How are filters rated?

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crashinc25

crashinc25

Candiru
MFK Member
Jun 27, 2007
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Yucaipa, CA
In another post, I asked about filter media ordering. I was asked the reason and I replied explaining that I would rather use a canister measuring 13" x 11" rather than 8 1/4" x 15". I just realized I have no idea why that would matter?
Can any mathematician or anyone really tell me what exactly deems a filter rated for a certain tank size? Is it internal size? Surface area? Flow rate?
Thanks

Rob
 
It's a combo of things. Flow, amount of media it holds, type of media, etc.
 
Rating a filter is an overall personal choice. Usually the manufacturer rates a filter in terms of gallons per hr (gph) and/or states that the filter is suited for tanks up to X amount of gallons. My personal choice on that matter is to go with some overkill. Example: If a filter is rated for up to a 45 gallon tank, chances are I wouldn't use it on a tank larger than a 20-29g regardless of whether the canister was taller or wider with same capacity. I like having lots of surface area and depend greatly on bacteria since I don't use carbon or chemical filtration that often. Where height vs width, a taller canister (filled with media) that uses the same internal volume as a wider/ shorter version would likely lose its flow rate faster over time since the water has further to travel in a more compressed area. On the up side, I believe you would get quicker results from the "tall canister" than the "same volume wide canister" in water clarity if you were starting out with fresh new media.
 
isn't it how much water per minute or hour. and then also the size of dirt it catches. or lets through? think they call it microns of particals. kinda like a water filter right?
 
there is no standard way of rating them though.

most manufacturers rate the rate of water flow without any media and under ideal conditions in terms of head loss.

almost everyone overrates their filters though.

for example, the Rena XP3 is a big and powerful filter, rated for up to 175 gallons.

However, I think it would be pushing it to put it by itself on anything over 120 gallons or so..

same with Aquaclear power filters. No one in their right mind is going to put a 'little' AC 70 on even a 65 gallon tank, at least I hope not.
 
Thanks for the comments so far.
My focus was more based on ME having empty canisters and an external pump and figuring out which would make the most sense. For example, A Rena XP3 and a Jebo 828 are both about the same overall dimensions. I know, I have both. They have different ratings and different size recommendations. The Jebo has a higher rating and recommendation, but has less pressure where the XP3 pushes water harder than I'd expect a filter to. So are we talking flow rate by the pump for better filtering, or capacity to filter what goes through? Granted, if I can pull water through 143 sq. inches, it will be better than 123 3/4 sq. inches, but the speed at which it moves through is a factor? or not?
 
I think it has a lot to do with the media supplied by the manufacturer as well. Their ratings I believe is not only on the gph, but with the media they supply with the filter. Now, if you change the media type, I do believe you will increase or decrease the filter effectiveness (rating) depending on the media you use. Other manufacturers don't supply media with their filters as well, and solely base their rating on the gph. Not all manufacturers base their ratings the same way. I base my filter needs on my own personal preference, as many others do.
 
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