New Pond Help (4000 gal. with Ultima II) - 1 Pump or 2?

[Akiko Creed]

Good day everyone,

First and foremost, if my below inquiry is already answered, please let me know by directing me to the link. I searched the forums, but cannot find exactly what I need; I may have overlooked something. The last thing I want to do is waste your time, especially since you all have been so kind. So, I will get to meat and potatoes...

Background (note: nothing has been dug out yet)

• Planned -
  • New build - 4,000 gallon pond (16 x 12 x 3)
  • Undergravel filter - 2" pipes, 1ft separation, with 1/2 inch holes; 3/4 inch gravel; 4 in. gravel on top of pipes
  • 2" flex sch 40 pvc piping for runs
  • "life support (LS)" area 25 ft from pond (25ft from waterfall (WF) to LS...PLUS 25ft from skimmer to LS)
  • WF is 4ft (approx) above pond water level
  • Small 10-15ft stream (bog stream)
• Purchased (for referenced question) -
  • Helix moving bed waterfall (24" weir) - plumed 2"
  • Ultima II pressurized filter (4,000 max GPH) - plumbed 2"
    • requires pump to push 10' head at 4,000 gph
  • Helix Skimmer - plumed 2"

Facts and Additional Information -

Based on waterfall calculations, I need to push 4,500-5,000 GPH over the WF, for the effect I want. however, the max volume, as stated above for the ultima, is 4,000 GPH. The max volume for 2" pipes is 5,400 gallons before friction loss and high energy costs becomes a huge problem for an external pump (based on my research).

I had one guy recommend a 6800 GPH pump... but, due to my setup, I am concerned that I may need to purchase a pump that is a higher GPH for the effects I want and need, which will place extra demand on piping and and the pump which will cause inefficiencies in my system and eventual breakdown of the pump.

Questions -

• Should I use a single pump or 2 pumps (one for waterfall, and another for skimmer and Ultima)?
• What pump(s) should I use?
• Could I use the 6800 GPH pump recommended and scale it back with little overall effect to the system.
• Should I use 3" or maybe 4" inch pipes instead? (is volume/pressure affected by a 3" to 4" pipe to a 2" inlet.
• If you were building this pond with the above information, what would you do?

I know this a lot, but any help on this is greatly appreciated. I thank yo in advance for ANY suggestions on any part of this.

-Akiko

 

[Meyer Jordan]

First of all, you will need a pump(s) that will give you a turnover rate of 1.5 to 2.0 times per hour. For your projected 4,000 gallons this means you will need a total flow rate of 6,000 - 8,000 gph. This can be accomplished with either one or multiple pumps.
What is the projected weir width on your waterfall?
What is a Life Support area? Are you referring to a separate structure for housing the pump and filters?
Piping can be 3" or it can be split into two 2" pipes.
We can discuss the under gravel filtration later.

 

[Akiko Creed]

First of all, you will need a pump(s) that will give you a turnover rate of 1.5 to 2.0 times per hour. For your projected 4,000 gallons this means you will need a total flow rate of 6,000 - 8,000 gph. This can be accomplished with either one or multiple pumps.
What is the projected weir width on your waterfall?
What is a Life Support area? Are you referring to a separate structure for housing the pump and filters?
Piping can be 3" or it can be split into two 2" pipes.
We can discuss the under gravel filtration later.

Hi Meyer J, thanks for responding!
The weir width is 24"

Sorry for that. Life support is what they refer to in marine aquariums. I picked the term up from an aquarium tour . Yes, the life support area is the place where the external pump, "bubbler" pump, and Ultima are stationed. I will build a small shed/hiding place for it.

OK dumb question,... when you say "split into two 2" pipes" Do you mean 2 separate "inlets", that join at a 3-way valve each side, and the 3rd side is connected directly to the external pump?

 

[Meyer Jordan]

when you say "split into two 2" pipes" Do you mean 2 separate "inlets", that join at a 3-way valve each side, and the 3rd side is connected directly to the external pump?

Yes. Pump outlet to 2" wye fitting. both 2" lines travel to destination connection where they are recombined with another 2" wye before connecting to destination.

Because you are effectively splitting the flow rate, only 50% will travel through each 2" line. The lower friction loss will actually reduce the Total Dynamic Head resulting in increased flow at the destination.

 

[Meyer Jordan]

The weir width is 24"

A flow rate of 3600gph at the waterfall weir would, I believe, give you all the 'Splash for Cash' that you really want. Anything more than this may be hard to control with that narrow a weir.