# Expanding foam



## Derek113 (24 May 2016)

Im planning a small paludarium build.
I was going to create some depth using expanding foam, however, how does this hold up against constant water exposure?

Any thoughts?


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## Finn (25 May 2016)

It depends on the product used, the stuff intended for interior use decomposes over time when in contact with water and requires sealing, but there are some exterior ones that suggest water resistance.  I hear grout is a popular option for sealing terrarium and paludarium elements which should make the thing water stable so I would simply grout everything no matter which product I chose to be on the safe side. If you're still in doubt though read the material descriptions and field of use of the products you're intending on using.


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## ian_m (25 May 2016)

Please read the material safety data sheets first, as all the ones for expanding foam I have read state....





























However is appears once set and left for a suitable length of time it is not biodegradable and not bioaccumulating, thus appears to be inert.


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## Derek113 (25 May 2016)

ian_m said:


> Please read the material safety data sheets first, as all the ones for expanding foam I have read state....
> 
> View attachment 85599
> 
> ...



Useful information. 

My fead is that it could leak chemicals into the water over time. To be safe i will use a cement to cover it.

Thanks


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## idris (4 Jun 2016)

As Ian says, if disolved you might need to concern yourself, but probably not otherwise. 
The same considerations would be needed for "cement". If you coat it with a small layer of Miliput you should be safe.

Could you not use rocks rather than polystyrene? Again they can be stuck together with either Miliput, or just aquarium safe caulk.


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## Derek113 (4 Jun 2016)

I have decided to use polystyrene sheets/blocks as it eliminates any chemical leaks.


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