Unless instruction on your brand's label says otherwise, pH anything going into substrate to 6.5. Don't change so many things in 1 week (from comment of diary). The pH alone could fix most of what you were seeing. Treat it more like soil. Wait for the color to change on top to a light brown but only top layer is enough. It'll repel water intially, but just put a light amount down first and then it'll water as normal after that soaks into top layer.