Ok so forgive me if I’m repeating something another old school reefer already said. But this is not the first time the hobby has had this problem and it’s not the first time it solved it either. However solving it still comes with the same risks it did in 1995-2000.
So the first time we struggled with this was the same era that we tried switching over to aragacrete rock. For those unfamiliar it was basically home made rock from Portland concrete, rock salt, and crushed coral or oyster shell. You had to cure it a ton before you could use it. But before we all roll our eyes it’s basically the same thing we are doing with all of he concrete based artificial reef rock today. …and no surprise we are having the same issues. Marco rock is nearly the same for the same reason. It is void of life.
it’s not as easy as adding a few types of bacteria. Even if we knew the 7 most important -the inter relationships between them is extremely complex and involves other microbes and micro fauna as well. I feel like microbial plaques simply get no attention or due credit in the reefing community. So I highly doubt we are going to nail it with a bottle of bac.
But as mentioned earlier this is already a problem we solved 25+ years ago. GARF was the largest advocate of aragacrete and also sold “garf grunge.” It was basically one of the best live rock activators the reef community ever had IMO. People complained about it because it looked terrible and often had hair or whatever was at the bottom of some super old reef tanks. It’s still sold. It has sponges and pods and microscopic worms and fungi and and and…. But it also contained the pests of a super old reef tank. So there are trade offs. But if you can find a trusted friends tank a cup of sand, a bunch of detritus in a turkey baster and handful of rock rubble can go a long way. Like frags you’re just seeding the tank.
And before bagging on garf for making a product that has pests please consider they era. We did not strive to start a tank with a sterile environment, we welcomed aptasia and flatworms as biodiversity that were kept in check (mostly not well) by predation. But that was what we did -for better or worse (mostly for worse for my corals and better for my fish).