adding this:
if you disconnected that filter, and never put it back, no harm would come and no change. you need that surface area in freshwater setups, not in reefing.
the worst thing you can do is half clean it, turn it on, and pump waste into your system. that filter is a liability, not a help (if you get a power outage while at work for 5 hours, all its bac crash, then power on pumps it into your tank)
the safest thing you could possibly do is remove all media, run the canister empty, and use it only for flow.
I'm adding this post/thread to my updated cycling science 2023 thread: aka new rules opposite of what everyone was taught using the old methodology. the only time a substrate-packed canister filter or HOB filter is useful is when a display aquarium lacks the surface area needed to oxidize ammonia waste from inhabitants. no reef display ever meets that condition, none of them. it would require a system with no rocks to pose that risk, I literally don't know a single rockless reef tank on the site.
the irony is that full complete cleaning is safe, or taking it fully offline is safe, but any partial cleaning is a total risk to your reef. = ironic