Wow peasly1
Is that weird or what ...
Are the sandmound lumps in the exact same places as before - before you leveled them out ? Or are they in new spots on your sandbed ?
Still curious as to what these are and what is causing them to form.
As far as a sandbed "exploding" I would imagine you are referring to the possible formation of hydrogen sulfide gas in the deepest most oxygen poor levels of the sandbed.
It's true that this gas can indeed form, but I've never heard of the entire sandbed exploding.
IMO it's not a myth - just a misconception.
For those that support and believe in the benefits of using a DSB - many have followed the advise and methods of Ronald L. Shimek, Ph. D.
I've included a link to an article he wrote, describing deep sandbeds in general, and towards the bottom of the page, he describes his feelings about hydrogen sulfide gas.
If it appears in your tank, you'll possibly see it as very dark - black patches that form between the glass and the lower portions of the sandbed. They are not uncommon at all, and these patches may be present in a number of different locations at very deep levels ( not just along the glass/sand interface. )
I'll let others reply - I'm sure there are a lot of various opinions on this topic.
HTH
<a href="http://rshimek.com/reef/sediment.htm" target="_blank">http://rshimek.com/reef/sediment.htm</a>
