It seems that the canister haters usually use the "nitrate factory" for their argument against them.
So how do you explain the numerous threads about high nitrates even though a sump is being used? Seems like the "nitrate factory" argument is quite flawed since sumps do not appear to be the "cure" for high nitrates.
This is a terrible way of looking at it and 100% a logical fallacy. A sump in itself doesn't have anything and the amount of nitrates has a lot to do with the bioload.
The reason I'll never use a canister filter again is because they are a pain in the butt to maintain. There is no room for any other equipment, it's just the one filter.
Can you put your heaters in the canister? I have 2 300 watt heaters that are like 2 feet long. A canister filter isn't going to provide room for that, or any heater. So now you've got your heaters in the display tank.
Can you run a UV filter in your canister? Not really. It doesn't remove nitrates, but it does kill algae blooms and parasiets.
Can you run a skimmer in your canister? Nope. This is a piece of equipment that does remove organics and helps with nitrates.
Can you run a refigium in your canister? Nope. This is a part of a sump that will use nitrates and reduces the amount of them.
Can you run your dosing lines into your canister? Nope.
So why in the world would I EVER want a canister filter? It doesn't provide a SINGLE thing that's superior to a sump with equipment. Even if you get a canister with more features like UV, it's probably not even a good UV light for the job etc.
Call me a "hater" if you want, but using a canister filter is a joke in comparison. I haven't even hit on all the reasons why a sump is better.