# Polystyrene - ok to use?



## Conger (27 Nov 2013)

Ok, sorry - dumb question - the answer is probably on loads of threads elsewhere if I have a trawl...

If I'm placing some very heavy rocks in the aquarium, is it safe to use polystyrene under them to safeguard the glass? Or some chopped up yoga mat? Don't want to rely on substrate as the rocks are 10-12kg..! Worried about leaching nasties into the water.


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## Henry (28 Nov 2013)

Yep.


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## Edvet (28 Nov 2013)

Polystyrene is no problemo, don't know about yoga mats.


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## OllieNZ (28 Nov 2013)

Or egg crate like the reefers use


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## Edvet (28 Nov 2013)

Why oh why doe we have crapy cardboard egg crates..........


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## Rich Jackson (28 Nov 2013)

I wouldn't worry to much.  I had 60kg of rock sitting on crushed coral sand in my reef tank with no issues.


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