Can't I use the DSB from the 150 and then add the coral to the top?
Don't add crushed coral to the top of the sand. I would only put in an inch or so of sand to start. Seems to be quite a little controversy around DSB
's and OTS (old tank syndrome) these days. To be on the safe side, I would hold off on putting in the full 4" of sand. Putting it in the refugium instead may be prudent so it can be removed/changed in a few years if DSB
's are shown to be related to OTS. I'm not convinced yet but I would play it safe in a new setup.