my roommate and i were doing a final check on a tank we've had up for 3 weeks before sending the check for the shipping of our frogs and my roommate noticed slime covering the top of the log we use for a waterfall feature. she took it out and rinsed it off with hot water and we noticed it all down the side and in the rocks along the bottom of the tank were the log rests. is that normal? is it safe for the frogs? they are thumbnail darts.