Anyone else keep this snail in their tank? Just got 6 from snailshop today and they start working immediately when I threw them in the water. I know they do burrow into the substrate and keep turning the substrate over and it helps to prevent H2S build up in anaerobic spaces. Just wondering does anyone knows how deep they burrow themselve? I've got quite a thick substrate level (2.5 inches at the front and 4.5 inches at the back!) and would like to them to burrow deep enough to help me prevent that problem from happening in the first place. So far they don't see to go any deeper than 1 cm off the surface.