DIY Vanishing 59ft Edge - Sanity Check

[Bluejean]

Building a DIY spillover pool in haste and hoping to minimize errors...

Starting new tread with overview and request for general guidance.

Project:
Cast Concrete spillover pool on cliff edge. (not gunite/shotcrete)
Offgrid solar electricity, no permitting, no one to save me from myself, etc (Ranch Property)
~900sqft, ~29,000g
~59ft spillover weir
~51" pool depth
Pump/Basin room 4ft from Pool wall - Very short plumbing runs
Basin Floor is 12ft below top of pool water (6ft difference in typical basin to pool water level)
Perimeter trough collection gravity flows into adjoining basin (no drains in trough)
No skimmers (intend to push water over weir)
Not looking for robust waterfall over weir, but cleaning benefit

- Pump 1 Suction: direct from Basin (returns to pool via 4" manifold for pushing spillover - Wall Jet count TBD - perhaps 8-10?)
- Pump 2 Suction: wall suction ports (returns to pool via 4" manifold for filtration, heat pump in line)
- Plumbing manifolds: 4" primary trunk lines to/from pump room feeding 2" stub outs though pool wall (1.5" jets)

Concerns:

- Weir elevation compared to pool deck elevation. Is <1" below coping viable? Looking for zero-edge style, but not installing gutters on all 4 sides.
- Is one powerful pump sufficient for spillover of this size (4" trunk line, very short runs from pump).
- Is one 2nd pump for conventional recirculation and Heat Pump sufficient?
- Connect each pump to their own filter?

thank you for any guidance! This is certainly a ready, fire, aim DIY project....

 

[JamesW]

The water velocity in a pipe is determined by its size and the flow rate through it. Below is a table of standard pipe sizes and the recommended flow rates for two different velocity specifications.

Pipe Size	6 ft/sec	8 ft/sec
1.5"	38 GPM	51 GPM
2"	63 GPM	84 GPM
2.5	90 GPM	119 GPM
3.0"	138 GPM	184 GPM
4.0"	235 GPM	312 GPM

Equipment Pad Best Practices - Further Reading

www.troublefreepool.com

Here is a Weir Flow Calculator allowing the input of Total Flow, Lift and Weir Wall Length.

https://claude.site/artifacts/61b34781-8e73-4bb6-bcdf-cdfdff5437d0

 

[JamesW]

To get a 1/4" lift, you will need about 265 GPM, which will require 5" PVC to stay below 6 ft/sec.

With a short run and a pump at a lower elevation, 4" will probably work.

Maybe do (2) 3" pipes.

 

[JamesW]

WhisperFloXF® VS 5HP Variable Speed Pump

The WhisperFloXF VS 5HP Commercial Pump is the first five-horsepower variable-speed pool pump that runs on single-phase or three-phase power.

www.pentair.com

 

[Bluejean]

The water velocity in a pipe is determined by its size and the flow rate through it. Below is a table of standard pipe sizes and the recommended flow rates for two different velocity specifications.

Pipe Size	6 ft/sec	8 ft/sec
1.5"	38 GPM	51 GPM
2"	63 GPM	84 GPM
2.5	90 GPM	119 GPM
3.0"	138 GPM	184 GPM
4.0"	235 GPM	312 GPM

Equipment Pad Best Practices - Further Reading

www.troublefreepool.com

Here is a Weir Flow Calculator allowing the input of Total Flow, Lift and Weir Wall Length.

https://claude.site/artifacts/61b34781-8e73-4bb6-bcdf-cdfdff5437d0

View attachment 626826

Thank you!

I previously reviewed your posts with these tables to come up with my default design. I am assuming 1/4" of head is more than acceptable if I am not concerned with the weir as a water feature (instead as a cleaning mechanism and steady-state aesthetic feature from patio above)? The outside view of the weir & spillover is only for the deer and raccoons below...

I could easily plumb the return manifold, split in half (a 4" main trunk feeding each half from the pump room. They could be connected to separate pumps or combined for single pump (both with suction directly from basin/tank)?

 

[JamesW]

Here is a calculator that allows you to input Speed, Head Loss and Flow.

Claude Artifact

Try out Artifacts created by Claude users

claude.site

 

[JamesW]

plot y = -0.0007x² + -0.0203x + 84.5, x from 0 to 300 - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.

www.wolframalpha.com

 

[Bluejean]

Here is a calculator that allows you to input Speed, Head Loss and Flow.

Claude Artifact

Try out Artifacts created by Claude users

claude.site

View attachment 626845
View attachment 626844

thank you!


Here is my CAD file for the elevations involved...

I plan to install pumps and valves directly above the basin tank (as insurance). The suction line can be measured in inches vs feet.

Distributing return jets from a 4" return manifold/trunk is easy to do. How many wall jets seems sensible? (Divide flow rate of 4" by flow rates for 2"/1.5" ?)

 

[Bluejean]

To get a 1/4" lift, you will need about 265 GPM, which will require 5" PVC to stay below 6 ft/sec.

With a short run and a pump at a lower elevation, 4" will probably work.

Maybe do (2) 3" pipes.

Thank you for the guidance!

I realized I might be misunderstanding the (2) x 3" pipe suggestion.

My basic configuration would be a 4" line extending about 4-5ft from the pump (to outside of pool wall) and then splitting with a T. Each 2" inlet would branch off this 4" trunk.

Do you suggest breaking up the main trunk, with one serving nearby inlets, and the other serving those a bit further away? The total relevant pool perimeter pipe length is about 65 linear feet (between inlet jets on either end of trunk line)

Would I bifurcate into two trunks immediately after the pump? (or am I misunderstanding?)

thank you!