A lot of times a certain species will multiply out of control when first adding liverock to a new tank.
With the high numbers they will exhaust their resources and inevitably crash.
They will then reach an equilibrium with a stable population based on your tank. This can take over a month. Its just one part out of the many of your tank stabilizing or 'cycling'.
When i first started i added really good liverock from coralreef petstore. Ton of sponges, coraline, dusters, pods, ect.
For the first month i had these really tiny white/clear pods everywhere. I remember putting my arm in the tank , and when i took it out it would ich horribly until i washed it with tap water. They covered the rocks, glass, my arm, ect. After a month i still saw them, but there were alot less. They now have a sustainable population.
Just give it time, your tank will stabilize.