Pump Flow Rate VS ID Tubing?

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Ok, So I have my new Pondmaster 950 and my new Pressurized Bio/Mechanical UV Filter. My question is: On the Pump Box it says "Minimum Outlet Inside Diameter of 1-1/2'' is required for maximum Flow" Now, The threaded end is only 3/4'' OD and the Filter Has 3 - 1 inlet and 2 Outlet step down slip on attachments (1'', 3/4'', 1/2''), Would my flow rate be minimized using 1/2'' ID tubing since the Pump ID outlet is only 1/2'' and the Filter inlet Starts at 1/2'' or would it flow faster (Higher Head Height) with same or little less outflow? Thanks! Sorry if confusing lol :goldfish:
 

koiguy1969

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the 1&1/2" ID tubing is for the upper end of the filters flow rating. but at only 950 gph on a pressurized filter its likely that size tubing isnt neccessarily "required". 1" on the input is probably fine, 1&1/4" will probably fit on the outlet, without the stepped hose adapter installed.that said.. the larger the tubing used both on the 'input' and 'output' of the filter means less flow resistance. and a pressure filter adds enough resistance on its own. it almost immediately starts building resistance in flow as its mechanical foam(s) start collecting, and holding debris and "clogging up". one of the outlets is usually for backwashing and doesnt need a hose on it. except while backwashing (cleaning the filter). the rest of the time its idle. usually even capped off. ( if ones supplied.)
 
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Thanks for the fast response Koiguy, So I can't get away with 1/2'' tubing? I just have a 20' roll of it and wanted to use it somehow if i could since by the time the flow gets to the Filter it would be around 750-800GPH? Would it hurt the Pump for me to use 1/2'' when it's rated at 3/4''? Thanks for all the help!
 

koiguy1969

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well.. 1/2" hose will restrict flow more than 3/4", and likely reduce the maximum flow of the pump. you might get the full 950gph at 3/4" but with 1/2" you may only get 900 or even less (just a random guess). restrictions in flow are more wear and tear on a pump as well.
what are the flow ratings on the filter? if you use a pressure filter, its a good idea to go with a pump rated at the higher side of the pumps ratings. this isnt as important for the filtering as it is the backwashing, a stronger pump will flush the filter more effectively.
 

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You can experiment with the 1/2" hose hook it to the pump in your pond or bath tub and measures the flow for a minute
It will be a lot more with with the larger hose , more flow for the same buck, more enjoyment
 
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Ok, So i should go with 3/4'' then, They only sell 3/4'' Corrugated at Lowes and HD here, would that restrict flow with it being Corrugated? And if not, then since the Filter starts at 1/2'' where the water goes in and out then should I change the stock fitting on the filter? The Filter recomends a pump with a flowrate of at least 400GPH but not more than 1,500GPH.
 

koiguy1969

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those step up hose adapters are made to be cut at the part that fits the size hose your using. they start off at 1/2" then step up to 3/4" then to 1"... usually 1&1/4" hose fits on the port without an adapter on.... i would have went with 1200gph or up. but thats just me.
 
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Jason,

It is recommended to use at least the next size tubing up from the pump outlet diameter to maximize flow. If your pump outlet is 1/2" diameter, then you should be using 3/4" tubing if not larger.
Since fittings like couplings or elbows and valves and even the filter itself restricts flow, the larger you go with the tubing the better as you can make up some of the losses created from the fittings
and filter by reducing the losses created by the tubing.

The coefficient of drag (or friction of the walls of the tubing) is of importance as this can reduce the flow rate. You want LAMINAR flow restrictions only - which is just the restrictions based on the confines of the cross sectional area of the tubing and not turbulence or friction from the side walls. A smooth walled tube is best. Corrugated tubing, if it is corrugated internally, will create eddy currents and turbulence which will restrict the water flow.


Here is a helpful statement from the Pondmaster pump website explaining a bit of this and some other highly informative details. I obtained some of the information for my figures from here:

What Does Head Height (shutoff) Mean
cleardot.gif
All pumps produce water flow and pressure. The water flow is easy to see when you plug in your pump especially as it flows over your waterfall. On the other hand, pressure cannot be seen and is sometimes difficult to visualize. Pumps are rated in Head Height which is an easy way to visualize the pressure a pump produces. One pound per square inch of pressure will lift a column of water 2.3 feet in the air so that a pump that has a shutoff height of 34.5 feet produces 10 psi of pressure. This is important to understand because the higher a pump has to lift water, the less water it can deliver. Naturally, a pump will deliver more water to a lower waterfall than a higher one. Head Height charts or graphs tell you exactly how much volume a pump will deliver at any given Head height. You may see 2000 gph @ 5' of Head.

In designing your pond you will need to know the head height of your own system. It is not enough to know just the highest point above the pond as there are other variables to consider. The water from the pump is carried to the waterfall via tubing, and the size of the tubing and the number of fittings will come into play in determinging what pump you will need. Both tubing and fittings cause friction resulting in a reduction of water flow which in turn can cause the pump to work much harder producing less flow. In order to keep this friction loss to a minimum, always increase the tubing at least one size larger(if possible)than the outlet of the pump. If the outlet is 3/4", use 1" or larger plumbing. If it's 1-1/2", go up to 2" tubing. There are several shortcuts in computing the total head required.

For every 10' of Tubing, add 1 foot of Head
For every Check Valve, add 1' of Head
For every fitting, add ½ foot of Head

So, if your waterfall is 5 feet tall, with 20 feet of tubing and two elbows and a check valve, your system would have a total head of 5 + 2 + 1 + 1 = 9'. with this information you can check the manufacturers charts to see which pump gives the flow you need at 9' Head. Keep in mind that in this example we did not calculate the addition of a pond filter which in itself can reduce the flow as much as 20%. In most cases it is better to opt for a larger pump as you can generally reduce the flow but if your pump is not large enough there is nothing you can do to increase the flow.


Hope this helps you and others.

Catfishnut
 
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Well that explained a lot! Thanks Catfishnut, I did end up buying 3/4'' Water heater hose since it fits the same adapters as pond fittings!
 

koiguy1969

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vertical tubing is 1 foot of head per foot .. 10 feet of horizontal running tubing equals 1 foot of head. but head does neccessarily start at the pump. on a submersable pump the head starts at the waters surface, not the pump... and fittings dont neccessarily add a foot of head. elbows will add much more head than staight thru couplers. 90*s will be much more than a 45*, and the 45 will add more than say a 22.5* or a 15*.
 
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Jason,

I believe you will be in an acceptable range with the 3/4" hose. You can double check this after the entire setup is complete by measuring the water at the exit point of your filter unit using a stop watch and a 55 gallon barrel. I know that you won't get 950 GPH simply because your fittings and filter will restrict the flow as in any system, but you should get 65-(75)-85% of that and that would be fine.

catfishnut
 

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the sight i was on koifishponds.com has lots of info on pump rates wattage and amp rates and hose flow rates under there pump area .
 
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Well I should Have the Pond Built and done after the weekend if the Rain Water ever settles in the hole, was 6'' high yesterday, today only 2'', HURRY UP :grumble: lol, So I guess I will find out then, I also got enough 3/4'' Hose (100ft) to use for my Two 520GPH pumps that i was going to use 1/2'' on as well. Thanks again :razz:
 

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