said that they have see Old castle wreck tanks by causing all kinds of crazy hair algae. To this point, I have been very luck and only had one very minor case of nuisance algae in the last 5 years. I am very reluctant to use Old Castle. Any thoughts or opinions on this?
Old Castle is the EXACT same sand as what CaribSea calls its Aragamax sand. Both are even mined out of the same quarry in south Florida. I believe that CaribSea is the one that mines it and sells it to other sand distributors that package it up and sell it as play sand under another name.
So, yes, using Old Castle is fine. I wish I could have found it where I live.