@taricha if you see the first picture I posted when I started this thread of the blue sponge frag I started with in the nano 13.5 tank, then see the pics I posted of that tank recently here, you'll see the growth and spread of the sponge throughout the tank. The sponge also reproduced in that tank and blue little ones were popping up out of nowhere.
@Kenneth Wingerter I've also dosed the Substrate Sauce in both tanks at one point, finished a bottle, and reverted back to ProBio. From my understanding, the bac in substrate sauce play a more benthic and denitrifying role, to seed the tank, but I also thought since it has the two strains of rhodo bac then it could be a wider nutritional profile for sponges, although even though I target feed, don't know how bioavailable substrate sauce is compared to the ProBio/YelloSno combo. Thoughts?