help with water pumps

[JOSH]

ive been looking at getting a water pump but i want to know what they mean by this on JL aquatics

Flow Rate at 0' Head: 200GPH
Flow Rate at 4' Head: 125GPH
Flow Rate at 6' Head: 15GPH

[mr_alberta]

That's the flow from the pump at the given head pressure. So, using your example below, the pump pumps out 200gph normally. Now if you had to pump water 4' straight up, the output drops to 125gph due to pressure and friction within the pipe.

[kwirky]

can you post a link to the pump you're looking at, and explain how you're going to be using it?

[mark]

Below is a great summary of lots of pumps all on one page, the more info is flow/head plots.
http://www.reefs.org/library/pumps/

[JOSH]

dont really have a pump in mind yet, but its just gong to be a return pump from my sump

[kwirky]

what size is your tank? what size is the overflow (the drain) drilled for in your tank? what size is the return drilled for (for the pump)?

[JOSH]

okay heres the info on my pump

EcoPlus-396 pumps 396 gallons per hour (GPH) / 1500 liters per hour (LPH) at an even head with a maximum pumping height of 6.39 feet or 1.95 meters. Includes 1/2 inch and 3/4 inch hose connections. 110V, 25 watts, measures 6.4 inches long by 3.1 inches wide by 4.5 inches tall.

so are they saying at 6.39 feet im still getting 396gph?

i have 3/4 bulkheads and i think 1/2 hose with a travel distance of about 34 inches

[kwirky]

how large is your tank? that'll contribute to the head pressure. 50 gallons of water trying to force it's way against your pump can be almost 3' of head alone.

if you already bought it, do an experiment. go to the bathroom, hook a hose to the pump, and raise a 5 gallon bucket up the same height as your tank. then time how long it takes to fill the bucket. that's your water flow at the head pressure WITHOUT your tank's water forcing down on the pump. it'll give you a rough estimate if your pump's strong enough to at least get the water to the bottom of the tank at the flow you want.

oh, and if you have a gravity fed overflow at 3/4", then reduced to 1/2", i'd be careful. that can only handle a flow of about 90 gph, since it's gravity fed. and each 90 degree elbow will reduce that flow by 25%

how big IS your tank? is it a nano?

[mark]

Max head is where the pumps rolls off to zero output.

Depends on pump curve, how return is routed but guessing your bulkhead/hose could handle your pump volume from that head. Seems common advice to restrict pump output with a value, to prevent overflows maxing out and tank overflowing.

Often numbers like 3/4" bulkheads rated 300gpm, 1" - 600gph. Could check those numbers against how overflow or tanks manufacturers rate volume.

[JOSH]

its a for a ten gallon nano, im expecting to lose some of the GPH rating but i should see a fair increase in flow compared to the 250gph canister im using right now i would imagine