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Discussion Starter · #1 ·
So the Fluval 105 canister filter is rated (according to the box) for up to 25 gallon tanks...does this seem really off to anyone else?

My AC50 only has like maybe 1/4 of the filter media storage capacity and certainly nowhere near the GPH, so why is this behemoth rated for only half the gallonage as my tiny HOB? Is there something I'm missing here?
 

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What it come down to is marketing. How does a company want to place it's products in a particular market?

Most of the time, they want to make you think your getting the ultimate "bang for the buck" so they tend to be "very optimistic" about what it can do. In this case it's how large a tank can you use it on.

Other times, they may have a line of products, and you don't want to compete against your own product, so you rate the product to fit within your product line.

For example with the Fluval 05 series, you have 4 models. Note the pricing points. The 105 is only about $12 less expensive than a 205 and a 305 is only about $17 less than a 405. However, the price gap between a 205 and 305 is about $43.

For only a little bit more you can step up to the next bigger model. Think in terms of what you might hear from a car salesman. (grin)

Obviously a canister with it's larger media capacity is going to be a better choice. This is why you got to read beyond what the manufacture says, and determine if what is printed on the box is good information. It's also why it's worth asking on the forum about any new product your interested in.

The products you mention are good products, but there are also a lot of junk products out there, and products that give substandard performance.
 

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Discussion Starter · #4 ·
The AC50 is rated at 200gph max and the fluval 105 is rated at 125gph. The companies normally rate their filter capacity according to the pump output.
Oh wow, really?! I never knew my tiny HOB had so much output ability! Just assumed that the 105 with it's giant tubing and enormous impeller...

That makes sense I suppose.
 

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Yeah, it's amazing how much energy is used just to pump the water from the canister back into the tank. That's why those little HOB filters can go through so much water for their size.
 

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there is a hugh differance between companies ratings
i have a fluval 405 rated at 340gph and a marine land 360 rated at 360gph
the marine land has double the flow in real world situations
look at the fine print of ehiem rating on their web site
ratings at o head and empty of media
two pumps can have the same rating at o head but be completely different at say 4 ft head
 

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The "head" on most canisters is efectively zero since the water level on the inflow is the same height as the outflow tube.

Just the same, the longer the tubing, the more it resistricts flow.

I have a Fluval 105, and would say that as an only filter, it's about right for a tank in the 10 gallons range.

I would put a 305 on a 25-30 gallon tank.

Don't ever go by the recommended tank size when buying a filter.

I have a Fluval 405 that claims it is enough for a 100 gallon aquarium, but find it much underpowered for the 65 gallon tank I run it on. I run it in parallel with a second canister of slightly lower rating.
 

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''The "head" on most canisters is effectively zero since the water level on the inflow is the same height as the outflow tube''.

if that was the case then why would ehiem state o head then go on to say max head 8.5 ft
if it was o head regardless of canister location because input and output at same height then you could but the canister in the basement and it would still pump somewhat the same flow. not so
look at any canister filter spec and there is a max head
extra tubing length of lets say 2 ft does not account for the difference between say 300 gph and o gph
if you turn a canister filter off it will reach a equilibrium but the pump still has to move the water uphill when on
 
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