Calculating and measuring true gph

[Patrice]

I got 2 differents external pumps that are very close in gph. One is a fluval 204 and the other is a fluval 303.

So i tested the time it take to fill up a 4 gallon bucket.
No media, just the filters. I just need to know how to calculated the gph? I got 2.8 min on the fluval 303, and 5.3 min on the fluval 204. Now on they official manuel, the 303 is 177 gph and the 204 is 180 gph. And i am pretty sure that's not the true gph.

 

[Mebbid]

They don't factor in the head loss of the pump I would assume. The higher the filter has to pump the water then the slower it is going to pump it. Try raising the bucket up another foot and see what the flow difference is.

Also, most canister filters work by being gravity fed by the tank. Try raising the tank you are pumping the water from to an average aquarium height.

 

[Patrice]

You may be right, i wont do it because its hard work. Lol. I install the the stronger one. There a big difference between the 2 even if its not the right way

 

[aqua_chem]

1) Do you know how water one of those buckets holds? Some hold closer to 5 gallons, which will throw off your numbers.

2) Canister filters have no head height under normal circumstances. The pump only moves water; it doesn't push or pull it. As mebbid said, this is not the proper use of a canister filter, so the numbers would probably be quite a bit less.

 

[Patrice]

Thanks, now i know. And yes i have a line in the bucket.