The box on my powerhead says it pumps 800 gph with no hose and at 5 feet, it pumps about 200. When purchasing this, I was unaware of the relation, but I have a question. Is the feet the vertical distance I am pumping upward or the actual hose length? I don't know the physics they were referring to. Anybody know anything about this topic? I can get 100 gph if I lessen "the distance" 1 foot.

Thanks!

ed,

this is a very good question in that most cannister filters are designed to be stored under the tank. thats anywhere from 2 1/2 feet to 4 feet. i wonder if those companies are taking that into consideration? im sure that they do.

anyway, it means vertical distance that the water is flowing. although, if youve got a ridiculously long hose traveling horizontally, im sure that you lose a few gph's. not much though.

hope this helps

oh yeah! and yes, if you lessen the vertical distance by one foot, youll gain back 100 gph.

Excellent. That means I'm actually at 3.5 feet rather then 5 feet (the length of the hose). That makes around 200 gph difference or about 3x.

Thanks.

The head height is the working lift distance, but the length of the tube adds resistance, thus increasing the work load. In a perfect world there would be no resistance and you would simply be dealing with lift. But you need to figure the length also.

Is there a formula for this? The box does not specify whether the distance is hose or heigth. This is extremely helpful.

I certainly know that hose length affects water pressure. Why don't one of you guys ask a local plumber? He might know something about it. I'll be taking up this topic in college sometime soon. I might answer some of your questions in a month or so. If you know an engineer, you could ask him.

Interesting. It may depend on the type of hose too. My hose is slightly elastic. A PVC pipe may subtract less pressure but I don't know how much.

Actually, bends in a hose will lower the pressure because it's hard for water to pass through it. So a 90deg turn in your hose will lower pressure.

ed,

ive got a uv filter coming and ive been doing some research on this stuff. heres a good page to read (about 4 or 5 times in a row, that is! ) youll see what i mean: http://www.reefkeeping.com/issues/2002-05/rn/feature/

do some googling around using some key words/phrases from the page, im sure youll be able to find some exact numbers for your application.

paul

So true guys, I have always had this thought in my mind but just didnt thinking it all the way threw. Most of my canisters dont have that much relax in the hose lines and the only one that has a turn in it is the intake hose........Good topic guys :thumb