What does "Flow rate at 3' head 250GPH " mean

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Brian L

Aquarium Advice Apprentice
Joined
Jan 6, 2007
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What does "Flow rate at 3' head 250GPH " mean. I am trying to find a pump for my wet/dry filter. 90 Gallon tank. Predrilled for a wet/dry tank.
Brian
 
It means you can lift 3' high and flow 250 GPH. Head is the general term used for lift that a pump has to overcome. It basically takes back pressure into account. The same thing is used for commercial booster pumps, but all the numbers are much higher.
 
If the intake and the outflow nozzle are 3 feet above the pump, the flow will be 250 gallons per hour. If it is a canister filter, that figure is for the media baskets being empty. If it is a submersible pump, it should be somewhat accurate. Of course, length, diameter, and curvature of hoses will have an effect.

You need to find a sump guru who can tell you what kind of flow is good for your set up. I know HOB overflows have a maximum flow rating, so that you would not want to exceed that rating for your return pump. But built in overflows should be able to handle quite a bit, and 250 gph does not seem excessive for a 90 gal tank. In fact, you probably could run two of them?
 
Brian L - for a 90gal I would try to find a pump that will give you at least 500gph at the height your returns will be at. Or as TomK2 suggested run two 250 pumps if you set up allows this.
 
Idealconcepts said:
Brian L - for a 90gal I would try to find a pump that will give you at least 500gph at the height your returns will be at. Or as TomK2 suggested run two 250 pumps if you set up allows this.

Does an aquarium really need to be turned over that often in an hour? The more the better, but is it necessary? If you were to turn over a tank's volume twice in an hour let's say, would you be running into problems?
 
Brian L - It's not necessary to to turn over a tank that much but it reduces your changes of having problems.

If you kept say 10 neon tetras in the tank with 250gph you could get away with it. You might have fish poo in areas where there are dead spots and if you over feed the tank and left over food is left in the tank it would take longer to clear up the water. My guess with a good size tank your not going to just keep 10 neons and nothing else.

A benefit of a higher flow rate is you are able to run the tank water through the filter numerous times thus keeping your water looking cleaner sooner, as well as the pressure will move more of the waste eventually into the the filter intakes. When this happens your filter (actually the bacteria in your filter) can breakdown the waste (ammonia into nitrite, then from nitrite to nitrate) sooner thus reducing the changes of problems occuring with your tank.

For example on my my 300gal S/C American Cichlid and Aro tank I hve 2 pumps rated at about 1140gph at zero head, at about 6ft, this is the height my returns are at my estimate is each pump is producing about 600-700gph (I'm underestimating it) in addition I have a pump rated at 1017gph in the tank that is connected to a UGJ (Under gravel/sand jet) system that circulates the lower water column, my estimate is about 800gph.

A qoute that many aquariust use regarding turn over is you can never turn over your water too many times.

Does this help?
 
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