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My new DIY air-lift pond is finally done. Woo hoo!!

Posted by ccoombs1 7B SC (My Page) on
Mon, Nov 15, 10 at 8:05

I started this pond Spring 2009. It's all DIY and I am not as young as I used to be, so it took a while. The beauty of this pond is that while the shower filter and waterfall do have a small pump (1800 gph), the rest of the water in the filtration is not moved with a water pump, but with air. It's called an air-lift system. It works by introducing air bubbles into a return pipe, 5' below water level. As the air bubbles rise, they push a lot of water ahead of it. I have a Dolphin AV-150 (140 watts) air pump on the air lift header and it moves 9000 gph.

The pond is 7' deep with block walls and a liner. The walls are filled solid with concrete and rebar. The skimmer carries water to a barrel behind the wall, and a 1800 gph mag drive pump pushes that water to the shower filter full of oyster shells (to correct my pH/kH problems) and to the waterfall. The bottom drain takes water to the 275 gallon tank, a mechanical filter barrel with matala filter mats inside the tote tank, then to a fluidized filter bed (bio filtration) and finally to the air lift header and barrel and then return to the pond via two 4" pipes located below water level.

The total volume of this pond is 4660 and it will house 5 of my best female koi.

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Follow-Up Postings:

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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Wow, I am having a little pond envy here. That is one sophisticated set up. It is beautiful. I know your fish are going to thank you.

Jenny


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Thanks! I am really pleased with the final result. I am now anxious to get started rebuilding my other ponds to make them prettier and more energy efficient.

Cindy


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

and when you're finished rebuiling your other ponds you are very welcome to start on mine......lol.

Jenny


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Wow... BF and I were just admiring all the hard work you did for this pond. Great job and a lot of work.

Anne


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RE: My new DIY air-lift Question!

Obviously you have some experience with the airlift pumps. Could you tell us something about the efficiencies of the airlift pump.

Cost vs. volume, cubic foot of air vs gallons of water, etc.

ie. sell me a air lift pump.

(That is not a hostile comment, just want to learn about that pumping system.


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Thanks for the nice comments!

This pond has been a real learning experience for me. there is not much documentation out there for using air lifts on koi ponds, although there is a good bit of info for use in aquaculture (usually in raceways and to circulate water in natural ponds, etc). It is a very energy efficient way to move water (which is why it's used commercially), but it does have limitations. Before starting this pond, I had no experience with air lifts. I heard about them and spent a lot of time researching before I started. I wanted to do this pond and see if I could make air lifts work well on a koi pond before I started planning the rebuild of my big pond. So now the planning begins.

Like I said...air lifts do have limitations. I'll outline the pros and cons.

PROS:
2 to 4 times more energy efficient than water pump. In other words, you can move 2 to 4 gallons per watt of electricity than with water pumps. A good efficient water pump will push 16 to 25 gallons per hour per watt. I am getting 64 gallons per hour per watt with my air lift.

Air pumps are much cheaper to buy than water pumps. My air pump cost less than $200, which is less than 1/3 of the cost of a water pump that will move the same volume of water.

Because they use so much less current, it's easier to run them on generators and keep the pond going in an electrical outage, a BIG concern for me since I live on a rather unreliable electric grid.

CONS:
filtration must be designed to reduce restrictions.

Additional large diameter pipes are usually necessary to permit free flow of water.

Only works on a gravity fed pond. The water can be lifted a few inches high to feed a water fall, but more than a few inches you begin to lose efficiency. In my case, I obtained maximum flow by not lifting the water at all, only moving it. Air lift water was returned to the pond slightly below water level.

More difficult to design a working system because there are so many variables, but with careful research it can be done....as I have sucessfully shown.

There is no pump noise, but there is some bubble noise. I need to find a way to muffle that....it bugs me. I think reducing the size of the vents might help.

I think that's about it. If you want to read more on air lifts, here's a link where it was recently discussed on a koi board.

Here is a link that might be useful: Air lift discussion


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Thanks if the economy turns we will be moving back to North Carolina and if we have space I would like to have another pond. I will look into the air pump to see if would fit for what ever conditions we may find.


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

If you can make it work, it's so worth it. I just love thinking about how cheap this pond will be to run.


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Cindy,
The system looks good. Yes can be very efficient way to move a lot of water with very little head pressure. Looking at the pictures it appears that the air is being injected through barb fittings inserted in the walls of the pipes. This is a very simple way to get the air into the pipes. If you build the same system and use air stones instead of direct injection the efficiency will be 2 to 4 times higher with a side benefit of being able to use that air also to run four foam fractionators. But it is more difficult to get air stones in the piping.
Very nice job I just love it when a plan works.
Mike


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Thanks Mike. From the research and experimentation that I have done, large air bubbles work better than smaller ones. As the large bubbles rise, they flatten out and push a huge mass of water ahead of them. Smaller bubbles are necessary in larger diameter pipe, but in smaller pipe (2" or less), large bubbles work better.

I have a running air lift on another pond. I had to use the plumbing that was already in place, which was a 3" pipe. I put a sweetwater air stone down the pipe about 4' and can flow around 2000 gph easily with a AV-50 air pump.


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Cindy, I'm doing this!
Your air in the pipes is 5ft below the water level, but I
can't find what size pipe you are using.
Is that 2 inch or 3 inch pipe?

thank you for taking the time to describe all of your hard
work so well, even I can understand it!

Corrie


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Great Corrie! you will love it. The pipe that feeds the air lift header is a 4" pipe. It comes out of the fluidized bed filter, drops down to 5'below water level, and then the four pipes that actually lift the water are 2" pipes that are inserted into the 4" pipe with uniseals. The air is introduced into the side of the 2" pipes, right where they tie into the larger pipe. Check this thread out....there are lots more details and pictures. Let me know if you have any questions...I'll be happy to help you design your system. It's such a great way to move water!

Here is a link that might be useful: Air lift pond details


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Cindy,
High much above pond level are you lifting the water? Based on your pictures it appears that you have two bottom drains are feeding into the first barrel and then the water is being lifted to the second drum. I assume from there it flows into the pond. Is this correct? If so what is the size of the pipes going from the first drum to the bottom drains? How long is the pipe run on each of these drains. What fittings are on each of those runs? How far below pond level is the height of the water in the first drum?
Mike


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Mike, this pond has one bottom drain. The total distance from the drain to where it enters the tote is probably 10', with 2 - 90° elbows. Water goes from the bottom drain into the 275 gallon tote.

Inide the tote, there is a barrel with matala mats in it (there are dozens of 1" holes drilled around the top perimeter of this tank to permit only top water to go in, not water that has settled out stuff). There are two 4" pipes going from that barrel (no 90s, just a straight run of pipe maybe 18" long each), through the tote wall and into the fluidized bed.

Inside the fluidized bed, there is a 6" slotted pipe (the green one) so the water flowing in through the two pipes are pretty unrestricted. From this barrel, there is a knife valve and a 4" line (with two 90° elbows) that comes out and turns down, to drop 5' below water level. The four 2" lines come out of the 4" and lift the water up into the return barrel.

The water is not being lifted at all, only moved. The top edge of the 2" pipes are located right at water level. There are two 4" pipes (each with a single 45° elbow and a 90° elbow) about 12" below water level that return water to the pond.

The water in the first part of the filter (the tote) is drawing down about 2 3/4" below full when I turn on the air pump. There is about a 2 1/2" drawdown in the second barrel (the fluidized bed) and the return barrel (the air lift barrel) is about 1" above water level.

I know there is a way you can determine flow rate with this information but I don't know how to do it. I hope you do!

Here's a schematic of the filtration, if that helps any.

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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Cindy, fantastic! Nothing like a visual aid! You designed a great system, I like everything about it.
I'll take you up on that offer when I start digging, it'll be fun.
Thanks again
Corrie


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Cindy,
I would say you did an excellent job in designing and building this filtering system.

Yes I can calculate the flow rate based on water level differences and length of pipe. There are two places where I could do these calculations with your system. The first place is from the bottom drain to the tote. The problem with this measurement I don't know how accurate your measurements are and would have to be taken in the first chamber of this filter. Then there is no way to know the friction of the media in the first chamber. So I do not know how accurate my calculation is here which is 5579 gph flowing through the bottom drain. So I question this number. The idea place to measure this system is on the 1" of head pressure on the last drum. But I have a couple of questions here. That 1" above pond level has to be as accurate as possible as we are talking about very little head pressure. Secondly you told me that you have a 45 and 90 on each of the 4" return lines from this drum but how long is the 4" pipe from drum to pond? How does the piping go through the pond liner? The more accurate all this measurements are the more accurate the flow calculations are.
The reason I can't use the middle drum measurements is that the 2 four inch pipes are capable of delivering far more water then is needed by the flow of the air lift. I can tell you that the water level in the middle drum can't be any higher then the tote. So if the 2.5 inches is correct then the flow rate would drop to 5287 gph.
You say you have no lift over pond level with your air lift system but actually you. Because the lift is from the middle drum to the last drum so the water level is the height of the middle drum verses the last drum which is 3.5 inches.
Mike


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

I'll get some more accurate measurements, but the last barrel is really close to the pond wall and the pipe basically just leaves the barrel, goes through the 45 to straighten it out to run parallel to the wall, then 90s through the block wall into the pond. I used the "pipe boot" method to get the pipes through the liner. Cheap, easy and no restrictions. One section of pipe is no more than 4', the other is less than 3' (probably closer to 2'). One thing I forgot to mention is there is a fernco coupling in nearly every 4" pipe run, but I doubt these affect flow.

To guard the end of the pipe, I split a piece of vinyl tubing and fitted it over the end of the PCV. Then I fitted some sections of 3/16" stainless rods through the inside edge of the tubing. Once it was done, I glued the whole thing together and on to the end of the pipe with that black poly sealant stuff. I doubt this restricts the flow much, if any.

You know....I just read back through this thread and realized I didn't update the results of an experiment. Because I didn't want 9000 gph, I tee'ed off some of the air to the fluidized bed. My new measured flow was 5400 gph, which is the flow where my draw down measurements were taken. So your calculated draw down is extremely close to what I measured.

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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Cindy,
I like your home made grates for the end of your return pipes. I will have to remember that those in case I ever need something like that. I would do away with those but they do add friction to the flow of the system. Since these are DYI there are no exact measurements on these but I would guess that they are the same as 6 ft of pipe. So let's calculate the friction on your return lines. First we have water going from the drum into the 4" pipe. So we have 4 ft of the diameter of the drum and 2 ft of the 4" pipe for water to move from a larger pipe to a smaller pipe. The drum is large enough that four ft of it won't amount to any friction to worry about. But the 2 ft of 4" we will look at. Then we have a 45 elbow which is the same as 5 ft of 4" pipe. Then we also have 90 elbow which is the same as 12 ft of 4" pipe. Then we have the Ferco fitting. I am going to assume that the pipes inside the Ferco fitting are tight against each other and are in a straight line and this is the same as 4 ft of 4" pipe. Then we have the pipe expanding in the pond and this is 4 ft. of the 4" pipe and 2 ft of the diameter of the pond which will be about nothing. Then we have a 4 ft of pipe and a 3 ft of pipe. So each of the return lines are as follows: 6+2+5+12+4+4+4+3=40 ft of 4" pipe. So that short length of 7 ft of pipe is actually with fittings and changes in pipe sizes equals the same as 40 ft pipe. So the question is how much flow do we get by gravity through 40 ft of a 4" pipe with 1" of head? We actually get 3146 gph per return and we have 2 returns so the actual flow back to the pond would be 6292 gph. But I would guess that the head pressure is less than 1" so if I look at .5" head pressure we have flow for each return of 2156 or a total flow 4312 gph. So I would guess that when you actually take a good measurement of the head pressure you are going to find that it is a little more then .75 inch. .75 inch would have a flow of 5302 gph.
Mike


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RE: Correction

Cindy,
In my last post I left out the word "not" in the third sentence. So the third sentence should read "I would not do away with those but they do add friction to the flow of the system."
Mike


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Thanks Mike....I was so unsure for a long time how I would handle those pipes returning into the pond in such a way that the flow would not be restricted and that the koi could not be injured. This was the best solution I could come up with.

And thanks a lot for explaining the calculations. That makes thing much clearer! I guess the most important measurement I can get then is the amount of head that is on that return barrel. I know that before I diverted some of the air to the fluidized bed, the return barrel was overflowing. Not bad, but I there was a steady trickle of water flowing over the sides. Now there probably is an inch although it may be a bit less. I'll try to get that measured very accurately soon.

In hind sight, I wish I had set that return barrel about 12" higher. As it is now, there is not much room for error. If a return line gets blocked, the barrel will overflow. I will replace that barrel in the spring with a new one and set it higher.


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Cindy,
To get the flow back up to 9000 gph the last drum the water level will be 2 inches above pond level. And of course there will be some wave action which will bring some points higher and some lower. The water level in the tote will drop to 6" below pond level and the head pressure the air lifts will see will be 8" of head which is getting pretty high for air lifts. The speed of the water moving through the bottom drain pipe will be about 2.6 mph. What you have to be concerned with is the solid waste from the fish breaking up. At that speed it is border line with a straight pipe but with the elbows there is going to be break up at each elbow. How much will actually break up I do not know as that would be determined by a lot of other factors but it would not surprise me if it was 50 to 60%. At 5400 gph that speed drops down to 1.57 mph and I would guess the break up fish waste would be 10 to 15%. The only problem with this speed a little of the heavier objects may fall out of the water column at the first elbow. How much of this will happen will be determined by the design of the bottom drain that you used, the debri in the pond and algae in the pond and drain.
Now looking at your drawing of your tote the question becomes how good is this design at separating solids from the water column. The drawing is pretty small and I don't know how close to scale it is I can see how it could be very good. The question I have is where the 4" pipe goes into this tote how far from the center drum does the pipe end? Is this pipe aimed at the drum? If so where on the drum does the water hit the drum? Then the next question is how large is the drain on the tote? Is there anything that brings the fish waste to the drain?
Mike


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Mike, that's one reason I wanted to slow the water down. There was a great deal of turbulence in the tote and the water was slamming right into the barrel. I added another 90 so the water comes in to the tote and is directed up instead. I plan to add a leaf net to catch the leaves. The drain on the tote is only 1 1/2" which won't handle leaves at all. If I had to do it over again, I would not use the tote. I'd get a water tank from tractor supply and use that instead. I'll do that when I rebuild the new pond (probably use a 1500 gallon water tank on that pond). I know that to be effective settling, I should have more like a 450 gallon tank instead of this 275 gallon one. The filtration has been running for a week now, and there is a great deal of settled debris in the tank and a fair amount of stuff in the matala mats too. So it is settling out a good bit. The water is not clear, but it's improving. There are two koi in it and I can see them when they are in the bottom, although not well. Mostly just see their colors.

The barrel inside the tote has a knife valve so I can drain it into the tote for cleaning. If you'd like, I can send you a PDF version of the drawing but I can't do it until next week because the autocad drawing is on my computer at work. The size of the containers is to scale, but the runs of piping is not.


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Cindy,
For a SC to work correctly by gravity alone at your flow rate it would have to be a min of 1700 gallons. That isn't going to happen so to get a smaller SC to work we have to force the water to make a sudden change in direction. By getting the water to make a very quick and sudden change in direction the water comes to a stop and then starts in another direction. This causes anything in the water column to drop out. The way I would do this in your situation would be to put a 45 elbow on the 4" bottom drain line. The elbow would be parallel to the bottom with the water going in a counterclockwise direction. Then a wall would be installed as close to the drain valve as possible but just past it. This wall would go from the outside wall of the tote to the center drum extending from the floor to about 2/3 as tall as the water in the tote. Most of the debri will drop right at the base of this wall so that when the drain is opened the debri will flush out.
Yes I would like a PDF of your filtering system.
Mike


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RE: My new DIY air-lift pond is finally done. Woo hoo!!

Cindy,
Not sure if you check back at your old threads but I came across this toady researching air pumps to use with a koitoilet bottom drain with the air defuser. I am very interested on how your system has been performing the last 2 years. My SC will be 4'x6' with a water depth of 3'.


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