Benchmarking Filter GPH - The Planted Tank Forum
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post #1 of 7 (permalink) Old 12-20-2004, 04:15 AM Thread Starter
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Benchmarking Filter GPH

It's no secret that many filters advertised GPH could be inflated, so a few members have put their filters through the "bucket test". Had some extra time this weekend to do it myself, and thought it would be nice to have a dedicated thread.

Setting up the test: With a gallon jug, I found the exact mark of 5 gallons on a Home Depot bucket. The bucket was placed next to the tank and elevated with a stool and books, so the rim was equal to the height of the aquarium (~4'). Turned off the filter, placed the output line in the bucket, and grabbed a stop watch. I found the time taken to fill the bucket with 5 gallons.

A 2215 was tested in three ways: 1) With media set up the traditional Eheim way. 2) No media. 3) No media or spraybar. 2 and 3 obviously aren't applicable but was interested in it. The media was just replaced fully and less then a week old. The only build up was minor fluorite cloudiness.

1) 2:41/112 GPH
2) 2:30/120 GPH
3) 2:25/124 GPH

Eheim lists the pump output as 164 GPH and filter circulation as 135 GPH. That's a 32% or 17% drop depending on which stat is used. Anyhow, seems much less then the 50%-60% decrease I've seen on other filters.

Now, post your results!
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post #2 of 7 (permalink) Old 12-20-2004, 01:50 PM
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My ebay 2228 clone crossed the line @120 seconds. Last night, I did it with out the spray bar, and it was only a few seconds quicker. Both with no media. Now it's stuffed with walmart fluff, I may try again.

I have a life. Really.

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post #3 of 7 (permalink) Old 12-20-2004, 04:41 PM
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There's the pump GPH, and actual filter GPH. Many use the pump GPH to make it sound higher. Every application can also be different depending on how much tubing is used, and how much of that tubing is upwards (i.e., filter is under the tank) on the return line.
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post #4 of 7 (permalink) Old 12-20-2004, 05:01 PM
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I like controlled experiments like that. I'm also one of those people who just want to know ... like the fact that the spraybar reduces flow by 4 GPH, that's interesting to me.

I just want to be sure I understood correctly: You have the canister on the floor and the surface of the water is 4-feet from the floor level? It would seem to me that height (I believe they call it "head", right?) is a crucial parameter. I would think tubing diameter would be critical. I seem to remember from when I took fluid dynamics that fittings like elbows and tees reduce the flow.

All interesting stuff, nice work.
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post #5 of 7 (permalink) Old 12-20-2004, 05:33 PM
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re head etc

From what I have read every 90' elbow adds 1 foot of head height. However considering water will flow into a canister below which is a closed circuit head height should not make any difference since the mass of the water pushing down is the same as the water going up. All you should need is energy to keep it moving.
I've noticed a lot of canister using smaller output diameter hoses btw which I think would help in the output pressure as more water going down makes it easer to go up via mechanical advantage , upping the pressure while pump is running.
I think length of hose, cross section (ie is it slightly oval from coiling) and smoothness will make the biggest diffrence. I noticed after I cleaned my both my input and output lines(with flexi brush) that my flow dramatically increased.

Alll the eheims on thier website list both pump capacity and filtration capacity.
Depending on the model it varies from 15 to 50% .

15 tall
with pressurized c02 jebo 828 , 9w turbotwist uv. up-aqua co2 atomizer16/22
& small yoyo and striata loaches and praecox rainbows.
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post #6 of 7 (permalink) Old 12-20-2004, 05:42 PM
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This site wont be applicable for Eheims and Fluvals, but for those wanting a quick way to test the "true GPH" of regular powerheads, I use this site:

Takes into account the 90 degree Elbows, etc. Very helpful if you have a Sump.

110g - Vivarium (Dart Frogs)
180g - Reef
100g - Planted Tank (mainly Swords)
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post #7 of 7 (permalink) Old 12-20-2004, 06:53 PM
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Wow, thanks for posting this Chris. You may have seen my postings, but I'll copy them here anyway.
Jebo 828 160gph
Filstar XP-1 132 gph

Eheim ratings are much more real-world than the other companies I tested.

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