where did you put that sponge bag in your system?
I didn't, as i said in the video i had already seeded my tank, and i didn't want to over do it. That was just a demontration on how to do it. I would put it in the over flow like i did before. This way, it goes first into the sump where sponge grow usually in the dark, remember we're talking about individual celles here, that will travel all over your system, so some will go in your skimmer some in the return, and populate your tank. I have some already growing in dark places but don't over do it either once is enough. They may not be the same colors either. And that i can't explain. I left that bag for about 24 hours and then took it out and dump the sponge matter clean my bag. and reused it for the video you saw.
I found some of that sponge under some of my rock structure and right between my GSP , its growing in there and don't bother the coral, it follows the skin of the coral, because the GSP is right in the jet of the powerhead and sponges likes that. Hope that helps.