I recently installed a 15 gal
fuge to my system. I used mineral mud as a substrate and covered it with 1/2 to 3/4" crushed coral as per the directions on the mud container.After two weeks, I'm seeing bubbles between the mud and the sand through the glass and tiny bubbles keep coming out of the sand everywhere. I placed a snail from the main in it to lick the glass and it climbed right out of the water and sat there most of the day. My question is, could the sand layer on top of the mud be almost choking the mud and turning it toxic? and if so would it be better to lose the sand or at least most of it to let the mud breathe so to speak? I have never had a snail completly leave the water before and it has me concerned. Sorry this got so long. Thanks Jamie.