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Joined: Oct 2024
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OP
Joined: Oct 2024
Posts: 3 |
Hi All,
This is my first post. What an awesome resource you all are. I'm trying to size a recirculation system, and would love your advice.
Our farm has just combined 2 small ponds into a single 1.75 acre pond. 3:1 edges down to 15' with a range of depths and topography, as well as an island, stone humps for structure, a couple of flats and channels at various depths, etc. We think it is around 2.75mm gallons. The goal is to have a great conservation, fishing and recreation resource, and have it be pretty and pleasant to be around. The clearer and cleaner the better.
The pond is fed by springs, as well as surface water. The surface water runs through a swale, into a forebay, and then over a stone sluice, where the water falls into the pond. In drought, like now, there is no water flowing in the swale, but at other times, it flows. We are planning a recirculation systems, where water will intake at the end of the pond farthest from the forebay, and then be pumped to a high point in the swale, then run down to the forebay, spill over the stone sluice, and fall into the pond. The question is how many GPM should that be?
If I did the math right, to totally turn over the pond in 24 hours would be 2000 gpm! That seems excessive to me. And I don't want to have an electric bill like a water park! At what level of GPMs are we having a noticeable impact on the pond health? (In the past, the two ponds had no recirculation, and we definitely had some algae, we tried to manage w/ a straw program with mixed results). We could put in air defusers in the future as well, so we don't need it to be perfect at the outset, but we don't want to put in a system that has no impact.
We'd like to figure it out soonish, so we can chose the intake pipe size and get it installed before the pond fills up.
Love to hear everyone's opinions on the matter!
Thanks!
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Joined: May 2004
Posts: 14,240 Likes: 371
Moderator Lunker
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Moderator Lunker
Joined: May 2004
Posts: 14,240 Likes: 371 |
Your Math works out.
What made you choose a recirculating system over aeration? It is cheaper and easier to move air and have the air move the water.
P.S. Wingdale, NY?
"Live like you'll die tomorrow, but manage your grass like you'll live forever." -S. M. Stirling
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Joined: Nov 2007
Posts: 4,128 Likes: 749
Lunker
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Lunker
Joined: Nov 2007
Posts: 4,128 Likes: 749 |
There are basically three things that make your pond water turbid (unclear).
1.) Briefly suspended inorganic material.
This is the silt and other debris that enters the pond after a big rain event. The pond should stay murky for a few days and then clear up slowly. Your swale and forebay should lessen this effect to some degree.
(One exception to "briefly" is if the pond contains carp, bullheads, etc. that stir up the bottom sediments when their population exceeds their food supply.)
2.) Long-term suspended inorganic material.
Some types of clay minerals can create tiny charged particles that remain suspended in the water column of a pond. These do NOT settle out in reasonable time frames. Generally, a treatment of the pond water must be performed to alter the chemistry and cause these clay particles to flocculate and settle out.
3.) Suspended organic material.
A healthy pond will have plankton blooms that will make the water cloudy. These can be either phytoplankton (photosynthesizing organisms) or zooplankton (tiny animals). These organisms are the critical base of the food chain. If you make your pond crystal clear all of the time, then your fish populations will suffer to some degree.
I don't think recirculation by itself would really address ANY of those three types of turbidity!
However, I think you may be able to significantly effect suspended organic material (#3).
If your new pond was created by combining two relatively old ponds, then your pond basins are probably going to be fairly nutrient rich. The phytoplankton in the pond are going to be constantly working to utilize these nutrients and grow their numbers and density.
I think you should do an internet search for "living pools". These are pools or small ponds that use aquatic plants to filter the water and sequester the nutrients themselves and "steal" them from the phytoplankton that make ponds murky.
This concept might make your pond "prettier and more pleasant to be around". I say this because you already have the forebay and stone sluice installed. Those are the the biggest costs by far!
If you like the "living pool" concept, then I would research which plants you want in the forebay. I would select plants for your climate zone, plants that you find attractive, and plants that do NOT spread by floating seeds or plant fragment migration. (You want your water lilies, etc. to stay in your forebay and not spread into your main pond.)
In that situation, I doubt your water recirculation rate would be your limiting factor. I suspect your limiting factor will be the "take up" rate of nutrients by the plants in the forebay. If that is true, then you could design your pump to meet that rate, plus whatever excess water flow you desire to make the waterfall going over the stone sluice look attractive.
Good luck on your new combination pond!
I am just throwing out some ideas for you to consider as you look upon your actual situation.
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Joined: Jan 2009
Posts: 28,928 Likes: 975
Moderator Ambassador Field Correspondent Lunker
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Moderator Ambassador Field Correspondent Lunker
Joined: Jan 2009
Posts: 28,928 Likes: 975 |
Welcome to the forum! Typically with a bottom diffusion aeration system, you want to bring 100% of the water volume of the pond to the surface a minimum of 1 time every 24 hours, 2x is even better. With 2,000 gpm, that's 23 hours of running. Now, what hp motor/pump will it take to do that? If you use a properly designed bottom diffusion aeration system, my SWAG says you could achieve that with a 3/4 hp rotary vane compressor. 15' max depth is approximately 8 psi. Now I am not saying that one air station will do the trick, but you can look at this chart and see how many air stations you will need. One diffuser disk will need 1 cfm of air. If you want, PM me the address or email me a sketch of the pond with depths and dimensions. I could figure out a bottom diffusion system for you (from Vertex). You would then just use the 2000 gpm pump for mostly aesthetic reasons. You can see by the lifting rates on the chart that one diffuser disk, at 14' water depth will move over 2100 gpm to the surface. That could be accomplished by a single 1/4 hp compressor, but due to the sphere of influence that a single diffuser disk has, your pond needs more than 1 diffuser disk in one spot.
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Joined: Oct 2024
Posts: 3
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OP
Joined: Oct 2024
Posts: 3 |
Hi all. This has been super helpful already. Thank you!
It sounds like the headline is that we should size our intake pump and recirculation to keep the waterfall/swale as a nice water feature (with some incidental water quality benefit) and so we have adequate water for farm irrigation. Then we should do the bulk of our water turning with an air pump and diffusers.
Quick follow up questions:
1. My understanding is that is is pretty easy to add the diffusers once the pond is full. Is that right? My hunch is, due to shape and where deep areas are, we'd want 3-4 diffusers.
2. Is it a problem if we have the diffusers on a timer to be off during the day and on at night, so that they don't change the experience of the pond for folks during the day? We could oversize them to turn the full pond volume each night.
Thanks!
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Joined: May 2004
Posts: 14,240 Likes: 371
Moderator Lunker
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Moderator Lunker
Joined: May 2004
Posts: 14,240 Likes: 371 |
1. My understanding is that is is pretty easy to add the diffusers once the pond is full. Is that right? My hunch is, due to shape and where deep areas are, we'd want 3-4 diffusers. Correct. Adding diffusers post-fill is pretty easy. Bite the bullet and get sinking airlines; you'll be glad you did, short term and long term. You probably want a diffuser for each deep hole, and possibly other places depending on pond shape. if you post an aerial photo, we'll be glad to give our $0.02 worth on placement. 2. Is it a problem if we have the diffusers on a timer to be off during the day and on at night, so that they don't change the experience of the pond for folks during the day? We could oversize them to turn the full pond volume each night. A timer let's you customize aeration hours for all kinds of reasons. I run my air pump on a 24 hour timer, and adjust the number and schedule of hours it is on depending on the season.
"Live like you'll die tomorrow, but manage your grass like you'll live forever." -S. M. Stirling
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1 member likes this:
FishinRod |
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Joined: Oct 2024
Posts: 3
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OP
Joined: Oct 2024
Posts: 3 |
Thank you! this is very, very helpful. I'll let folks know where we land, and may reach out for ideas about placing diffusers in the future. Much appreciated!
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Joined: Jan 2009
Posts: 28,928 Likes: 975
Moderator Ambassador Field Correspondent Lunker
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Moderator Ambassador Field Correspondent Lunker
Joined: Jan 2009
Posts: 28,928 Likes: 975 |
2. Is it a problem if we have the diffusers on a timer to be off during the day and on at night, so that they don't change the experience of the pond for folks during the day? We could oversize them to turn the full pond volume each night. It won't be a problem IF the system is designed to turn 1.5 times the complete water volume of the pond the length of time that you want to run the system. It will be a problem if you buy a system that is designed to run 24/7 and only run it less than that.
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Nutria
by J. E. Craig - 12/03/24 04:10 PM
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Koi
by PAfarmPondPGH69, October 22
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