Pond Boss Forums AERATION Systems questions Pump application instead of aeration

I bought my .4 acre pond at the end of last June and the only circulation was created by a 1hp torpedo pump fountain in the center of the mostly circular pond. My plan is to get rid of the fountain for multiple reasons. The first reason is esthetics. I just don't like the look of a fountain. I feel it takes away from the serenity of the area. Second, I want to avoid the massive amounts of water evaporating in the hot summer months and avoid watering the lawn whenever we have wind. I also feel that it is very inefficient for water turnover.
So here is my plan; I have a dock area at the deeper end of the pond where I have my power run. I will take the torpedo pump and station it on one of my dock poles a foot or two from the surface. I will then run a combo of flex and ridged 2 inch PVC to 3 areas of the pond. One in the deep center with the majority of flow and 1 in each of the shallow horns at the other end getting less flow. All will be elbowed toward the surface with a head design to pull more water around the pipe to join the stream upward.
Next, I plan on adding a second pump in the same area later and elevate the flow up a hill and create a stream into a shallow area at the other end of the pond. Once I do this, I will remove the shallow discharge from that area and move that flow elsewhere. I feel this should give me adequate surface area turnover and little evaporation and water loss. It also should look great, as the pond is the centerpiece of my back yard. I would love to get some feedback to my ideas. Maybe things I may be missing. I also wonder why I have not found more people using pumps in this way.

This is what I plan on putting at the ends of the pipe at the bottom of the pond. They are called eductors. They use a Venturi effect to draw outside water to be drawn into the bottom of the nozzle. This creates a greater flow rate than just the pump alone can produce. It also allows bottom water to be mixed with the water from the area of the pump. Although I plan on building my own.

Till the experts give you a real answer, I will relay my limited knowledge that has came mostly from reading, not practical application.

Lots of people use an air pump to move the water instead of a water pump because of the energy used. Pumping air down and letting the bubbles do the work seems to be pretty energy efficient, as in low electrical bills. In reasonably deep water that is. At least that is the theory.

What you are doing sounds like it would work to me. In farm sprayer applications there is a thing called an agitator or sparger that fits in the bottom of a farm spray tank. It uses a vortex to gather in surrounding liquid and use the stream of liquid coming in from the pump to agitate the tank. These might work very well for what you are trying to do. They are plastic and fairly inexpensive. Here are some examples: agitators

My only concern would be to make sure any flow does not stir up the bottom muck and make the pond a muddy mess. So just watch where you aim water flow.

Good luck and if you proceed with your plan, let us know how it works out.

Edit: I see you beat me to it. You posted a picture of what I was talking about while I was composing my post.

I figure if I place the elbow of the pipe up through the hole of a concrete block and add the eductor above the block then it can't fall over and can't pull mud off the bottom.

As for your explanation about why aeration over pumps snrub , aerators have to push air down to the bottom against back pressure caused by the waters depth before it can start floating back to the surface. This makes an air pump work harder as it gets deeper. This is similar to a water pump pushing water up hill. I don't know what that costs in electricity for aeration, but when you have a submersible pump that is only pumping under water, it has very little head pressure due to only the pipe's constrictions. This means it usually consumes less electricity for a greater water output. Not to mention, instead of just pulling one column of water from the bottom with aeration, I can move surface water from one side of my pond to the other while mixing both surface and bottom water. I would guess that is much more efficient. I am also a fan of quietness and in my experience, piston air pumps are not very quiet. On the other hand, submersible water pumps are generally very quiet. Now this is all deductive reasoning from my aquarium experience and I have not used these applications in ponds so if I'm wrong here please set me straight.

Give me some numbers and I'll do the comparison for you. i.e. hp of the pump and gallons of water moved to come in contact with the air.

OK, lets say I have a 1hp pump that is pushing 6660gph at 10ft head pressure drawing 7.3 amps (900wt) at120v. I say "let's say" because I can't find my exact pump and this is the closest specs I can find on the net. Also remember that there will be much more water movement than your gph because when under water you are dragging more water along with the column of water that the pump is producing the same way that air drags water as it rises to the surface. As i stated before, i am also moving the water from one side of the pond to the other, which an air compressor cannot do. This allows for your flow rate to move surface water back to the pump on the other side of the pond creating a larger loop of water movement. Also, you can't really compare direct water movement (gph) to cfm of air discharge as different Diffusers and other variables will change those numbers. Not to mention that you are not comparing the same thing. Is there a conversion between gph and cfm? I'm not trying to be difficult here, I'm just trying to figure it all out and this is how my brain works.

I know this is kind of a sidetrack and probably won't help you out, but you might be interested in this LINK to water flow and current in a pond. Tum's has a very unique situation with his pond.

Wait until you see the comparison from Esshup on using air vs. your pump. I think you'll change your mind. Air can move a lot of water much, much more efficiently than a pump can. That's why it's being used to destratify ponds.

We're talking up to about 3000 gallons per minute of water movement with for example a vertex air station at 1 cfm at a depth of 12 feet, which comes to to 4 million gallons of water turnover per day per diffuser. Try doing that with a pump!

And no I'm not in anyway plugging Vertex and have no dog in the hunt but used that as an example.

Our European counterparts are moving up to 66 gallons a minute using a linear air pump that uses only 10 watts of electricity in their koi ponds!

I read that link and some of the one at the end of that one and both went off topic a lot. Seems like horizontal aeration via pumps can be used with success, but what I'm proposing is kind of a combo between vertical and horizontal. I think it should work well for me.

You might be trying to reinvent the wheel. Just saying and please don't take offense.

No offence at all. Reinventing the wheel isn't always a bad thing. Could you imagine if we were still using stone wheels on our performance cars instead of aluminum alloy and composite rubber? Just because it works doesn't mean it can't be improved upon in certain ways and applications. My background is in saltwater reef aquariums where we are able to keep animals now that were thought to be impossible just 10 years ago all because of people reinventing the wheel. If you are not pushing the boundaries and learning new things, why bother? Just my opinion.

Isn't there a difference between perfecting the wheel vs. trying to reinvent it?

I'm not an any way saying that air pumps and diffusers don't have their place and aren't better in certain applications. That being said, where do you get these numbers? The manufacturer or independent study? You are also comparing apples and oranges. As all variables on both sides are not included within the same application. I'm not trying to be argumentative for just the sake of argument. I'm just looking at it in a very strict scientific way. If there are independent studies to compare total water movement in a closed, controlled environment between the two, I would love to see it. I have an open mind and I couldn't care less which is "better" I just don't take someones word for it when numbers are being thrown around. Like you said, please don't take offense, only a conversation.

Touche.... in that case, no, I'm not reinventing the wheel.

No offense taken. And I too don't take numbers at face valve, but I know one of the sources personally and he's a person of high integrity and he wouldn't just throw some numbers out there.

As far as the data for the 10 watts producing 66 gph per hour (15 m3) it's there but you have to be fluent in Dutch to read it. Fortunately I know an individual that is and he assures us that the numbers are correct.

Have a diffuser/compressor system myself and having seen the boil and air that comes up from just one diffuser at 1 CFM it's entirely believable that much water is being moving.

I guess my point is there's no doubt that rising air can move water more efficiently than a pump. It's scientific fact. And it's common sense if you see both in action.

I never intended this post to be a pump vs air compressor thing. I am using the pump in this fashion strictly because I already own the pump and I wanted to derive a way to use it so that it gives me the best results for what I have. Besides, I really don't like the noise or the unnatural look of the boiling effect that air gives. I was just more or less curious about why I couldn't find more people using pumps in this way over other applications. I'm not all that surprised that compressors are more efficient, and I'm sure that it is even more so for larger bodies of water. It does seem to me that they do have their limitations in their usage, especially in smaller ponds. I guess I will just keep people posted as to how it works out for me.

Otter, here's some numbers for you to crunch. I sell Vertex systems, and I'm using their figures because that's what I have.

I'm not saying one system is better than the other, or that you can't do what you want to do with your system; I'm just throwing this out there for energy use comparisons. It's just more effecient to move water with air if the sole intent is to destratify a pond, and to get O2 into the water. If the pond is shallow, or there is a high oxygen demand, also look into surface agitators. If I was trying to keep high O2 levels in a pond, or had a pond where it had high O2 demands, and I wasn't concerned about warmer water (say a LMB/BG pond vs. a trout pond) I'd run both a bottom diffusion system AND a surface agitation system. If the pond was under 8' in depth, I'd concentrate on the surface agitation systems.

Here's the numbers:
I'll use a max depth of the pond at 10' because that equates to 10' of head pressure like you used in your example.

Using a 1/4 hp air compressor, with the diffusers set at 10' depth, a 2 disk diffuser station will move 3,200 GPM.

"I was just more or less curious about why I couldn't find more people using pumps in this way over other applications."

Energy efficiency. That is mostly the answer. Especially as water depths get deeper than 9 or 10 feet. For a person starting out with nothing, the money to buy the equipment and the monthly operating costs are likely to be cheaper for using an air pump specifically designed to aerate ponds. Waste treatment systems also use the same types of systems for the same reason.

I'm all for trying to use what a person has though, and obviously you have been happy with whatever your electric bill has been (with the fountain), so that is not an issue for you. Should be no higher electric bill than you had before operating the fountain.

Keep us informed how your system works after you get it done (and even while in the process of making it work). We like pictures also, if you have the time and inclination.

I think your pump will work fine. It might or might not work as well as another different type system, but it should do what you are attempting to do with it and give you the results you desire in comparison to the fountain you had. That is what is important.

I'm no expert at this, by any means. But I can tell you I have read a lot of the archives and there are some good old threads that talk about the advantages of moving water with a water type pump instead of air, and where they excel and how they are best used in the applications where they work best.

Good luck and keep us informed.

Otter25rs,

My apologies if I misdirected your intent. Please keep us posted. We are always open to new ideas, I know I am even if I didn't seem like it.

So what is the daily or monthly energy consumption on something like this using say $.12/kwh

Ballpark $33/month average.

calculator

And that's 3000 gpm vs. 110 gpm?

Assuming 24h operation for the pump it looks like $73/mo. at $.12/kwh.

Bottom line looks like about 50-60x greater cost per unit of water moved for the pump vs. the compressor.

In a year of continuous operation you might save $500 to use the compressor. In four years it's possible you could have justified a brand-new purpose-built compressor plus lines and diffuser stations.

Ok, I get that Air pumps are more efficient at moving water, but in my opinion we are not comparing correctly. If someone figured out that an air compressor moves 3200 gallons of water that's great, but that water can only be moved upwards from the bottom of the pond. I would guess that a good portion of that oxygenated water gets pulled back down immediately to be pulled back up without helping to circulate new unoxygenated water. So some of that lifted water flow is useless. Also, you are limited to a certain diameter of flow from the center of each diffuser. As you get farther away, the less water is moved and therefore oxygenated. This makes it necessary to need multiple diffusers to prevent dead spots towards the outer shallow areas. This is not an issue if you are strictly destratifying the water, but it is less effective for oxygenating the entire pond. The only way you can compare a pump in the same fasion is to set it on the bottom attached to a pipe that stretches to the surface. That is how the pump is rated in GPH. If you remove the pipe, the water flow increases considerably because it is dragging surrounding water with it to the surface. Add the eductors to the pump and you increase the output even more.
Now, if you use a pump to pull oxygen rich water from the surface of one side of the pond and move it via pipe to the bottom at intervals across the ponds bottom to the other side you create a current that includes the entire pond and oxygenating all areas. This is because that the water has no choice but to travel back across the pond to the pump. This means that you are now moving the entire ponds volume of water not only vertical, but horizontal and oxygenating the entire pond in the process. You would not be pushing that water as fast, but you are utilizing the flow rate in a more efficient way.
Food for thought.

Otter,

I do kind of question the impeller versus air myself. I'm not sure how pump loads are tested for this purpose, but one would think that when run in a circulatory capacity the load would be very low. You don't really have to "lift" anything you just have to move it. Pumps are typically thought of as moving water against a load or restriction and lifting in the atmosphere.

The key points would be plumbing size, complication, and having electricity in the water.

I wondered about taking (one for starters, possibly several) small 12v pumps (battery with solar collector) that move approx. 5GPM ea and run submersed to see what it would do. I think a guy would want the discharge into a fairly larger diameter pipe that extended to near the surface and possibly some sort of diffuser to spread the discharge.

I still don't think it would match the air pump, but it's intriguing.