please help me understand intake bays

[combatwombat]

Ok i think i'm getting this. i don't know that i can work this out though so the pump pumps from the negative edge yet still
cycles through the full water column. my instinct tells me it would just circulate surface water.

That’s the trade off of a skimmer of any kind—skimmer box, intake bay, negative edge, etc. They are drawing surface water.

If you want to circulate the full water column, you will need to add another circulation feature like a bottom drain, jets, or a powerful waterfall falling into deep water.

 

[allif]

makes sense. we're planning to let the water re-enter the pond from the bog via a spillway. i'll try to get it as high above the pond water level as possible, and my son's been digging out in the fall zone so the ducks can splash and dive under the falls - it's pretty deep but we'll make it deeper still. whether that all creates a powerful enough circulation remains to be seen.
thanks!

 

[Rashad]

I think making it deeper there will make circulation harder right? if the flow from the bog waterfall hits the bottom of the pond it will spread out moving water from the bottom up to the surface. If it's deep, water from the waterfall won't flow all the way down and move around the water at the bottom. I could be wrong though!

 

[GBBUDD]

Negative edge 100 percent from the surface it draws what ever fell into the pond as fast as possible much like a skimmer .
An intake bay draws more from all of the heights of the column thus making it less effective in my eyes.

 

[allif]

I think making it deeper there will make circulation harder right? if the flow from the bog waterfall hits the bottom of the pond it will spread out moving water from the bottom up to the surface. If it's deep, water from the waterfall won't flow all the way down and move around the water at the bottom. I could be wrong though!

hoping someone else can confirm this? or refute? i'm digging down as we speak (just came in for a drink) but I can back fill.
it's a small pond, roughly 7x8 with a max depth of maybe 2.5 feet, including under the spillway. but the spillway will be raised maybe 1 foot about the pond surface. i can work it out but the ducks will certainly mix things up if nothing else.

 

[allif]

Negative edge 100 percent from the surface it draws what ever fell into the pond as fast as possible much like a skimmer .
An intake bay draws more from all of the heights of the column thus making it less effective in my eyes.

now that you say it, i can see that.
i still like the idea of a negative edge but think i'm going to keep things simple for now. we're going to build a screened frame
to protect the pond from leaves nuts acorns etc. i'll just use a net for feathers. i don't see how to work it otherwise, without an awful lot of re-engineering. and right now i kind of want to get this project back under way, those ducks are getting restless.

 

[combatwombat]

hoping someone else can confirm this? or refute? i'm digging down as we speak (just came in for a drink) but I can back fill.
it's a small pond, roughly 7x8 with a max depth of maybe 2.5 feet, including under the spillway. but the spillway will be raised maybe 1 foot about the pond surface. i can work it out but the ducks will certainly mix things up if nothing else.

@Rashad is correct. The idea is that you want the water from the falls mixing as deeply as possible with the water below it. So, the deeper you make it there, the more flow you will need over the falls to get it to mix down to the bottom. So, I wouldn't dig any deeper than you were already planning to go. Just make sure the falls isn't dropping on a shelf that's 6" deep or something.

 

[allif]

@Rashad is correct. The idea is that you want the water from the falls mixing as deeply as possible with the water below it. So, the deeper you make it there, the more flow you will need over the falls to get it to mix down to the bottom. So, I wouldn't dig any deeper than you were already planning to go. Just make sure the falls isn't dropping on a shelf that's 6" deep or something.

i get it. i had been thinking that a deeper section under the falls would promote upwelling and therefore circulation. but i see how you need the eater to reach the bottom to mix. thanks to both of you!

 

[GBBUDD]

It will also help keep o2 levels up for the high loads your going to be throwing at the pond

 

[allif]

It will also help keep o2 levels up for the high loads your going to be throwing at the pond

wont the falls add O2 whether the water reaches the bottom or not?

 

[combatwombat]

wont the falls add O2 whether the water reaches the bottom or not?

Yes, but the deeper you're able to inject oxygen, the healthier your pond will be.

 

[brokensword]

Yes, but the deeper you're able to inject oxygen, the healthier your pond will be.

CW, that's not true. Oxygenation occurs AT THE SURFACE, not in any bubbles/air dragged down below it. Meyer did some research/has a post about it where he states there is very little transfer from the bubble rising and the water surrounding. So, the idea here is to agitate the surface--that's where you get the oxygenation. And of course, since the falls is an agitation of the flowing water, there's a lot of surface oxygenated. So deeper isn't any better re oxygenation. Better to have a pond with a lot of surface area than one with a lot of vertical volume. Most ponds/lakes depend on the wind to agitate and mix air to water.

 

[brokensword]

wont the falls add O2 whether the water reaches the bottom or not?

yes, but even better if more of the pond surface is agitated on that last drop.

 

[brokensword]

i get it. i had been thinking that a deeper section under the falls would promote upwelling and therefore circulation. but i see how you need the eater to reach the bottom to mix. thanks to both of you!

you'll find that unless you have a lot of force (via pump, directly pointing at the surface) waterfalls don't 'go that deep' upon hitting the pond. I have my cam pointed such that I can see the effect of my waterfalls and the water column below. Observing the various floaters going by, there's not much movement downward.

 

[combatwombat]

CW, that's not true. Oxygenation occurs AT THE SURFACE, not in any bubbles/air dragged down below it. Meyer did some research/has a post about it where he states there is very little transfer from the bubble rising and the water surrounding. So, the idea here is to agitate the surface--that's where you get the oxygenation. And of course, since the falls is an agitation of the flowing water, there's a lot of surface oxygenated. So deeper isn't any better re oxygenation. Better to have a pond with a lot of surface area than one with a lot of vertical volume. Most ponds/lakes depend on the wind to agitate and mix air to water.

Ah. That makes sense. I think the deep mixing helps with circulation of deep water, bringing it to the surface to receive oxygen, right? Same idea as adding an aerator.