Why's a canister better than a HOB?

[JESTERX626]

It's obvious canisters are better, everyones know that. But I never asked, how exactly/technically is it better? From the top of my head I can only think that canisters hold more media and doesnt create surface agitation for those who want to keep co2 in the water for planted tanks.

1. How is the mechanics and filtration process from a canister better than a hob?

2. Do they both filter water the same way or in any other different way?

3. How about a wet/dry? How's that different from a canister/hob and how does the mechanics and filtration process work?

4. What strong points do each of those 3 have?

 

[rumblesushi]

I can't compare to HOB as I've never used one, but eheim canisters compared to internal filters have a few big advantages.

WAY more media, and this is significant. More room in the tank. And a very torquey pump that doesn't clug, allowing longer intervals between cleaning.

 

[Potts050]

It's obvious canisters are better, everyones know that. But I never asked, how exactly/technically is it better? From the top of my head I can only think that canisters hold more media and doesnt create surface agitation for those who want to keep co2 in the water for planted tanks.

1. How is the mechanics and filtration process from a canister better than a hob?

2. Do they both filter water the same way or in any other different way?

3. How about a wet/dry? How's that different from a canister/hob and how does the mechanics and filtration process work?

4. What strong points do each of those 3 have?

A1 Cannisters are usualy equiped with larger prime movers and therefore will filter more gallons per hour if the media is clean. Once the media begins to clog flow rates drop off and the efficiency is severley reduced. This can be off-set by selecting the right media, choosing a more open and porous material, such as crushed staghorn coral or pumice stones. Debris will tend to 'blow' through a Can set up this way but much greater bio filtration will take place since more nutrients and oxygen is available for the beneficial bacteria.

A2 Both solutions provide mechanical filtration. HOB's filter media is more accessible and therefore easier to maintain. For this reason, HOBs are widely accepted a providing a superior effectiveness to power consummed ratio as mechanical filters. Both provide biofiltration although Cans are seen as better at this. The Emperor series HOB with the biowheel however is as good a biofilter solution as most Cans with the advantage of the mechanical filtration effectiveness of a powerful HOB. Cans still have an advantage if you grow snails within the media when filtering tanks that contain fish that will consume them. HOB impellors are not tough enough to withstand snails.

A3 Wet/dry filters have all the advantages of both of the other two types of filters but are more costly. They require more space and consume more energy. They tend to contribute to evaporative losses and heat loss in the tank as well. The offset is they are capable of supporting much larger bioloads and become much more cost effective as the size of the tank increases. Any tanks or aquarium battery systems above 200 gallons should be maintained with this aproach with flow rates in the order of ten times the system volume per hour.

A4 QUO ERATA DEMONSTRATA

 

[rallysman]

I agree with pots except for the 10x flow rate for a wet/dry. I cant understand that apporach. IME 3x gets the job done, even on heavily stocked tanks. I just use more biomedia instead of wasting power on huge pumps.

I have a 265 and a 300 that are both 3x turnover. The fish are healthy, and my nitrites and ammonia are constantly 0.

 

[downset21]

is a wet/dry absolutely neccessary to a tank 220g plus? or even 300gal? or could you put maybe 3 large cannister filters on them? just wondering, i just never used a wet/dry before.

 

[rallysman]

It's not "necessary", but it sure makes it easier (and does a better job IMO)


Wet/drys may look intimidating, but really they are VERY simple once you understand them.

 

[Potts050]

I agree with pots except for the 10x flow rate for a wet/dry. I cant understand that apporach. IME 3x gets the job done, even on heavily stocked tanks. I just use more biomedia instead of wasting power on huge pumps.

I have a 265 and a 300 that are both 3x turnover. The fish are healthy, and my nitrites and ammonia are constantly 0.

I agree that 10x flow rate is not always necessary. Having the capacity to reach that high is useful should you require extra mechanical filtration after say,a particularly messy feeding for example.
High flow rates don't improve biofiltration, only mechanical filtration.
I use a controller that stops flow when my feeder runs and then ramps up to 10x for twenty minutes to capture feces and left over food, then settles down to 2x for the remainder of the day light cycle. I use less power this way and get better filter efficiencies as well.

 

[Potts050]

is a wet/dry absolutely neccessary to a tank 220g plus? or even 300gal? or could you put maybe 3 large cannister filters on them? just wondering, i just never used a wet/dry before.

Three cans will work and offers some advantage in that you can take one out of service for major cleaning without impacting the biofiltration capacity of your system. The argument is that a wet/dry sump combination would cost less and consume less power than three good Cans.

 

[rallysman]

I agree that 10x flow rate is not always necessary. Having the capacity to reach that high is useful should you require extra mechanical filtration after say,a particularly messy feeding for example.
High flow rates don't improve biofiltration, only mechanical filtration.
I use a controller that stops flow when my feeder runs and then ramps up to 10x for twenty minutes to capture feces and left over food, then settles down to 2x for the remainder of the day light cycle. I use less power this way and get better filter efficiencies as well.

That's cool

 

[downset21]

It's not "necessary", but it sure makes it easier (and does a better job IMO)


Wet/drys may look intimidating, but really they are VERY simple once you understand them.

read my mind... my only reason for possibly using 3 cannisters that way is that I dont know much about wet/drys and can only foresee a disaster with them... i've got some studying to do now.