# Home made background ...."dumb question?"



## TylersDad (Aug 10, 2008)

Hello, new to this site, found it googling DIY aquariums and I am now a member and love it.
I been into the hobby for 20 years almost, and I never thought of making fake rocks out of styrophome until now.
However I just carved, glued and painted, and put it on the back outside the aquarium.

I love all your pics of the in tank ones and read all the directions.
My , (maybe stupid question), is; cant the cement mix or concrete be bad for the fish?
What other ingredients are involved to make it safe, or could I buy just any concrete mix, let it dry and enjoy?


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## trigger (Sep 6, 2002)

I guess there could be cement mixes around that have several additions to make it stronger or faster curing or whatever. As far as I know the portland mixes are as pure as they get and can be used without problems. Since I'm from europe and we have completely different brands here I can not help you much more.


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## TylersDad (Aug 10, 2008)

Thanks, I feel safer about the cement I bought then.
Id been waiting for a reply before I applied it.
Appreciate the help.


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## Eb0la11 (Feb 29, 2008)

Its safe after you let it leach out its high alkaline properties in a seperate tub of water.

Test the parameters of normal tap water, record them then throw the concreteted rock into a tub fully submerged and test the parameters again. They will be high alkalinity. You'll have to let it soak for a couple weeks changing the water every other day until the water parameters return to normal, then its safe.

This is of course after a normal 2 day cure at minimum outside the tank where you are spritzing the concrete to keep it wet so as to prevent it from cracking and flaking.


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## Mcdaphnia (Dec 16, 2003)

Eb0la11 said:


> Its safe after you let it leach out its high alkaline properties in a seperate tub of water.
> 
> Test the parameters of normal tap water, record them then throw the concreteted rock into a tub fully submerged and test the parameters again. They will be high alkalinity. You'll have to let it soak for a couple weeks changing the water every other day until the water parameters return to normal, then its safe.
> 
> This is of course after a normal 2 day cure at minimum outside the tank where you are spritzing the concrete to keep it wet so as to prevent it from cracking and flaking.


Oops! "2 day cure" is a bit quicker than the recommended 28 day cure. If you cure the cement coating the way the manufacturer suggests for maximum strength, you will have very little excess alkalinity.


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## trigger (Sep 6, 2002)

Eb0la11 said:


> This is of course after a normal 2 day cure at minimum outside the tank where you are spritzing the concrete to keep it wet so as to prevent it from cracking and flaking.


Like mentioned, 2 days is a bit on the short side... I kept my background wet for two weeks before putting it in the tank.


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## TylersDad (Aug 10, 2008)

Thanks for all the advise, It's my first attempt at this and after I figure out how to upload my camera, I'll add some pics.
I carved it into one piece already and added a bunch of hidden coves and caves.
I didnt think about it, but I dont have any spare tanks it will fit in.
I'll problably have to cut it into two pieces without loosing any of the design and soak it in a big rubbermade with a power head.


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## TylersDad (Aug 10, 2008)

Thanks for all the advise, It's my first attempt at this and after I figure out how to upload my camera, I'll add some pics.
I carved it into one piece already and added a bunch of hidden coves and caves.
I didnt think about it, but I dont have any spare tanks it will fit in.
I'll problably have to cut it into two pieces without loosing any of the design and soak it in a big rubbermade with a power head.


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## Eb0la11 (Feb 29, 2008)

Concrete actually cures best under water. Perhaps 2 days is too ealry to submerge it but once its hard putting in the water to cure and to rmeove the alkalinity will ensure a solid cure.

I didnt mean to put it in the fish tank after 2 days. Not sure how that came across.


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## Eb0la11 (Feb 29, 2008)

I'm just about to concrete mine and thats what others had told me anyway.

Another quick question, what concrete should I get? I cant find quickcrete quickwall at my LHS. Do I need some kind of wet lock or whatever its called?


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## TylersDad (Aug 10, 2008)

Just wondering, I like how this is coming out for my frontosa tank, and I was wondering if a concrete background would be safe in a saltwater tank, after curing it and removing the hardness of course.


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