Substrate Sauce is made with a measured excess of phosphate (from dipotassium phosphate). This is meant to support microbial growth during cycling, as Sauce is meant to be a cycling product. However, I've seen people use it in established tanks as a means of replenishing depleted phosphate levels. I suppose this is the intention of some individuals who are elevating phosphate as part of their strategy for battling dinos; in that case you get a boost from that, as well as an extra bacterial species to throw at the dinos (Sauce contains two PNSB species, Rhodopseudomonas palustris and Rhodospirillum rubrum, whereas ProBio just contains R. palustris).