Sorry to hear about your losses and your tank issues
Cloudy may mean equipment failure or equipment back up (clogged skimmer?)
I hate canisters for SW setups as I'm not sure of their overall effectiveness vs risks.
Although some have had (are having) success with HOB fuges, I've had poor luck with them as they need continuous cleaning otherwise they can become a "messy" proposition. Sumps perform better than HOB refugiums in my experience. Cleaner, neater and easier to maintain
Have you dosed beyond regular parameters ? Any of the occupants or CUC missing in action ? (any decaying matter can cause potential issues). Perhaps more flow is needed ? I can loan you an MP10 if you want to experiment
Having said all of this, it may come down to the fact that you may never be sure of the cause. This hobby can be a beautiful siren or a cruel mistress
Best wishes