Thanks for all the response guys. I'm going back today and try and get it again, had no idea about the white stuff leaking po4 into the water though. I wonder if it's proven or just speculated, might just chance it. My first diy frag rack is entirely covered in coraline but it was black plastic so hopefully this new one will just get covered quickly. On the other hand the racks on blackrock reef look very attractive, and for the price, not bad.