Canister Rate of Flow

**saki** · 05-22-2009, 04:15 AM

How important is canister rate of flow? I've been looking at the Eheim 2215 and the Rena Filstar XP2. The flow from the 2215 is 163GPH while the XP2 is 300GPH. What is the benefit of having a higher rate of flow? Are there certain types of tanks that need more than others? It is my understanding that because the 2215 has a lower rate of flow it actually does a better job filtering... so why does the XP2 have nearly 2X the flow?

**OscarFan** · 05-22-2009, 04:26 AM

More flow is for bigger tanks. You should have6-12 gph for every gallon of tank.

**saki** · 05-22-2009, 04:33 AM

I'm still very confused about it... the 2215 is rated for up to a 93 gallon tank and the xp2 is rated up to a 75 gallon tank. Wouldn't it stand to reason that the 2215 should have a much higher rate of flow?

**Dave66** · 05-22-2009, 04:45 AM

saki,
Published gallon per hour rates should be taken with a healthy grain of salt. The GPH ratings are set by the manufacturers in laboratory conditions with no media at all in the filter. So take the published rating, divide it by half, and that'd be about your real GPH in your tank.

Dave

**Flowcus** · 05-22-2009, 06:23 AM

Also take into effect the fact that you must pump water up to your tank. So for every 1ft of elevation you generally lose a decent chunk of the rated GPH.

Also the general rule of thumb for most aquarium keepers is turn the tank 10+ times an hour... Your basis for what filter you purchase, or how much you filter is all dependant on what fish are kept, and how the tank is stocked. If you're keeping messy fish like Plecos, Oscars, or Puffers to name a few... you're going to want to over filter and turn the tank 10+ times an hour. But if all you're keeping is a Betta and a few tetras or a small school of fish then thats a bit of overkill unless you can afford the better filtration with no issues.

There is no such thing as over-filtration of a tank! And you're always better off going with a much larger filter then what is rated for your tank. Never NEVER go based off a manufacturers suggested print on the box. This is seemingly just a ploy to convince people to buy their product. Most HoB's that are rated for 50gallon tanks are actually only sufficient in filtering a 20 or 30gallon tank.

**Fishguy2727** · 05-22-2009, 01:20 PM

Keep in mind that the flow through the canister itself doesn't need to be that high. If the flow is too fast the media can't do its job as well. Flow in the tank itself should be a little higher and enough to keep debris moving until the canister can do its job.