I haven't actually purchased, used or even looked at a canister for almost 30 years. Back then the big selling point they pushed was the length of time between cleanings. Is that still the sales pitch?
Of course you can leave a canister for weeks or months without cleaning it, but stop and think what that means compared to a sump with an easily-cleaned initial mechanical stage. If you clean your canister today, seal it up and turn it on, it immediately begins collecting organic debris from your tank. That first bit of fish poop, food or whatever that is sucked up five minutes later is still decomposing in your tank those weeks or months later. Yes, you can mitigate the effects of this by changing water...in fact, you had darned well better do so!
A sump can and should be designed with an easily accessible and convenient initial mechanical filtration stage. The design I typically use allows me to remove and replace the first mechanical stage in about 15 seconds; obviously rinsing off the dirty one adds some time. The crap that squeezes out of the filter pad every day makes me thankful to be removing it instead of allowing my hard-working bacteria to break it down in my aquarium water.
Right about now is when someone points out that they can easily slip a pre-filter sponge over the intake of their canister, performing the same function. Sorry, not quite; a sponge placed there will help...if you actually remove and clean it daily like I do with the sump pre-filter...but be honest with yourself; you're just not gonna do that. Opening the hood, reaching into the water, stirring up the tank, getting chewed on by piranhas and cichlids, splashing and dripping water around...you just won't be willing to do this as often as you would clean an external (i.e. in-the-sump) initial mechanical filter. Let's not even bother mentioning the decreased flow rate that a sponge over the canister intake would cause.
HOB's can be cleaned pretty quickly, but I agree with T Tj203 that they are really not well suited for larger tanks. A big tank needs several of them, which all need to be cleaned frequently to gain the maximum benefit...multiplying the time spent several times over.
Having said that, I have a soft spot in my heart for large sponge filters like the Matten-type. Huge surface area for bacteria, vastly increased maintenance intervals in terms of removing and cleaning (good thing, too...they're big and awkward). But the only way I can be happy with them is by religiously vacuuming the surface of the sponge with each and every water change, in an attempt to remove as much organic material as possible before my BB get their hands on it.
And finally...don't get the idea that I do all this in order to avoid water changes. I am a firm believer in fresh clean water and lots of it. That's really what we are striving to keep healthy: the water. Fish are just hangers-on who do their best to pollute that nice clean H20; don't let them get away with it!
Of course you can leave a canister for weeks or months without cleaning it, but stop and think what that means compared to a sump with an easily-cleaned initial mechanical stage. If you clean your canister today, seal it up and turn it on, it immediately begins collecting organic debris from your tank. That first bit of fish poop, food or whatever that is sucked up five minutes later is still decomposing in your tank those weeks or months later. Yes, you can mitigate the effects of this by changing water...in fact, you had darned well better do so!
A sump can and should be designed with an easily accessible and convenient initial mechanical filtration stage. The design I typically use allows me to remove and replace the first mechanical stage in about 15 seconds; obviously rinsing off the dirty one adds some time. The crap that squeezes out of the filter pad every day makes me thankful to be removing it instead of allowing my hard-working bacteria to break it down in my aquarium water.
Right about now is when someone points out that they can easily slip a pre-filter sponge over the intake of their canister, performing the same function. Sorry, not quite; a sponge placed there will help...if you actually remove and clean it daily like I do with the sump pre-filter...but be honest with yourself; you're just not gonna do that. Opening the hood, reaching into the water, stirring up the tank, getting chewed on by piranhas and cichlids, splashing and dripping water around...you just won't be willing to do this as often as you would clean an external (i.e. in-the-sump) initial mechanical filter. Let's not even bother mentioning the decreased flow rate that a sponge over the canister intake would cause.
HOB's can be cleaned pretty quickly, but I agree with T Tj203 that they are really not well suited for larger tanks. A big tank needs several of them, which all need to be cleaned frequently to gain the maximum benefit...multiplying the time spent several times over.
Having said that, I have a soft spot in my heart for large sponge filters like the Matten-type. Huge surface area for bacteria, vastly increased maintenance intervals in terms of removing and cleaning (good thing, too...they're big and awkward). But the only way I can be happy with them is by religiously vacuuming the surface of the sponge with each and every water change, in an attempt to remove as much organic material as possible before my BB get their hands on it.
And finally...don't get the idea that I do all this in order to avoid water changes. I am a firm believer in fresh clean water and lots of it. That's really what we are striving to keep healthy: the water. Fish are just hangers-on who do their best to pollute that nice clean H20; don't let them get away with it!
