65 ish pounds of it, and it wasn't cheap. I get looking to find different media for the tank, but I think live rock will do you better than bricks, but that's just me. Have you figured out what they're made from yet?
 
BRDrew
  • Thread Starter
  • #8
What size tank did you get? Dry rock can be found for $2 a pound (I've even seen it for less) but yeah, live rock is expensive, I have about 65 ish pounds of it, and it wasn't cheap. I get looking to find different media for the tank, but I think live rock will do you better than bricks, but that's just me. Have you figured out what they're made from yet?

I got a 40G all in one that was adapted to be used with a 20 gallon sump. And while dry rock is quite cheap in the US but here in Brazil it is still remarcably expensive. Life rock here goes for 32BRL/Kg and dry rock goes for 25BRL/Kg. After conversion the price seems cheap but in reality it is not.

I got a meeting scheduled with the engeneer who developed the concrete on friday, so we have to wait a little.
 
Reeferxbetta
  • #9
I'm actually doing something similar to that, I have a (roughly) 70 gallon all in one tank that I'm likely going to be building a 10-20 gallon sump for, I like the AIO design, but I think it needs just a little bit more space for stuff. My live rock wasn't cheap either, I went with the pricier stuff and a small amount of dry rock (like 8 or 9 pounds, so close to nothing) so my live rock was probably $400-$500 once all said and done. I know absolutely nothing about construction, but I think my main concerns with it would be 1) the risk of it breaking down in saltwater and 2) any chemicals used when making it that aren't necessarily listed as as part of what the concrete is made of (if that makes sense).
 
BRDrew
  • Thread Starter
  • #10
I'm actually doing something similar to that, I have a (roughly) 70 gallon all in one tank that I'm likely going to be building a 10-20 gallon sump for, I like the AIO design, but I think it needs just a little bit more space for stuff. My live rock wasn't cheap either, I went with the pricier stuff and a small amount of dry rock (like 8 or 9 pounds, so close to nothing) so my live rock was probably $400-$500 once all said and done. I know absolutely nothing about construction, but I think my main concerns with it would be 1) the risk of it breaking down in saltwater and 2) any chemicals used when making it that aren't necessarily listed as as part of what the concrete is made of (if that makes sense).

My final cost for the live rock is going to be about 200 BRL initially so I can get a cycle going and will probably add at least another 400 worth later.

I don't think it breaking down on the water is going to be much of a problem but it will need to be deeply cleaned and waterlogged before being put in a tank.

As far as chemical composition goes concrete or rather cement (dont know if the difference works the same way in english) is usually made of a Clincker (which may vary in composition), and some other compounds including gypsum and calcium carbonate. It may or may not have other chemical compounds that can be used as catalysts and such. The only real way to know is by directly asking the manufacturer.
 
Reeferxbetta
  • #11
No idea, I use the words concrete and cement interchangeably, I might be using them wrong too, I really don't know. I knew there was things like gypsum and calcium carbonate, but I know nothing about this kind of stuff, so I wasn't sure if there were some kind of chemicals used in the production of it. I believe calcium carbonate can be added to tanks (I think it's used to change kh or possibly ph, but I'm not 100% sure so I'd look into it further) Anyways, hopefully it doesn't contain anything harmful, and you're able to use it.
 
BRDrew
  • Thread Starter
  • #12
Here concrete defined as the mix between cement and other agglomerates usually rocks and sand.

Calcium carbonate can be used on cyclid tanks if I'm not mistaken to raise both pH and kH.
 
Reeferxbetta
  • #13
Here I believe cement is just an ingredient in concrete used to hold everything together. I thought it was something along those lines, all of my freshwater tanks are pretty simple, so I don't really use anything to modify my parameters, ph is a little high, but always has been, so I just leave it that way.
 
jamie carmichael
  • #14
Reeferxbetta I believe cement is mainly used as a binder for concrete so you're corrrect.
 
BRDrew
  • Thread Starter
  • #15
No idea, I use the words concrete and cement interchangeably, I might be using them wrong too, I really don't know. I knew there was things like gypsum and calcium carbonate, but I know nothing about this kind of stuff, so I wasn't sure if there were some kind of chemicals used in the production of it. I believe calcium carbonate can be added to tanks (I think it's used to change kh or possibly ph, but I'm not 100% sure so I'd look into it further) Anyways, hopefully it doesn't contain anything harmful, and you're able to use it.

Finally an answer! Well.. Kinda.

The concrete has no extraordinary chemical compounds. The components are Calcium Carbonate, Sand (pretty standard river sand, washed), water, cement, a small dosing of aluminum powder and ash. The bacteria that are used to make it aerated is killed during the curing process and since their presence is minimal they do not amoount to much of anithing. The concrete is also burned to make it less reactive.

In theory the aluminum should actually bind with the phosphates but may be toxic in high dosage as explained in theis article:

The sand could also cause silica to be present in the concrete. Effects here:

The concrete itself acording to the manufacturer is extremelly inert but he cannot predict what reaction it would have with high currents and saltwater. The concrete is also incredibly light and I mean really incredibly light at 400kg/cubic meter. Only 40% of the weight of water.

There could be traces of other elements such as iron but its hard to pinpoint what without a lab analisys.

Conclusion: the only real way to know how the concrete would affect a marine envinronment would be to test it out myself. Maybe I can get a small tank and put a small piece of live rock and watch the effects on the water. It should be fairly safe but we can't be 100% sure.
 
AntsRule
  • #16
It might float if its as porous as you said.
 
BRDrew
  • Thread Starter
  • #17
It might float if its as porous as you said.

It actually does float. But it should sink when waterlogged.
 
AntsRule
  • #18
I'm not so sure, wood water logs easy, but I'm not so sure how well concrete will absorb the water. I'm just speculating but I think air bubbles will be trapped.
 
Reeferxbetta
  • #19
I think testing it in a small tank with saltwater is a really good idea. Personally, if I don't know how something will react, I would never put it near my salt tank, there's just too much time and money (and I love my clownfish too much) that's gone into the tank to risk anything, so for that reason I'm definitely not going to immediately say go for it, but definitely test it out in a small tank with just some saltwater before adding it to the display. If you decide to give it a try, let us know how it works out, I'd be very curious to see, as it's actually a pretty creative idea.
 
BRDrew
  • Thread Starter
  • #20
I'm not so sure, wood water logs easy, but I'm not so sure how well concrete will absorb the water. I'm just speculating but I think air bubbles will be trapped.

Water will actually pass through it given time. I believe it will allow about 250 ml of water pass through it every hour but it could be faster. Ive seen concrete that could not be tested for how fast water flows past it bacause it was to fast. The test was directed to external pavements so its not really the most precise but I'm pretty confident it will waterlog.
 
BRDrew
  • Thread Starter
  • #21
I think testing it in a small tank with saltwater is a really good idea. Personally, if I don't know how something will react, I would never put it near my salt tank, there's just too much time and money (and I love my clownfish too much) that's gone into the tank to risk anything, so for that reason I'm definitely not going to immediately say go for it, but definitely test it out in a small tank with just some saltwater before adding it to the display. If you decide to give it a try, let us know how it works out, I'd be very curious to see, as it's actually a pretty creative idea.

I'm getting a small tank to test it out as soon as I can. I believe Ill go with a 5 gallon just for the tests. A small piece of live rock should be able to seed it with bacteria. If the bacteria makes it Ill try some microfauna like copepods and than maybe a small hermit. If everything goes right I might try a fish in there but it might be a while.
 
Reeferxbetta
  • #22
Definitely wouldn't put a fish in the 5 gallon. Even if it's just for a temporary tank, I wouldn't put a fish back and forth between the display tank and the smaller one, would probably stress the fish out quite a bit. I think a hermit crab would be a sufficient test.
 
BRDrew
  • Thread Starter
  • #23
Definitely wouldn't put a fish in the 5 gallon. Even if it's just for a temporary tank, I wouldn't put a fish back and forth between the display tank and the smaller one, would probably stress the fish out quite a bit. I think a hermit crab would be a sufficient test.

Even better. It will save quite a bit of money actually.
 
AntsRule
  • #24
Interesting, ok then best of luck
 

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