What is the appropriate pitch for a spillover ledge?

[CRUSH-IT!]

I have a spillover spa. It is about 2 ft wide at the spa and about 30" wide where it spills to the pool. It will sustain a nice looking spillover with about 55 gpm but requires in excess of 70 gpm to consistently initiate a nice laminar spill over. Below these flow thresholds the water just curls around the edge of the spill over and runs down the face of the tile. I will be having the pool resurfaced and would like to have adjustments to the spillover made at that time. I want to get a nice spillover with less flow to save money etc.

I am inclined to:
1) increase the pitch of the stone slab.
2) extend the slab 2 inches laterally beyond the aperture on each side to prevent water running laterally around the edges.
3) Alter the edge of the slab where it spills over to reduce the tendency of the water to adhere to the slab and just run down the face of the tile. (currently the face of the slab is pretty much square.

Any thoughts? How much of a pitch is reasonable? Is a half inch over a foot too much?

 

[ajw22]

The leading edge of the waterfall must have a straight or sharp edge to sheet or keep from hugging the wall. If you want a diffused or "rough" cascade, then you would make the leading edge rounded, and cut a groove on the underside to keep the water off the wall.

You can run a bead of silicone calk under the stone or a more permanent solution is use a diamond blade grinder to cut a slit under the lip of the stone 1/8 to 1/4 deep. It creates a drip edge to keep the water from wicking back on the wall.

I think the 24" wide opening at the spa widening to 30" at the spillover reduces the water velocity at the spillover and is the opposite of what you want.

@AQUA~HOLICS @mas985 may have ideas

 

[AQUA~HOLICS]

If the opening was switched 30” at the spa and 24” at the pool I don’t think this would be a problem.
I have spillways back cut towards the spa approximately 1/2“ to build up pressure to help with distance off the lip.

 

[Deleted member 312768]

I have a spillover spa. It is about 2 ft wide at the spa and about 30" wide where it spills to the pool. It will sustain a nice looking spillover with about 55 gpm but requires in excess of 70 gpm to consistently initiate a nice laminar spill over. Below these flow thresholds the water just curls around the edge of the spill over and runs down the face of the tile. I will be having the pool resurfaced and would like to have adjustments to the spillover made at that time. I want to get a nice spillover with less flow to save money etc.

I am inclined to:
1) increase the pitch of the stone slab.
2) extend the slab 2 inches laterally beyond the aperture on each side to prevent water running laterally around the edges.
3) Alter the edge of the slab where it spills over to reduce the tendency of the water to adhere to the slab and just run down the face of the tile. (currently the face of the slab is pretty much square.

Any thoughts? How much of a pitch is reasonable? Is a half inch over a foot too much?

I have those same dimensions I can send you a video of mine, it does not cascade- unless I crank up the spillway pump. I have stone extended and they slightly rounded the edge so no one would poke their eye out!

 

[CRUSH-IT!]

Im sorry Im late gettin back to all of you. I appreciate your insights. I think I will diamond cut the underside when the stone is pulled. I will do some experiments on the slope of the stone. I suspect a half inch or less would result in pretty fast flow. At my prior home the tile guy tilted it about 1/4".

Thank you again to all of you.