# Concrete in a terrarium / vivarium



## fuzzybackpack (Jul 15, 2009)

Does anyone know what kind of concrete you can use to make a waterfall or background in a vivarium?

I've heard concrete leaks out substances that are bad for the plants and darts?

How do you make the concrete "viv safe"/ keep it from leaking the bad substances before you put it in?

Different ways to seal the concrete?

How do you even build a concrete background/waterfall?

Any tips or suggestions on putting concrete in a viv are very helpful. I've only been able to find bits of info about how to incorporate concrete into a viv.
ANYTHING HELPS


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## jon (Mar 12, 2008)

I hate to be "that guy", but the search function is going to be your best bet here. There are multiple threads on the subject. Everything from which ones to use, how to cure it, how to build the forms, etc. There are a few different techniques, and I don't think anyone is going to repost their know-how in reply to your question.


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## Petersi (Jan 31, 2008)

search "rock wall"


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## David Brahms (Oct 31, 2009)

fuzzybackpack said:


> Does anyone know what kind of concrete you can use to make a waterfall or background in a vivarium?
> 
> I've heard concrete leaks out substances that are bad for the plants and darts?
> 
> ...



I will answer some of these for you so that folks may find the info useful. Anyway...hope this helps.

I owned a small company that made artificial rocks for the marine aquarium trade. The hobbies (Darts and reefs) do share many of the same qualities and the concerns of using cement or concrete are similar. 

1) Fresh cement will create calcium hydroxide as a byproduct while curing. Calcium hydroxide is very high in pH and this is what is a concern. You can use regular cement without worrying if you give it enough time to fully cure and allow the calcium hydroxide to convert to calcium carbonate. This is done by keeping the cement damp and exposed to CO2 over time. The length of time varies greatly depending on temps, porosity of the rock, and humidity levels. Thin layers of cement or concrete will cure faster than thick "rocks". Generally 6-8 weeks and longer is needed for curing....again this varies greatly.

2) There is a "trick" that will allow portland cement (the main binding ingredient in concrete)to cure faster than if it was used alone in your rock mix. Silica Fume (or micro silica) is a additive for concrete/cement that is used to strengthen the material and to be used in marine environments (coral reef restoration groups use it for it's pH lowering abilities...search Reef Balls as an example). One of the neat properties of Micro-Silica is that it causes the cement to form a different form of calcium during the set and cure instead of calcium hydroxide. As a result the pH of rocks made with silica fume are usually lower than straight portland cements rocks initially and cure at a much faster rate since much less calcium hydroxide is produced in the process. Look to your local cement distributors to get Silica Fume. The brand I used was Eucon MSA and cost about $15.00 for a 25# bag. Only 5% by weight is needed to add to your cement mix for the desired outcome.

3) Once cured cement rocks/walls do not need to be sealed. Less chemicals used in the Viv the better IMO.


Hope this helps....


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