Can crushed oyster shell be used as a substrate?

[Michael]

Originally Posted by reef_raf

Again, I wouldn't, but some people do. When I bought my 75, the guy had oyster shell as a substrate. Even the fish had cyano growing on them!! Seriously, there was more cyano in that tank than I'd ever seen and he said it started as soon as he started the tank and got worse as time went by.
I can see no reason to use oyster shell; if you can't afford or don't want to use aragonite sand, crushed coral or silica sand are both viable low-cost alternatives. Glass beads have even been used successfully.

Thanks for the insight. The only reason I was thinking of using oyster shell was because a huge bag was 25$ . The aragonite sand would have been over 100$ for the same amount.
Currently, I do have aragonite sand in my aquarium, but need more.
And I definitely don't want cyano again!!

Guess I'll pick up some aragonite sand.

Michael