Deep Sand Bed vs. Shallow Sand Bed

Well, if it's already there, just make it work well. One of the most common causes of failures of DSB's is lack of bioturbation. Get a sandstirrer package. In the day, Inland Aquatics and Indo-Pacific Sea Farms sold packages to keep that sand moving. I'm sure they probably still sell them. Nassarius and cerith snails get in there and move things around too.

 

my orange spot diamond goby does a great job of stirring the sand!

something else that I should mention that I've never seen anyone mention before is that I have algae growing under the sand... the light on my fuge radiates enough light to cause algae to grow underneath the sandbed... surely this is not a truly anoxic layer then?

 

Actually it is only growing between the glass and the sand from ambient light or reflected light from your fuge. I have it too and it gets irritating at times but the ceriths do a pretty good job of gettin in there and cleanin up.

 

It's likely to be a very small aerobic area, and an anaerobic layer as soon as 1/8" from it; the amount of oxygen a small amount of algae that's a film on the glass can produce is tiny.

 

I think deep sand beds are good for stability but very very bad if you disturb a part that hasn't been disturbed for a while. It happened to me I got huge waves of cyano and cessation of coral growth. Also I think It will cause problems many years in the future even without being disturbed.