substrate

[Weeble]

ok im sure you've all seen this topic before , but my question to you is about oyster shells...alot of people use it in their DIY rock and so i was wondering if it would be ok to use with a mix of sand as a substrate?? anybody using or have any ideas? ive heard it may create a phosphorus problem?

Thanks
Craig

[Mr.Lloyd]

I use nothing but aragonite.