I have seen and read a few threads regarding the deep sand bed, I like the concept of that. Are you going to place light defuser under the LR with the deep sand?
I am deciding on what sand (color and grade) I need to buy for my tank. I am tossing out my sand when I break my tank down.
DSB do not really work in nanos. Nanos have very
little water volume, and as much as possible is needed. To be effective, DSBs need to be 4" or greater, and in a nano, not only does this not look good, but takes way too much water volume away from the system.
You'd be much better off to invest in a good skimmer and, if you still have any nitrate or phosphate issues, look into dosing a carbon source, such as vodka, sugar, or vinegar.
The DSB that I made is simply to cycle sand. I put all my sand for my big tank into my QT tank that is already set up and dumped a teaspoon of sugar into it to get the cycle over with in a couple of days since I was expecting to pick up my new tank tomorrow (now will be next week). I only posted the thread here as a joke since people are always bickering about how DSBs aren't feasible in a nano.
As for sand choice, black sand is awesome, your corals will stand out much more in comparison to white sand. Most black sand, unfortunately, is sugar-fine, and can be an issue in high-flow systems. I hope it won't be a big issue in my big tank, I've got three MP10s I'm putting on it.