if you can't est. if a rock type is tank safe...next time you do a pwc
, just use the tank water you're pulling out, fill a five gallon bucket and place a decent sized rock in there...all you have to do is simply test the bucket water every day/2 days...if your ph or anything spikes thru the roof...you'll know its not tank safe.
oh and ps. did a pwc
last night...fish are doing great! I think they are more comfortable with this new design..