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  1. #1
    Senior Member Rank = Yonsai Dudley's Avatar
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    What size air pump.

    Hi.
    I am sure this question has been asked before but I cannot see any threads for it.

    Pond is bowl shaped at 1500 deep by a varying 5-6m diameter. I have calculated surface area to be around 10-12m2. Water volume 30,000L

    Going by Manky web site 60L of air per min does a surface area of 5m2. So I should be looking at 120Lp/m, but I do not want to overdo it as my fish stocking will be very low and I have other moving water from 2 waterfalls, also want to see in the water and not be looking squinting through a boiling cauldron.

    Also what type of air pump, bearing in mind in the summer I will have it at 1.5m down. Really looking at 2nd hand for now to keep cost down. Have found a used SECOH EL-60 on eBay for £90. But I know newer pumps are more economical. I will run it in the winter so energy consumption is worth thinking about.

    Thanks in advance
    Steve



  2. #2
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    I think you will find when it comes to getting the correct sized air pump you need to consider the length of run and restrictions in the pipework. You also need to consider how much air is required for the surface area of the pond without turning it into a jacuzzi. It's like anything you are trying to push through a pipe or a tube etc the longer the run, the more bends, the more changes in height and other restrictions the less you can push through it at any given flow rate. Or to gain that flow rate you need more pressure. Like water pumps it's always better to go a bit bigger than you need as you can always turn them down a bit if they have a speed controller or in the case of an air pump fit a manifold and vent off what you don't use. Just need to fit flow restrictors to regulate the amount of air you pump to each place and it's a good idea to fit an air stone on anything you vent to atmosphere that you don't need or it will make a very annoying sound with air pumping out under pressure all the time.

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  4. #3
    Senior Member Rank = Yonsai Dudley's Avatar
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    Quote Originally Posted by Frimley Koi keeper View Post
    I think you will find when it comes to getting the correct sized air pump you need to consider the length of run and restrictions in the pipework. You also need to consider how much air is required for the surface area of the pond without turning it into a jacuzzi. It's like anything you are trying to push through a pipe or a tube etc the longer the run, the more bends, the more changes in height and other restrictions the less you can push through it at any given flow rate. Or to gain that flow rate you need more pressure. Like water pumps it's always better to go a bit bigger than you need as you can always turn them down a bit if they have a speed controller or in the case of an air pump fit a manifold and vent off what you don't use. Just need to fit flow restrictors to regulate the amount of air you pump to each place and it's a good idea to fit an air stone on anything you vent to atmosphere that you don't need or it will make a very annoying sound with air pumping out under pressure all the time.
    Thanks Frim

    I just erected a summer house with a deck projecting over the water, mainly for hiding filters beside it and to have somewhere for connecting the electrics. But don't tell the wife, she thinks I put the summer house up for her
    But it means air pump will be really close to the water with little to no bends in the line. Estimate 8m maximum run of pipe.
    I may go with this SECOH EL-60. Googled it a bit and it looks to be a reasonable pump.

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  6. #4
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    Quote Originally Posted by Dudley View Post
    Thanks Frim

    I just erected a summer house with a deck projecting over the water, mainly for hiding filters beside it and to have somewhere for connecting the electrics. But don't tell the wife, she thinks I put the summer house up for her
    But it means air pump will be really close to the water with little to no bends in the line. Estimate 8m maximum run of pipe.
    I may go with this SECOH EL-60. Googled it a bit and it looks to be a reasonable pump.
    Don't tell the wife LOL your secrete's safe here as long as she never comes on this forum LOL

    SECOH are good pumps I think and if I remember rightly I have got one that will be fitted on my QT.

    When I was looking for air pumps I noticed that some of the descriptions said that the pump was good for depths of down to 1m or 1.5m so may have something to do with the water pressure on the air stones or diffusers below certain depths. The bigger the pump the deeper it could handle I think. I could be wrong on this but if I find the site I'll put a link to it.

    With the air stone and disc in my pond I just stuck air lines on them, attached them to the air pump and went for it but as my pond is much smaller than yours I didn't have the same length or bends etc. Well I started off with just the big 200mm diffuser in the pond and the smaller air stone somewhere else just venting to atmosphere and then dropped that into the pond as well when the temperature picked up last year and it has been in there ever since. I can't remember what make of air pump I have running them but I am fairly sure it's a 60 lpm one. The air lines are 10mm silicon hoses held on with jubilee clips.

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    Not sure if this will give you the exact page but if not look at the air tech ones and you will see what I mean about maximum working depths

    Coastal Koi - Airtec - Secure Online Shopping

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  10. #6
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    The air pump on my main pond is an Aqua Eco Hi Blo 65. It is not very noisy and quite economical to run at 40 Watts. It comes with a T fitting with 2 valves on, a rubber elbow and 2 spring type clips to hold the elbow onto the pump and T fitting

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  12. #7
    Senior Member Rank = Yonsai Dudley's Avatar
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    Quote Originally Posted by Frimley Koi keeper View Post
    SECOH are good pumps I think and if I remember rightly I have got one that will be fitted on my QT.
    I think you made a typo above Frim. You say “will be fitted” don’t you mean “is fitted”😉
    Sorry I had to get that one in. 😃

    The guy selling the air pump says,
    other brands of air pump quote the ‘open flow’ rate, which doesn’t account for back pressure from piping and operation depth and the associated reduction in blowing capacity. This means that a ‘60lpm’ pump may only achieve 40lpm at the depth you’re likely to run at. Conversely, Secoh pumps don’t quote the open flow in their model numbers, but rather the pump rate at 0.2 bar optimal pressure. They are therefore more powerful than you may expect. A 60lpm Secoh pump will blow 105lpm of air ‘open flow’!

    So if he is correct they sound a good pump. This uses a tad more power at 60w
    But from your links it looks like I can get a new 60lp/h for the same money as this SECOH. It’s going to be one of those, do I buy new or chance used. If I go with used I could end up buying a service kit, although he says only been used for 5 months since diaphragms replaced.
    He only lives 3 miles from me coincidently.
    Thanks again
    Steve

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  14. #8
    Senior Member Rank = Yonsai Dudley's Avatar
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    This makes me think of my other hobby, scuba.
    I use air for that too obv, but not just as breathing gas, We have been trying to uncover a WW11 bomber in the mud off Herne Bay. We take spare 15L cylinders with 232 bar of air down with us and attach a converted regulator hose to a 4” diameter flexible pipe, open the valve slightly and let sone air flow up the pipe. Push the pipe into the mud, open up the air a tad more and hang on for your life. The air shoots up the pipe as it goes to surface it expands and accelerates. This causes a vacuum and drags up with it the mud.
    Works really well.
    Only problem is, when we surface and the next tide comes in it covers up everything we have exposed and can’t quite move forward.
    But it’s interesting to see how affective bubbles are at moving shit and circulating water, powerful stuff air when it’s under water.
    Unfortunately I missed all scuba last year due to a little heart attack. I hope to be back at it very soon though.
    Off to be fitted for a dry suit tomorrow that I ordered and paid for a year ago, put a stop on it as it was just days before my heart problem.
    Last edited by Dudley; 23-04-2019 at 11:50 PM.

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    Lol it's no typo Steve, it's will be fitted. You obviously haven't seen my QT thread lol. My SECOH air pump is still in its box in the garage. The guy I bought it off said it is more powerful than you expect so would back up what you said above.

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  17. #10
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    Sorry to hear about your heart problem Steve.

    I know what you mean about air and water as I made an airlift last year just to see if I could get it to work and had a bit of a play around with it to see how alterations effected it. Very simple and effective way to move water compared to a standard pump.

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  19. #11
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    Just checked my air pump and it is a SECOH JDK 40

  20. #12
    Senior Member Rank = Yonsai Dudley's Avatar
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    What size air pump.

    Quote Originally Posted by Frimley Koi keeper View Post
    Just checked my air pump and it is a SECOH JDK 40
    I like SECOH web site. They show a performance graph of each pump.
    And they rate the pumps at being used at 200mbar, and not just free air flow out the water which was just as I was told.
    So your SECOH 40 will push 40lts at its operating depth.
    Shame they use mbar as the measure and not depth in water though as that can be misread.
    They use 200mbar as operating depth, and from my scuba training I know that 200mbar is only 1m below surface not 2m as one may think as 100mbar is air pressure at ground level, and we add 100mbar for every meter we go down.
    But it helped me to work out I really do need an 80 pump as mine will be at 1.5m down that will only give me 50Lp/m.


    Sent from my iPhone using Tapatalk

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  22. #13
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    Quote Originally Posted by Dudley View Post
    I like SECOH web site. They show a performance graph of each pump.
    And they rate the pumps at being used at 200mbar, and not just free air flow out the water which was just as I was told.
    So your SECOH 40 will push 40lts at its operating depth.
    Shame they use mbar as the measure and not depth in water though as that can be misread.
    They use 200mbar as operating depth, and from my scuba training I know that 200mbar is only 1m below surface not 2m as one may think as 100mbar is air pressure at ground level, and we add 100mbar for every meter we go down.
    But it helped me to work out I really do need an 80 pump as mine will be at 1.5m down that will only give me 50Lp/m.


    Sent from my iPhone using Tapatalk
    Thanks for the information Steve. Very useful to know about pressures converting to meters below the surface

 

 

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