Thanks! Ill keep an eye on the pH, and run a test tonight too.
Oh, and I put the carbon bag in the fluval filter after putting the petrified wood in, just in case there's more than just a trace of minerals on there - I did scrub them all before putting them in though (my son actually helped with that too, thanks!) so no strange Arizona dirt should be floating around there, but you never know. I'll keep the carbon in there for a month then toss it if everything looks a-ok.
Last edited by Jahn; 05-02-2013 at 02:47 PM.
Reason: Carbon bag added.