Yes, I agree with dnsfl, I also have same observations. When I remove my miracle mud and clean up the sump, big impact to the bio filtration and suddenly sps that were growing well started stn, and acans bleaching, sps turn brown. Cynobacteria appears, hair algae grew fast. All happen within 5 days period.
Put back new miracle mud, everything stablize and sps colours slowly coming back. Never underestimate what 5lbs of sand/mud can do to your tank. Always make small quantity removal at a time.