Sand bed indecision...

[jostafew]

Deja-vu hahaha, a very similar question was just posted a couple days ago. Here's an abbreviated version of my previous reply; it depends....

What livestock do you intend to keep? LPS and softies, SPS, sand-sifting animals.... Fish and flow willd determine the requirements of the sand-bend. For eg. I have a canary wrasse which requires atleast 2" of fine sand to burrow into each night. I have sugar sand in my tank which does get blown around, but I accept that limitation and know that my tank will probably never be a killer SPS tank because I have to limit the flow to prevent a sand-storm.

As for the DSB problems, that shouldn't apply to a healthy DSB with the appropriate livestock slowly turning over the sand bed. Pods, worms, snails, and fishes turning over the upper surface should prevent any buildup of toxic gases. Nitrate buildup? Only time I heard of that was with people using crushed coral or very course gravel which collects detritus and allows nitrates to buildup. In order to get the benefits of a true DSB (oxygen deprived zone) you need fairly fine sand.

So think about the livestock you want to keep, if fine sand doesn't jive in the DT, run a DSB in the refugium or an external DSB. If anything I'd say fuge / external is the safest place because it can be easily serviced if needed, then just put whatever suits your livestock and your taste (visually) in the DT.

I'm relatively green at reefing, had a tank for just about 2 years, but I like you have done tons of reading on the matter. Good luck!