are concrete blocks reef safe?

[Reefski's]

i have used a bunch of these in my system for mounting the LR on?

i have had persistent problems with sps corals dying for no apparent reason.

a friend suggested that maybe the concrete blocks are toxic.

i know many people make their own rock from concrete. are the blocks that different?

as some of you may know i am about to redo my system. should i remove all of these when i do?

 

[hal000]

no they are not reef safe & god bless all the little critters in your system!

 

[Diver Dan SD]

They are safe after they cure in freshwater (you may be able to use SW though; I'm not sure) for a couple months. What happens is, all of the chemicals and compounds used to make the concrete are leached into the water. Some of these chemicals, lime etc., could be pretty harmful to marine life killing your pH and other crucial balances. After that they are just like LR minus the pourus structure that makes LR so great.

 

[5h3rW1N]

i would cure them as your would cure live rock. cure it for 2-3 months in a running vat tank.

 

[Reefski's]

they have been in my system now for about 18 months.

 

[darkdruid]

You need to cure the blocks just like MMLR. It's basically the same thing, but after 18 months, they're cured and shouldn't be a problem.

 

[EllieSuz]

I wouldn't count on harmful elements being "cured" out of your system. Why not get rid of them and build some nice frag shelves out of egg crate?

 

[Ding2daDong]

Come on people this is Reefski! Obviously the rock has been cured. I don't know the answer but hopefully someone can chime in with some useful information.

-Matthew

 

[CleveYank]

Alot of building materials are coming in from China now. Normally, I'd never attribute 3 to 6 month aged blocks to issues. But if they came from China there's no telling what gravel source and what's in them that they used to make them. I'd call the store and double check the true source of the block. If it's domestic the other idea would be track down and contact the block foundry and inquire what's in them. If they're China import? I'd use them elsewhere than in my reef setup.

Many years ago one of the European reef duos had a text, in which I read about a couple public aquariums using acid cured cinder blocks as the foundations for some of their massive displays with no ill impacts. But knowing what's in it next to a proper cure is half the battle.

 

[JamesJR]

This isn't really that relevant but I doubt the blocks came from China. The US only imports a fraction of the cement that is used on an annual basis and the cement industry tends to be very regional in nature as importing and transporting cement is so cost prohibitive. Especially being that the US has such an abundance and easy access to the minerals to required to make the clinker and the portland cement.

 

[chilwil84]

we were importing sheetrock from china during the peak of the construction boom we could have easily been importing concrete products during the same time period.

 

[CleveYank]

we were importing sheetrock from china during the peak of the construction boom we could have easily been importing concrete products during the same time period.

I saw the cardboard labels made in China on block on a couple pallets at Home Depot. Which I asked about, which salesman said yep made in China.

 

[scaryperson27]

Cure it in fresh RO water. RO water strips chemicals pretty good. I would do that along with water changes. You could also try vinegar but I don't know how that would work.

 

[TurboGuru]

I've used several of the 2" thick block caps to mount my aquascape on as a level base. I have not noticed any problems... so far. My tank is SPS dominant and grows very well. I currently have an outbreak of diatoms on my sandbed, but that is from a nutrient problem I believe I have fixed and it looks to be slowly going away. (crosses fingers.)

HTH,
Joe

Here is a recent pic.

 

[Reefski's]

I've used several of the 2" thick block caps to mount my aquascape on as a level base. I have not noticed any problems... so far. My tank is SPS dominant and grows very well. I currently have an outbreak of diatoms on my sandbed, but that is from a nutrient problem I believe I have fixed and it looks to be slowly going away. (crosses fingers.)

HTH,
Joe

Here is a recent pic.

nice tank.

thanks for the feedback all!

i too used the caps.

taking them out will be a pain and will stir up the sand that i want to take out too

thanks for sharing your experience. how long has your tank been set up?

most of the world's cement comes from China.
http://en.wikipedia.org/wiki/List_of_countries_by_cement_production

i used the blocks in my old tank that successfully grew SPS corals for a couple of years until i set up the current tank. the old blocks were blocks not caps and likely were made somewhere else than the current caps that i have in the system now.

taking them out will be a pain but then i won't have to worry about that anymore.

how best to remove them without stirring up trouble?

anyone else have them in their system?

 

[hal000]

Come on people this is Reefski! Obviously the rock has been cured. I don't know the answer but hopefully someone can chime in with some useful information.

-Matthew

reefski or no reefski, going tru his post it seems like he has been having a problem since he set this tank up, IMO it is the block!

most of us have said no they are not reef safe, cured or not they will most likly leech somthing into the tank! why take the chance!

so with this said maybe u can chime in with some useful info somtime, instead of running your fingers making it like any of us who replied do not have a clue!

 

[TurboGuru]

nice tank.

thanks for the feedback all!

i too used the caps.

taking them out will be a pain and will stir up the sand that i want to take out too

thanks for sharing your experience. how long has your tank been set up?

most of the world's cement comes from China.
http://en.wikipedia.org/wiki/List_of_countries_by_cement_production

i used the blocks in my old tank that successfully grew SPS corals for a couple of years until i set up the current tank. the old blocks were blocks not caps and likely were made somewhere else than the current caps that i have in the system now.

taking them out will be a pain but then i won't have to worry about that anymore.

how best to remove them without stirring up trouble?

anyone else have them in their system?

I'm not sure how to remove them. My removal, should I have to break the tank down, will consist of removing all of the rock first and then digging out the caps from the sandbed. I believe that if I have to remove them, the system is in serious trouble anyway, and upsetting the sand is the least of my problems.

The tank in the pic has been up since Nov, 1, 2009.

 

[chilwil84]

turbo guru nice tank. the thing about concrete in florida is that they use agrigate based sand because its there , unlike most places that use silica sand.

trusting wiki is like trusting a blog. while some products at big box chains might be from china most concrete blocks are made within a 100 miles of where you buy them.