Water change is never a bad idea, as long as the water is the same temp & parameters.
Some anemonies will "cough" after a feeding, don't know if condies do but its possible. This might be you nitrates.
For a reef tank, canister/wet-dry/power filters are generally frownd upon. Canisters get clogged really fast in an established reef, and wet-dry filters are nitrate factories. Generally, the best is live rock. If you have a sump, some chaetomorpha macroalgae will assist the live rock in nitrate removal. If the water seems to cloudy, you can run a course filter sock, but a protein skimmer and carbon should keep the water clear. (And, efficient mechanical filtration cleans out "good" critters.)