Polystyrene - ok to use?

[Conger]

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.

 

[Henry]

Yep.

 

[Edvet]

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

 

[OllieNZ]

Or egg crate like the reefers use

 

[Edvet]

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

 

[Rich Jackson]

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