Thread: Airlifts - pumping water around a gravity system using only air

Hi Dave,I went for the " U " bend one far easier to do.
I did make a chamber for the air on the up flow pipe but as you say an air stone is good.
I then cut through the block wall for my return to just below water level,had to be carefull as pond is fiberglassd then fitted a screw on 4" tank connecter.
I only had room for 1 T piece for the air to escape but works fine.

I have about 2m of horizontal pipework (including a ball valve) between my air lift and my pond. Using 110mm/ 4" pipework.

You could probably have a fair bit more if needed, but always best to keep it as short as possible to reduce flow loss.

I think reducing the number of bends, and making them as gentle as possible, is the main thing to focus on for the pond return.

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One way you could do it is to have the u bend close to the pond where the water will return (although not too close, allow space for bends and valves if needed), rather than close to the filters.

That way, when you dig the pond out. Just dig out a chamber into the side of the hole big enough to accommodate the u bend. That's essentially what I did. I even laid a bit of a concrete base in the side hole, just to ensure the airlift has a stable base, as once full of water it'll be fairly heavy.

You could even run 2 x 4" pipes from the filters into the same u bend if you are worried about flow being restricted. Again that's what I did, although it's a bit over kill and not really necessary.

Personally I think you'll be fine with all 4" pipework and a single u bend airlift moving water 5m from filter to pond.

On mine it's about 1.5m between filter and air lift and 2m between air lift and pond return, albeit with 45° bends where possible. And I have to dial my air back to reduce the flow on the airlift.

I can't see that an extra 1.5m of horizontal pipework would be much of a hindrance.







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I know is this not the right thread and will possibly mess with your head but before you get to far to having a shower filter yes a lot of people have them but a lot of people have also got rid of them due to harbouring all the nasties and making it very hard and every expensive to get rid of parasites. . Am not saying showers are the devil but just some thing to think about .

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Originally Posted by Hesomable

That's perfect thankyou I don't know how to upload pics as I use the mobile version my pond has been a ballach to get up to ground level as iv had a lot of issues to contend with I have a freind who is a architect and another 2 that are skilled builders and all agree it's been a bit of a nightmare as we are on a corner house and it's at the top of the garden so digging out and building walls and footings and keeping them all meshed and locked together as we went along was a bit of a nightmare also didn't help that next door had built a shed on our vicrorian devididing wall with no footings so was very nervous digging up close building walls then concrete backfilling it . The downside is my pipe work for the 2 bottom drains is having to go in the corner of the pond internally I'm going to use valves like ukzero has on standpipes the plugs side now however is we're at floor hight so can now get the runs in for the pipes I'm planning on sending 15000 to the bakki shower off the 20k vario and then having 10000l off a airlift back to the pond the only trouble is I need to work out where to rut the 4 inch return hight wise some I see saying 5cm below waterline othere I have seen say at the waterline

What hight is everyone using airlift set at would you say

Hope this makes sense

The top of my pond return is about 15cm below the water level in the pond.

Personally I'd say aim to have the top of the pond return somewhere close to the expected water level or just below it. It doesn't need to be exact.

You can have the pond return sat just above the water level. But I wouldn't say this is ideal if building from scratch.

I say this because, the constant movement of water will make it harder to see the fish. It'll create a constant splashing sound (which may not be a bad thing if that's what you want). The pipe will be visible, so could ruin a natural look pond or if you want it looking neat. Also, you will lose a bit of flow just because you are trying to lift the water above the natural water level.

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Originally Posted by Hesomable

That's perfect thankyou I don't know how to upload pics as I use the mobile version my pond has been a ballach to get up to ground level as iv had a lot of issues to contend with I have a freind who is a architect and another 2 that are skilled builders and all agree it's been a bit of a nightmare as we are on a corner house and it's at the top of the garden so digging out and building walls and footings and keeping them all meshed and locked together as we went along was a bit of a nightmare also didn't help that next door had built a shed on our vicrorian devididing wall with no footings so was very nervous digging up close building walls then concrete backfilling it . The downside is my pipe work for the 2 bottom drains is having to go in the corner of the pond internally I'm going to use valves like ukzero has on standpipes the plugs side now however is we're at floor hight so can now get the runs in for the pipes I'm planning on sending 15000 to the bakki shower off the 20k vario and then having 10000l off a airlift back to the pond the only trouble is I need to work out where to rut the 4 inch return hight wise some I see saying 5cm below waterline othere I have seen say at the waterline

What hight is everyone using airlift set at would you say

Hope this makes sense

Rather than have the BD pipes come up inside the pond, why don't you just box them off with breeze blocks, so they sit outside of the pond?

I doubt you'd lose much pond volume if you did that. And if its all in pressure pipe, once you test them for leaks you hopefully won't ever need to be able to access them again.

One thing I would suggest is to t off from your BD pipes and have purge lines on them both. That is the number 1 way to remove all the muck that settles out in the bottom drain pipes.

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Originally Posted by noo

This thread has inspired me to try airlifts too.

I want to use 110mm pipe with 2 meters length/height but I need to raise 100mm over the water line to get over the pond wall. I'd like to achieve 30,000 - 40,000 LPH in total perhaps with 2 or 3 airlifts each receiving 60 LPM of air. Possibly directly from a drum filter (drum has 3 x 110mm outlets, designed for 55,000 LPH flow) or perhaps airlifts from a 5000 litre holding tank directly after the drum filter.

NickK-UK, would you be kind enough to calculate the flow rate difference if I used an internal air chamber (90mm pipe) inside the 110mm pipe? It's really difficult to step up to 160mm chamber due to the lack of fittings where I live.

If the flow reduction is significant, I will try to import 160mm fittings and copy what everyone else is doing.

Thanks in advance

Hi I've just seen this request - sorry I didn't see this before!

Probably worth drawing it so I can see what you're describing.


It sounds like you want the incoming water to go down the 90mm in the centre of the 110mm pipe then pulled up via the 110mm?

Originally Posted by noo

Hello Nick, thanks for chiming in.
I wanted to copy the 5 or 6 inch external air compression chamber on 110mm uplifts like everyone else but it's not easy to source those parts where I am. See A of my diagram

I am able to step down from 110mm to 90mm fittings easily with an internal air compression chamber but that would create a restriction of the 110mm pipe diameter with a reduced flow. See B of my diagram. What I was trying to determine is how much of a reduced flow.... ? The reduced cost, ease of parts and time saving may be worthwhile as I could add another airlift to make up the difference.

However, I have settled on option C of my diagram using a 110mm TEE and putting the air diffuser below and out of the water path. So I can keep the 110mm pipe diameter and reduce costs and not have to import bits from across the world.


AIRLIFT DIAGRAM.jpg

On those diagrams - all would work but the right most (opt C) may get some bubbles travelling along the inlet pipe if there's any flow stoppage or during starting. Normally that would clear out with the flow but in the case of uneven piping that could result in an airlock preventing the flow starting.

The option B would essentially have a 90mm pipe and it's a bit of a pain to make. If I couldn't do A then I'd probably look at C too. It's a simpler design and that means easier maintenance.

Originally Posted by DiabloDave

Interesting post about the 6” fittings as I have looked online here in the uk and can’t find anyone who does any of them - which has made me start thinking about just going for a ‘U’ bend solution with a simple air stone (glued into the air hose so I don’t have to retrieve it should it come off) in the long rising pipe.

regarding air pump - on my trial I’ve got a 5ft long 4” pipe in the pond with an air stone in it - if tapped off my 60lph air pump that feeds my moving bed and it’s moving a lot of water. I trialled a 100lph air pump just on the air lift and it was far too violent that it actually negatively impacted the flow. I think the 100lph on two air lifts and the fluid bed will be perfect - that’s 80watts total and I think il be getting somewhere between 30-40k litres per hour on the water circulation. My concern is that having just these returns will negatively impact the pond circulation.

Plastic pipe shop have 160mm offcuts. I ordered two and used those with 160-110mm soft boots which works for me because they sit in a water chamber.

In option C would it not be better to have the air coming in where you have the water, and the water rising where you have the air.

Easy enough to do.