Intake Bay Design Equations and Numbers Needs


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I'm investigating the feasibility of using an intake bay instead of a skimmer on my pond design. I have watched some videos and I like they way the look and function but I haven't been about to find the info needed to design one to my needs. Can anyone help me find the following information?
1. What is the ideal ratio of pond surface area to flow rate into the bay?
2. Once flow rate is determined how is inlet channel width and depth determined?
3. What is the ideal ratio of bay surface to flow rate?
4. If I'm using gravel over aquablocks in the bay, what depth of gravel and what size gravel? I'm assuming this would be much shallower than a bog filter and only larger gravel would be used.

Thanks
 
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brokensword

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HEY!!!! @GBBUDD and @combatwombat : Be ye deaf? This is a job for either of you skimmer engineers! Sheesh; the poor guy/gal's been waitin'!!!

Hopefully, @jgell , someone rousts our two pond derelicts out of their slumber and they wander in to give you a bit o' advice, and soon!

;)
 
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someone rousts our two pond derelicts out of their slumber and they wander in to give you a bit o' advice, and soon!
I'm in no hurry. I have redesigned this pond many times and each time my wife has had issues with it. Originally it was about 2250 gallons and near patio. She was concerned it would not leave enough room for her future pool and pool house so she told me if I build it farther away I can make it as big as I want. The current design is 12000 gallons with a 300sqft bog filter. We will see what happens when she sees how much it will cost. I think it is a pretty good deal, the pond got 6x bigger but the cost has only gone up 3x.
 
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Real quick while I have a moment: The most important part of intake bay design is sizing it and that is based entirely on flow rate. Rule of thumb is 1 gal of storage for each GPM of flow rate. So if you are pumping 5000 GPH, that is 83 GPM and you will want to size your bay to hold 83 gal, or 5 small aquablox. Even numbers are easier, so round up to 6 blocks for ease of design and extra margin.

Can also use milk crates or similar placed upside down. They can be reinforced w/ 1” PVC spanning the center. Plenty strong to walk and to stack medium sized boulders on.

Gonna have to consult my notes later re: width of weir. Wider= thinner water = better skimming, but you can run issues if you get too thin and have much water level fluctuation. Believe Aquascapes specs their designs at around 12” of weir per 5000 GPH. Need to double check that, though.
 
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I understand the lure of intake bays as theres little issue with fish or wildlife. But in the same regard once debris falls onto the pond theres realy little to no pull on the surface to draw the leaves in. It realy does next to nothing as far as skimming is concerned. So if you have lots of trees it could be an issue. If you plan on being home all the time and you can use a net to remove whats pulled into the bay then yes its a good match. But if not i prefer a negative edge. That drops into a small catch pool. Yes same idea as debris sitting in the water butttttt your water level in the pond stays a constant and that is huge in my book. The water only fluctuates in the catch pool. And for me that is supplied by my cistern so only it has water fluctuation.
 
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A negative edge would be great but the reservoir it would require makes it less appealing. Would an intake bay at least be better than a skimmer? Is there flow rate cuts on these options? Somewhere in a comments sections on one of the videos I think I remember someone saying that less than 8000gph a skimmer is good enough.
 
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Skimmers can work great even on mid to larger ponds mine was around 12000 and my skimmer system worked great i have a video in my blog that shows a gopro on a float that gets in the current of the pond and within two revolutions around pond it gets sucked into the skimmer i have the HElIX skimmer it worked very well and always pulls from the surface. I am a big fan of surface skimming removing anything that falls in the pond that floats that it gets sucked to a collection screen for easy maintenance. The standard setup has a matala pad in the simmer below the basket strainer . In the fall you can remove the basket strainer and matala and install a triple basket so hold a slew of leaves that drop in the fall
 

Jhn

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I understand the lure of intake bays as theres little issue with fish or wildlife. But in the same regard once debris falls onto the pond theres realy little to no pull on the surface to draw the leaves in. It realy does next to nothing as far as skimming is concerned. So if you have lots of trees it could be an issue. If you plan on being home all the time and you can use a net to remove whats pulled into the bay then yes its a good match. But if not i prefer a negative edge. That drops into a small catch pool. Yes same idea as debris sitting in the water butttttt your water level in the pond stays a constant and that is huge in my book. The water only fluctuates in the catch pool. And for me that is supplied by my cistern so only it has water fluctuation.
Idk my intake bay pulls all the floating crap into it, which is mostly plants that are getting ripped up by koi and those annoying helicopters seeds off maple trees this past spring. I do have those Aquascape power heads in the pond creating a circular flow near the surface, so surface debris gets pushed in the direction of the intake bay. Will say leaves aren’t an issue with my pond, as none really fall into it. Mostly went with intake bay over negative edge due to the turtles in my pond.

Agree that you can size a skimmer for a large pond, still use a skimmer at the far end of my pond by the bridge to feed one of the bogs. The other skimmer is abandoned at the moment, in favor of the intake bay, but May end up putting a pump of some sort in there if I add another water feature like one of the 4-5’ tall urns…..

With the intake bay as well, you can always add or remove rocks at the weir/entrance to the intake bay to create the desired effect. Ie widening/narrowing the weir, lowering/raising the depth at weir entrance even after the pond is done, if it doesn’t come out how you imagined.
 
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but the reservoir it would require makes it less appealing.

That's the MOST appealing part about a negative edge... other than no skimmer to babysit that is. You don't need a massive reservoir - although the bigger you can make it the better, in my opinion. It can add significantly to the cost of a build as Aquablox are pricey, but the ability to store rainwater is priceless - if you're in an area where it rains, that is. And as @GBBUDD the level of your pond never fluctuates.

If not, you can still build a negative edge and use no more blocks than you would for an intake bay. It's really just a matter of how deep the water is in the "skimmer" area.

But again - matter of preference. A few times a year we have a crabapple that drops all it's blossoms (or leaves in the fall) in one week's time. It's a lot of debris, but our negative edge handles it without a blip because once it's over the edge, it's out of the pond. An intake bay - unless it were large - might struggle to keep up with a big debris dump. And a standard skimmer would require cleaning out several times a day for those few weeks every year.
 
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That's the MOST appealing part about a negative edge... other than no skimmer to babysit that is. You don't need a massive reservoir - although the bigger you can make it the better, in my opinion. It can add significantly to the cost of a build as Aquablox are pricey, but the ability to store rainwater is priceless - if you're in an area where it rains, that is. And as @GBBUDD the level of your pond never fluctuates.

If not, you can still build a negative edge and use no more blocks than you would for an intake bay. It's really just a matter of how deep the water is in the "skimmer" area.

But again - matter of preference. A few times a year we have a crabapple that drops all it's blossoms (or leaves in the fall) in one week's time. It's a lot of debris, but our negative edge handles it without a blip because once it's over the edge, it's out of the pond. An intake bay - unless it were large - might struggle to keep up with a big debris dump. And a standard skimmer would require cleaning out several times a day for those few weeks every year.
Question for you - Is there a problem with the gravel in your negative edge area getting clogged up by small debris, necessitating regular cleaning? I really like the idea of a negative edge, but... I know how much little crap I have to regularly clean out of the skimmer baskets/mats & can't imagine what that would do to gravel. Being in the middle of the woods, I have a TON of debris that falls into the pond.
 
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you can still build a negative edge and use no more blocks than you would for an intake bay
In the Modern Design Aquascaping Inc. video he said a negative edge requires a reservoir twice the volume of the water in motion. Can you get away with a much smaller reservoir?
 
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In the Modern Design Aquascaping Inc. video he said a negative edge requires a reservoir twice the volume of the water in motion. Can you get away with a much smaller reservoir?
Yes ... but the problem with a negative edge is the size of the pond the size of the pump and when the power goes out. I PUSH 12000 GPH A GOOD BIT OF WATER WHEN I LOOSE POWER the water level drops a good 2 inches " water in motion " untill the level of the pond drops to the rock at the negative edge. Now this is the flaw in my design i have a a 6x6 area about 18" deep and this is just barely big enough if not is undersized, to get the pond up and running when the power is restored. The entire water level in the pond needs to build up that 2 " inches again SO the little pump from the cistern pushes water into the small pool at the base of the negative edge. it takes a little time and the pump draws and spits out a bit of air. If it did this for 20 minutes the pump would probably burn out if it did not have a thermal shut off.
I had planed to draw the water with the 12000 gph pump from the cistern but that didn't work out from the bottom of the pump to the bottom of the cistern is a good 6 feet . External Pumps do not pull water they push water so they have a real problem with trying to pull water up the 6 feet even if the water level is at three feet. so the solution was to put the intake tot he pump in the pool at the bottom of the cistern and have a small pump circulate the water from the cistern back to the pond. i have it dump in the pond right at the negative edge so it fills that little pool as fast as possible. Its for this reason i may not be done with the pond i may enlarge that little pool to an other pond and have it end right next to the bog this way there is only a small lift for the pump of 6 feet. reducing head pressure and distance. i can also have the pump draw from the cistern as it will be maybe a foot or two above the cistern not 6.
 
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I WAS THINKING OF PLACING MATALA PADS UNDER THE BASE BALL SIZED ROCKS IN THE CATCH POOL SO YOU JUST SLIDE A FEW BOULDERS ASIDE AND YOU HAVE ALL THE DEBRIS IN THE MAT
 
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Idk my intake bay pulls all the floating crap into it, which is mostly plants that are getting ripped up by koi and those annoying helicopters seeds off maple trees this past spring. I do have those Aquascape power heads in the pond creating a circular flow near the surface, so surface debris gets pushed in the direction of the intake bay. Will say leaves aren’t an issue with my pond, as none really fall into it. Mostly went with intake bay over negative edge due to the turtles in my pond.

Agree that you can size a skimmer for a large pond, still use a skimmer at the far end of my pond by the bridge to feed one of the bogs. The other skimmer is abandoned at the moment, in favor of the intake bay, but May end up putting a pump of some sort in there if I add another water feature like one of the 4-5’ tall urns…..

With the intake bay as well, you can always add or remove rocks at the weir/entrance to the intake bay to create the desired effect. Ie widening/narrowing the weir, lowering/raising the depth at weir entrance even after the pond is done, if it doesn’t come out how you imagined.
I KNOW your pushing a lot of water. for the most part a 3 or 5000 gph pump i don't see it doing much pulling in from the surface . it will draw from all levels of the water column. i am just saying a negative edge or skimmer suck strickly from the surface where the newest items that fell in the pond can be drawn out the quickest
 
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In one of the videos, John talks about 2000 gallons of water going over the hill if the power goes out. I may be misunderstanding something here but it seemed like in his example the water in motion was from the waterfall and the top 2 inches of water in the pond that would spill over the negative edge. So if the catch area of the negative edge were designed such that, in the event of a power outage, it would fill up with water to a height equal to that of the pond then the top 2 inches of pond water are eliminated from the equation. Thus leaving me with only the water in the water fall to worry about catching and holding until power is restored. Am I missing something? Is there a problem with allowing the the catch area to fill with water when the pumps aren't running other than debris back flowing into the pond? Negative edge ponds have a constant water level but are they designed to be able to hold another inch or two of before spilling there banks? If so then I would guess the pond itself could be the reservoir for the waterfall if pond had enough surface area and the water wasn't too big?
 
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Look at it this way if you have a pressurized 2" line that pushes out 8,000 gph and your spill way " negative edge allows for 2,500 gph to free flow one inch of water over the negative edge then your water level to the pond will rise until the necessary height is achieved to except the amount of flow so you would need three inches in height of water passing over the negative edge to come close to the pressurized water flow from the 2" line that is the water drop of the pond level. but while the power is on it stays a constant. as tot he falls i would make pools in the falls so i did not need to catch that much water from simply a water fall this will also allow for your plants along the falls to survive as they won't dry out. yes there will be some water no matter how you slice it i would just not build one that completely empties out when the power goes down
 
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I have an intake bay with just one aqua block and vault, Pump is 2000 gph, pond is about 1200 gallons, and I actually have a ball valve partially reducing flow to increase head so the pump isn't operating at full capacity, and the intake bay works great, but you have to be on it when you're having leaves fall. I didn't quite realize the toll cottonwood seeds were going to take on the pond. At the height of the season I could scoop out all the cottonwood fluff and an hour later the whole thing would be covered again. But if I had a skimmer they would be clogging up the skimmer so at least I think the intake bay is better in that regard. I agree negative edge would be even better if it's a possibility. I just wasn't up for it when I built my pond.
 
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THeres no perfect this is it ! this is the only way it works !.
 

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