Matching hose diameter to flow rate.

[Jared]

Hey gang,

I'm designing a med/large pond for the new property and have a few questions after reading through SO many "guides" which all say different stuff!

1.) My pond will be 9,000 gallons
2.) My skimmer will be about 32 hose feet from the waterfall filter
3.) The pump I think I should use is going to be pushing 7500 GpH at around 4' of head.
http://www.everything-ponds.com/sequence-4k-8200-energy-saving-pump.html

What's the most practical hose diameter? Some web "wizard" is suggesting 4" flexible PVC due to "higher than ideal" velocity at 2" or 3" hose. But, a contractor has told me 3" is fine. 4" PVC is really hard to find and it's expensive.
3" seems easier to find and is much cheaper.

Anyone have experience at these flow rates?

Thanks in advance!
~Jared

 

[sissy]

You are using an out of pond pump are you getting a leaf basket with and are you adding a UV .Not sure those will change everything on flow rate but you need to look into it

 

[Jared]

Yes, an external pump. There will be a Helix skimmer/filter at pond's edge. I'm considering a UV.

 

[sissy]

Reason I ask because some of your flow will have to go to that and it will have to go through it slower to be effective

 

[Meyer Jordan]

I would recommend installing a 'wye' at the pump outflow and plumbing dual 2" hose instead of a singular 3" hose. You will gain I.D. while using a hose size that is easier to handle.

 

[Jared]

Meyer you just blew my mind a little bit. Is this something you've done?

 

[morewater]

I would recommend installing a 'wye' at the pump outflow and plumbing dual 2" hose instead of a singular 3" hose. You will gain I.D. while using a hose size that is easier to handle.

I concur. The "splitting" of the outflow will allow for greater versatility. I don't recommend the "corrugated" line, but rather the smooth-bore line for better fluid dynamics. Longevity is an issue between the two. Use "quick couplers" rather than hard-install for ease of service and seasonal blow-out (shut down). This of course is wholly dependent on your location and freeze characteristics. They save a lot of time.

 

[Meyer Jordan]

I concur. The "splitting" of the outflow will allow for greater versatility. I don't recommend the "corrugated" line, but rather the smooth-bore line for better fluid dynamics. Longevity is an issue between the two. Use "quick couplers" rather than hard-install for ease of service and seasonal blow-out (shut down). This of course is wholly dependent on your location and freeze characteristics. They save a lot of time.

Yes, on my own pond. 7500 gph on 2 2" FlexPVC (smooth bore like Morewater suggested). Each line feeds a separate Biofalls filter.
You can use each independently or tie them back together at the terminal end with another 'Wye'.

 

[addy1]

I have a 3 inch feed into my pump (around 6800 gph) It Y's out to two different areas, each of those lines is two inches. I also use the quick couplers, on the draw side I use the rubber ones, on the pump out side I use the pvc screw on ones. Makes it real easy to remove the pump for the winter, around 10 minutes of work.

 

[MitchM]

Jared, below in my signature there is a head loss calculator that you may find useful.

 

[Jared]

Thanks Mitch,

I've used that calculator, which told me the 3" diameter wasn't correct.
The warning I get is "5.43 ft/sec - WARNING - this velocity is higher than ideal. Consider choosing a larger pipe size to reduce head!"

Should I run 3" pipe from the skimmer to the pump then 2x 32' 2" lines from the pump to my two bio-falls?

Would that be better/worse/same as running a single 32' 3" pipe to the falls then split that by "Y" to a pair of small 2" jumpers to each falls?
~Jared

Obviously, I'm only using the 7500 GPH pump to stay within the guidelines of turning over my pond's volume within two hours. If somebody tells me that I can get by with a smaller pump, I will. at 9,000 gallons, my pond will be a 32x15x3 kidney

 

[Meyer Jordan]

Should I run 3" pipe from the skimmer to the pump then 2x 32' 2" lines from the pump to my two bio-falls?

Yes. This would be the best configuration.