I am a month into my first AIO saltwater 32 gallon biocube--2 clowns, sally lightfoot crab, 3 snails, and a tiger conch. Recently, I noticed tiny metallic-looking bubbles rising from the substrate and on the live rock. Is this nitrogen? They are gone now, but I had never seen those before--really cool through a magnifier. But just want to be sure they are not dangerous. thanks.