I've done test using/not using PS and using ADA AS.
I used 8 small tanks, I could not see a difference after 8 months.
I suppose if you do not dose anything to the water column, it might help.
But whether you add it to the sediment or and the water column, as long as it's there, everything is fine.
But, this implies it's NOT needed and is a lot more than a month or 2 worth of KNO3/KH2PO4.
After that, it's not more than pumice that mixes and looks ugly.
NO3 is what's mostly in it. And NO3 is extremely mobile meaning it's going to slowly leach. So you may as well add KNO3, little by little for 50 cents and then by pass the addition altogether.