coral and tank problems

can u share your water change routine? was it from the same source? has this happened on previous water changes? if its occured directly after a WC, then i guess its related.
 
It's posted earlier - RO water - approx. 20% change - SG, ph and temp all matched. Even w/ RO I still use a de-chlor. to play safe. Any suggestions for the coral or the micro bubbles?
 
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