why not just deep clean the system, far more effective and cheaper.
a deep clean is not your normal cleaning, its 10x beyond what you're expecting, but we have about a thousand logged already including hundreds of 20 gallon reefs. the chance it beats dinos is about 90%, higher than any other method.
it takes three hours to deep clean a 20 the right way, from our logged action threads.
install your uv after the rip clean, not before, for ultimate action.
-is it harmful-
no, the deep cleaning is a tank relocation thread. we deep clean to avoid recycles on moved tanks, yours is simply staying in place but getting the same workover.
deep cleaning doesn't become bad or destabilizing in an in-place nano, and then all good for when its time to move.
if the aquarium is of such size that getting it cleaned is easy, then its always good.