CW's Back Yard Water Garden Begins!

[combatwombat]

Toddler is officially potty trained. She picked it up in 1 day. Awesome. Now back to work on the pond. Fixed the low edge on the negative edge using sand bags filled w/ dirt. Have changed the plan enough times that I don't remember why I cut it down anymore, but at least that's done.

Next, I need to figure out the construction detail on the weir. That is a critical point because I want the water to be pretty "thin" as it goes over the weir so if the pumps shut off, the amount of water in motion can be captured with plenty of room to spare. This will ensure that rain water that collects in the cistern over the winter isn't wasted if there's a power failure.

To do this, I think I'll do something like this:

A piece of flagstone is used to set the height of the weir inside the pond. The pond liner is then folded into a loop in front of the flagstone with the top of the loop 1/2" below the top of the flagstone. The depth of the weir is then extended out over the cistern, built up with boulders, then a bib liner + bead of foam to keep water flowing over the flagstone on the top.

All of this gap area and liner loop will be filled with foam and small gravel to protect it from UV rays or abrasion from above.

Here's the liner detail close up:

The key detail in keeping water in motion very low is the liner loop. Should the pumps ever go off, water level in the pond will settle just 1/2" below the level of the flagstone/waterfall weir. With a wide weir, water in motion should stay very thin, allowing me to save maximum space in the cistern for winter rain water—hopefully never having to top up from the hose.

The reason the weir is extended out over the cistern is to allow me to hide the liner loop and protect it. Without that, it would be exposed to the sun and susceptible to damage. And it would just be ugly.

 

[GBBUDD]

1. HOW MANY GPH IS YOUR PUMP
2. FABRIC............... COVER THE LINER IN FABRIC EVERYWHERE BUT WHERE U WANT TO SEAL IT TO THE FLAG STONE THEN PLACE FABRIC over that

 

[combatwombat]

1. HOW MANY GPH IS YOUR PUMP

Don't know yet. Likely in the 10-15k range.

2. FABRIC............... COVER THE LINER IN FABRIC EVERYWHERE BUT WHERE U WANT TO SEAL IT TO THE FLAG STONE THEN PLACE FABRIC over that

Yes. This pond will have liner covered in fabric everywhere.

 

[GBBUDD]

Don't know yet. Likely in the 10-15k range.

i run 12k NEGATIVE EDGE IS LESS THEN 24" wide and my pond drops about 3 inches just from the power going out now my edge is not a flat edge either its close but i went for natural looking semi flat rock over flag stone

 

[combatwombat]

i run 12k NEGATIVE EDGE IS LESS THEN 24" wide and my pond drops about 3 inches just from the power going out now my edge is not a flat edge either its close but i went for natural looking semi flat rock over flag stone

I have 8’ of weir to play with. Could choke it way down to get fat waterfalls or leave out wide open to do more of a weeping wall.

I also don’t love the idea of flagstone, so still exploring other options that will achieve the same goal. Big rocks over the flagstone to choke down the weir could be a middle ground.

 

[GBBUDD]

Id keep it as wide as possible less likely to have fish swim over the edge and less water drop in power loss

 

[combatwombat]

103º today. 114º tomorrow. 113º on Monday. I LIVE IN PORTLAND!

Wish I'd finished the pond this Spring.

 

[GBBUDD]

Finish shminish fill that puppy up and live there for the next week

 

[Lisak1]

Id keep it as wide as possible less likely to have fish swim over the edge and less water drop in power loss

100% agree. Fish will be less likely to swim over if it's a shallow band of water passing over the rock. A nice thick stream will seem like a destination vacation.

We lose about 3 inches also when the pump is shut down - we knew our outlet rock wasn't fully foamed, but whatever... it all runs into the rain exchange, so we focused on getting the negative edge rock set at the right height and level.

 

[GBBUDD]

I purposely did not make my negative edge rock perfectly level as i got a piece i loved as one side is longer hanging out over the falls this way i got a trickle all across the longer section and a harder stream to the side looks very natural

 

[Lisak1]

i got a piece i loved

We did the same - chose the outlet rock right from the start and set it aside. Worked the whole pond around that final rock. Took us about a day and a half to argue through the final placement - I think there were a lot of nerves involving that final water level! Seems silly now, but at the time every rock felt like a decision.

 

[MTguy]

I recently "completed" my negative edge from pond to cistern. I'm running about 10000 gph over approximately 16" of weir and I get about a 1.5" rise from that. I have had fish swimming over it, but I also wanted to keep the area more narrow to ensure I'm drawing enough current to bring debris to the cistern area. I'm still tweaking everything, but that darn negative edge was the part that gave me the most stress.

 

[combatwombat]

I recently "completed" my negative edge from pond to cistern. I'm running about 10000 gph over approximately 16" of weir and I get about a 1.5" rise from that. I have had fish swimming over it, but I also wanted to keep the area more narrow to ensure I'm drawing enough current to bring debris to the cistern area. I'm still tweaking everything, but that darn negative edge was the part that gave me the most stress.

10,000 gph through 16" is pretty massive flow! Glad it's working well for you. Did you start wider and choke it down based on performance?

 

[GBBUDD]

Trust me if you want surface draw /pull make it wider and shallower.
Wheres the pics geeez you guys know the rules

 

[MTguy]

10,000 gph through 16" is pretty massive flow! Glad it's working well for you. Did you start wider and choke it down based on performance?

I did. I actually had it about 12" in the design phase, redid some numbers and realized I was going to have way too much height in my water flow so I opened it up to about 24". Then, when I got it up and running I saved the neg edge for last to finish. That's when I choked it down a bit. One point of clarification, I'm probably only getting a little over 7000 gph actual flow rate after accounting for head loss. Originally I had the post written that way, but must have gotten rid of the verbiage while correcting my english.

I went with the narrower opening in general based on one of the aquascape videos (or one of their certified contractor's videos. I don't remember which). So far so good, but the fish do like to get up in that area. It doesn't help that I have a big log there that they can probably see as a perfect shelter.