Flow Rates and Airlift Pumps | Ask The Aquaponics God

Flow Rates and Airlift Pumps | Ask The Aquaponics God

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  1. Could I hire you to help me build a system on my property. I know the basics and how to maintain things but I'd like some help designing the whole thing as ideally as possible from the jump and I'm just not experienced enough for that.

  2. @9:09 you state that "you can't go any more then that." I disagree. (I love your vids btw) Pumping and the costs associated with pumping are a function of flow rate and discharge head. Now with low pressure pumps, like aquaponics uses, frictional losses are VERY VERY important since as the frictional losses build throughout the system they substantially decrease the actual flow rate of the pump. For gravity flow systems with modest elevation drops (which should be a design goal for an efficient aquaponics system) a target liquid design velocity of 3 – 4 ft / second is reasonable, especially in small to medium bore piping. The larger the pipe diameter, the greater the target design velocity can be. This is because of the ratio of the wetted distance of the pipe (circumference) to flow volume decreasing by the square of the pipe diameter. (2 * PI() * r) / (PI() * r^2) For large pipe like 10" it is appropriate to use a target design velocity of 8 – 10 ft / sec and for very small pipe 1" or less you should be using values like 1 – 2 ft/sec design velocity. Knowing your flow rate and your target design velocity you can size your pipe using dimensional analysis. Therefore @ 7500 gallons / hr and using 4 ft / sec target design velocity you get a 3.57 inch INTERNAL pipe diameter which would lead to a 4 " schedule 40 PVC pipe and for 1849 gallons / hr you get a 1.89" ID requirement which would result in a 2" pipe. For PVC pipe dimensions you could use a website like and to calculate the required INTERNAL diameter knowing your flow rate and a target design velocity you can do your own calculation as I have shown below or use a website like I HAVE NO AFFILIATION WITH ANY WEBSITE LISTED, JUST USED AS EXAMPLES.

    1849gallons/1 hour * 1sec/3.5 ft * 1 hr/60 min * 1min/60sec * 1ft^3/7.48gallons * 144in^2/1ft^2 = 2.825 in2 which is the cross sectional flow area that is required. Then we can convert this to the diameter D = 2 * (Area / PI())^0.5 = 1.8966 inch INTERNAL diameter. You will need to iterate to a solution if your target design velocity is inappropriate for the calculated INTERNAL pipe diameter by changing the design velocity and recalculating.

    So a flow of 1849 GPH should be done in a 2 inch schedule 40 PVC pipe and a flow of 7500 GPH should be done in a 4" schedule 40 PVC pipe. These are in fact calculable values. I hope this helps everybody and if it does please give me a thumbs up. Thx

  3. I don't think you gave airlift maintenance a fair shake. You leaped from "proper maintenance" to "you are a maintenance man"
    I think you would be justified to say the amount of maintenance is an unknown. And it is perfectly fine to stick with a well known, working system.

  4. There are some great comments here. 🙂

    Whatever pumping method you choose, I highly recommend considering redundancy. Divide the work among more than one pump so that the failure of one pump doesn't mean a crashed system and dead fish.

    For example, if you were aiming for 60-90 minute HRT, you could install three pumps that can each handle a third of that. With all three running, you have 60 minutes, but if one fails or you shut it down for maintenance, the system is still getting at 90 HRT.

    Put another way, say you had a 9000-gallon system. At 90 min HRT that's 100 gallons per minute (gpm.) At 60 HRT that's 150 gpm. It is far better to install three pumps that each can move 50 gpm as installed (at the outlet.) When all three are going, you have great flow. When one is offline, you still have adequate flow.

    When doing this, make sure you consider the plumbing so that you don't create a loop of water flowing in reverse through the disabled pump. You can go with check valves, but there's another maintenance and failure point. I prefer to simply run each pump's output independent of the others. Also, air-gapping the outlets above the tank is a simple way to prevent back-siphon issues without the issues of air admittance holes/valves. Putting that together, running a single pipe from the outlet of each pump to a point above the tank is the least maintenance and most reliable layout. Add true-union ball valves either side of the pump as necessary so you can remove the pumps for service/replacement.

    It is true that three 50 gpm pumps have a higher capital (acquisition) cost and slightly higher operating cost than a single 150 gpm pump, but what is the cost of a tank full of dead fish? Every device in your system will fail. Murphey's Law says it'll happen when you're out of town on vacation too. Taking the time in advance to design it so that the impact of that failure is minimized is worthwhile.

    Apply all of that to air pumps and the air plumbing if doing an airlift system.

  5. It all depends. You can blindly set up a system and make it work easily by forcing water to go where you want it. There is no denying the versitility of regular water pumps. If your system is designed for an air lift where head height is neglibible, then, with the right pump, you can efficiently shift large amounts of water reliably. They have advantages such as debris being able to pass through them. Fish passing through them unharmed and compressed air fed to the pump via hose negating the need for electricity in a wet area. I would urge anyone designing a system with negligible head heights to experiment. The sheer volume of water that can be moved watt for watt is impressive. (I will be posting some vids on the pond I'm building using an air lift pump soon. I don't expect any air lift pump naysayers will be commenting except to say I'm cheating somehow.)

  6. I have a basic chop system I just set up made from ibc totes the fish tank is roughly 150 gallon and 50 gallon sump the grow beds are 4×4 and flood 6 inches deep I plan on putting ten koi fish and a few placo in the sump is a 400 gallon per hour pump pumped in from a 1” pvc and the overflow (stand pipe) is 2” and the pipes to the grow bed is 1 1/4 “ everything I flowing good I have good water pressure just having some difficulty managing my flow rate to the grow beds I am trying to have it fill and start draining around 12-15 min any tips or advice is my pump to big and how often should I circulate the water

  7. Hi, I set up an aquaponic system with 12 grow beds, 6 on each side in the greenhouse. Water is pumped from my fish tank to the grow beds but I need the grow beds to fill up with water at the same time, so same water flow and filling speed which I am struggling to get. I have a 18000l submercible pump that pump the water to a 'power shower pump' speeding up the flow but they are still not filling at the same time, the taps are in 2 lines with 6 on each line and the first tap always get more water faster than the rest, any advice how to feed the grow beds with water at the same time?

  8. Sigh.. I think I spent too much on PVC and fittings. Should have just got the a water pump for the job. Thank you for the well researched video and providing clear pros vs cons. There are many videos providing just the pros.

  9. Hi, Mr.god of aquaponics…its been so much interesting to see all of ur videos and believe it or not ive gained so much knowledge….
    Now coming upto the point…..i want to set up an aquaponics system in which i raise the fish in an IBC and from that, i plan to transfer it to a sump tank which is at the bottom after it reaches a particular height and is supposed to flow freely due to gravity…where i plan to remove the solid waste using a small partition… from this sumptank…i plan to pump the water upto 8-9 feet…from there i thought of using a split system to seperate it into 3 ways…one goes to the centre nft system below which i have a dwc system….the other split goes to the left where i have several vertical system below which i have a growbed system….similarly, the 3rd split has the same thing…..a vertical system below which i have a growbed….so after the bell siphons takes on from both the left and the right ways, i combine them to the dwc outlet and drain it back to the ibc straight away, making sure that they r in a suitable height so that the gravity does its job… my questions

    Is this system viable?….is there any flaws that can be corrected?….anything that i didnt convey properly?
    What if, i want to make it off the grid?…what motor should i be using so that it takes less current and at the same time pumps to that height properly….what solar panel should i be using and how much battery should it have to make the pump work both in the day and all nyt long?
    Is employing led lights at the nyt going to improve the growth rate considerably?…also some say to use different colours for different sizes…can u pls clarify that?
    Is there anyother parameter to watch out for or include if i plan to monitor the ph, temperature and feeding the fish automatically using my arduino automatically

    P.S…thanks a lot for ur valuable videos

  10. best airlift design . search for ————> (olomana garden airlift )for demonstration. its always good . I even use it in my system . I got 6 system using airlift and using one 60 watts air pump only .. and I never have any problems with it .

  11. I gave a thumbs down, I appreciate your time in the video, but you waste ours by dragging out the most simple statement, check both sides of the story, and you say it a few times, in a super drug out manner. I believe you should watch some videos and make a simple siphon, or airlift pump, and time the flow, and watch how high you can pump solids, which are aerated in the liquid. I built a few out of glass and was amazed how simple and effective they are, I built a simple air lift pump that lifts 18" off the top of the fish tank, no issues for over 3 months running 24/7. I measured the flow and it came out to 62.5ml/min. at 18" above fish tank water level. 10 gallon fish tank. there is no maintenance to them, other then wipe them off(maybe). What about electronic pumps, with filters that clog and over heat and can't pump solids? please take this as constructive criticism of this video and that people should not discredit these amazing airlift pumps. blessings

  12. Don't agree with your analyst. .on my view. .air pump is best ..either way..push water up & add more oxygen into water will never need water pump anymore. .save electric. .no maintenance. How high water up depend on the watts of airpumb..u can use it to small water pump & make it double water flow with oxygen. .

  13. I compare airlift pumps and bubble aeration with religion: no matter how much scientific proof, some people will continue to hang on to their belief.
    In this case that airlift pumps are in any way energy efficient (they are not),
    and that bubbles can aerate the water efficiently at the low submergences we encounter in aquaculture and aquaponics, they do not.

  14. Absolutely no air lift pumping for water. It will cost more capital, more energy, and more maintenance. Statements on better energy efficiency are totally wrong. No advantages at all compared to a water pump and a separate air pump. Use a water pump for pumping water. Use a low output pressure air pump (less than 5 PSIG rated) for the air like the ones used for ponds. The higher pressure air cost will cost a lot. An air lift system can not produce the same water pressure without a lot more cost. Use a piston air pump, not a diaphram pump type for excellent reliability and efficiency. Water submergence is 1 psig output required per 1.5 feet of water. This will give you some extra for pressure loss through the air diffuser.

    Use rubber membrane fine bubble diffuser because it allows more air volume and less pressure drop. They also do not plug as easily. There is no need to submerge the diffuser too much because the aeration process will agitate the water and create a circulation in the tank.

    Pipe sizing: 1 inch pipe for up to 20 GPM. 2 inch pipe for up to 80 GPM. 3 inch pipe for up to 180 GPM. In general, you want to keep water velocity at less than 10 feet per second for enomical energy and water erosion in metal piping systems. You can flow a bit faster in plastic pipes by the pump cost will begin to bite.

    My qualifications: 39 years in chemical plant, refinery, and wastewater treatment system design. Currently designing an aquaponic system for my backyard.

    Thanks for the excellent videos.

  15. Now if I had an above ground pool that is at least 3' depth on a platform, I'd put a syphon pipe in with an airstone down the center and air lift it out the top of the pool and down into the 55gal tanks swirl tanks and then let gravity move the water down levels of growbeds from 3' to groundlevel and ultimately into a below ground sump tank where I'd use a pump to recirculate back into the pond. In that style of CHOP system an airlift would be useful, but ultimately you'd still need a mechanical pump in order to complete the cycle.

  16. As for airlifts, I do a hybrid. I use a normal pump but I added an airstone to the water surrounding the pump so it will become aerated before getting pumped. This allows for a better GPH and the "effluent" to the grow beds is already aerated which helps plant growth and bacteria functions. But I agree, I tried the airlift and you need 4times the depth to the height of lift. So if you want a lift of 1ft above water, you need your input to be 4ft below the waterline. Airlifts are not good for shallow applications. I have a pond that I'm constructing that is 3' below ground and I am using 55 gal drums as the swirl/initial biofilters. They sit above ground and so I would never be able to lift the water to the top holes of the drums if I used an airlift unless I drastically reduced the diameter of the pipe going up from the pond. Smaller diameter means less flow and also the possibility of plugging the system (hence the high maintenance issue).

    Airlift pumps sounds good experimentally (not theoretically) but unless you are just using an airflow pump inside the tank just to create a circulation from a bottom substrate biofilter up pipes and out at the water surface, the whole concept is worthless.

  17. The first question, must make sure there is never a plug or failure in the system. I have a CHOP system on my aquarium where the 55 gal fish tank is the lowest and I use a syphon tube into a bin at the same level as the tank which has its own air bubbler and floating medium that works as the initial biofilter. The pump is in this basin and pumps the water up above the tank where it then drips into a series of pots filled with grow media and plants and then ultimately back into the fish tank. If the dang lizard that goes around searching for bugs disturbs a drip line water then leaks onto the floor and I come out the next day to a half filled tank. If the syphon hose plugs up the water overflows over the top of my aquarium. I made my system on the cheap and I didn't add safeguards. Unless one adds safeguards like overflow and move the pump up so it doesn't suck all the water, etc… the system will be high maintenance as a person will need to be closely monitoring for failures.

  18. AG,

    Not sharp shooting here just trying to make sure I am understanding correctly. I think you may have misspoke in the part of this video at about 6:40 mark when you talk about the HRT for the tank with the smallest fish which you want to recirculate every 2 hrs. You took the tank volume /2 /60 to get your flow rate. What I think you meant to say was Tank Volume x2 /60 to get the flow rate required to turn the tank over every 2 hours.

    If I am wrong my bad, just want to make sure I write this down correctly. I am going to start my small home system soon to cut my teeth on with the thoughts/dreams of going to a larger and maybe commercial system later on.

    The quality of your vids and the materials covered keeps improving. Great job.

  19. I like your approach on looking at different aspects. I would like to suggest that you check a youtube channel by Natalie Cash. She works with a man named Glenn Martinez, who may just change you mind on the use of Air Lift Pumps. He has really made some innovations with this pump.

    He has a pump that pushes water up I think over 18 feet, don't quote me on that, just watch the channel.

    And one other thing, thank you for your service.

    God Bless

  20. I've actually been looking into airlift pumps used with a baffle hood and bubble tube line in D-ended Raceways like they use in aquaculture.

    They are best used in zero head applications. And D-ended raceways need the flow and are self cleaning.

    I like the idea of being able to section off the tanks for different size fish.

    I've also been looking at Insulated concrete forms and Hydronic heating and cooling, multi aqua makes a nice solar 5 tone unit.

    Also been looking at fiberglassing tutorials for koi ponds.

    One of the advantages I think you left out of airlift pumps is the ability to pump Solids without clogging like a typical pump would.

  21. Thank you again and again for your awesome videos! I have one question concerning flow rates and plants; does flow rate affects nutrients uptake by plants? I am going to build a system kinda similar to this one where water is pumped from the sump tank to fish tank and from fish tank to filtration to grow beds by gravity.

  22. I can't say enough thank you for the great job you are doing man, your channel has openned up a new world to me. and the knowledge I have gained in your videos. WOOOOOOOO! is how I can sum it up. Thanks a lot for the gift man.


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