meh...IMO, miracle mud is no miracle....
I wish I had the report of when someone put it through a gas spectrometer...it was laiden with massive heavy metals and wasnt from the ocean whatsoever, in fact, it had terrestrial debris from trees and plants mixed in with it as well... when it first came out I sold and ran this product for years and have spoken with leng cy at length about the proper ways to employ this product...
my best advice based upon dealing with many tanks that employed this method is to stay away from this product.
use rubble live rock for a media in your refugium, there will be more surface area for pods and mysids to hide in and propagate, as well as it's massively easier to clean out the detritus that settles in your fuge with rock rubble.
if your macroalgae needs iron or iodine, then dose those items, to me that makes better sense than to use something that leaches metals into your system 24/7.