Gravity fed drip irrigation for tomato plants

I'm trying to set up a home-brew drip feed irrigation kit for 6 tomato plants. I've already got a lot of suitable tubing, the T-pieces, connectors, drippers etc. The water feed is off a new 230 litre water butt to which I have attached a brass tap instead of the black plastic one. To the tap I've connected a Hozelock electronic water timer (AC1), which Hozelock customer services confirmed will work with a water butt, and it does.
So I placed the tomato plant pots close to each other and close also to the water butt, then ran the tubing from one to the next. I then switched the AC1 to "always on" for testing.
The problem is that even when the butt is brimful it seems to have only enough head of water to feed three of the drippers. And even then the third dripper furthest away from the butt dribbles rather than drips. The water will just not flow around the circuit to all 6 drippers, and I can't understand why not! I even tried sucking on the little pieces of tube as if to "bleed" them of air. No improvement.
The feed to the first 2 pots is excellent and the water drips really nicely. So it would work for 2 plants, possibly 3. But where am I going wrong? The water butt is mounted on the typical black plastic stand, which is about a foot off the ground.
MM
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wrote:

First thing that comes to mind is those aquerium valves, that clip together to form a manifold.
--

Graham.

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The pipe from the timer should be acting as a plenum chamber, and water should reach all six drippers at the same pressure, and they should all drip at the same rate. If the water won't flow to all six drippers, there has to be a restriction or blockage somewhere, either at the input end, for example the outlet from the butt or the AC1 timer, or a blockage in the pipe before the last three drippers or in the nozzles of those drippers themselves. AIUI the holes in the drippers are small and easily blocked by debris. Check that they're clear. There could also be a bit of crud stuck in one of the connectors, possibly between drippers two and three. Is there a filter in the system somewhere that might be doing its job so well that it's become blocked?
Do you get a good flow from the brass tap on the butt when you open it, with nothing connected? Water should pour out. If it does, then the tap isn't restricted or blocked. Attach the tubing running to the water timer and set the timer to 'always on', but don't have any tubing connected to the down-side. Water should pour out of the outlet from the timer. If it does, the timer itself isn't causing the restriction. Then connect the first dripper. Does water reach it so that it drips OK. If yes, connect the second dripper, and so on until you reach the point when an additional dripper doesn't drip. The blockage will be in that section of pipe.
If there really isn't a blockage anywhere in the pipework or drippers, another suggestion would be to make the feed pipe into a ring system. Put a T-piece into the pipe just downstream of the timer, and connect the blind end of the existing chain of drippers back into that T so that you have something like a domestic electricity ring main. That will allow the drippers to be fed from two directions, so if one leg becomes restricted, the other leg will continue to supply the drippers on the other side of the restriction.
--

Chris

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No, I checked every piece of pipe, every connector, every dripper. There is no restriction anywhere.

No, I've blown through all the pipes and eyeballed the connectors or blew through them into a glass of water to check for bubbles.

Checked. It does pour out. It also pours out on the outlet side of the timer when switched on. The flow from the first piece of tubing is good, but not forceful as it's only 4mm approx diameter.

It reaches three drippers, but not the fourth. The first two flow strongly, the third not so much. The fourth barely even drips. I've tried a ring formation and an inline formation. No difference.

I think the basic problem is not enough pressure. This PDF file from Irrigation Direct has a lot of information about gravity feed watering systems. It points out that to obtain a reasonable head of water (15 psi), the water butt would need to be 34.6 feet off the ground. http://www.irrigationdirect.com/media/manuals/owners-manuals/irrigation-direct/Drip-Irrigation-Kit-Instruction-Manual-Gravity-Feed-Kit-for-Vegetable-Garden-GFVG.pdf
or http://preview.tinyurl.com/z6lxpsr
MM
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I still don't see what's limiting the flow. Logic says that something must be. Or is the total flow rate that you want, too much for the bore of the tubing you're using and the head available? Wider bore tubing needed?
--

Chris

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Yes, that last one I had thought of, too. Maybe I'll get some on Monday and try.
MM
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MM wrote:

My drippers are designed to be fed with one bar pressure and even then take several minutes to propagate to the end of the line when first used at the beginning of the season. Could you stand the pots on a gravel bed in a water fed tray?
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On Sat, 7 May 2016 17:25:57 +0100, Bob Minchin

Ah, you mean, feed the outlet from the timer to the tray so that the tray always fills up/is topped up, the rely on capilliary action for the water to enter the pots from below?
I like it! Trouble is, I don't have a tray... Maybe I could use a storage crate and make a tray out of that by cutting the sides down. Mind you, cutting that type of plastic ain't fun!
But yes, it's a good idea, and I do have the gravel. How would you arrange the pots? Put the gravel in the tray, then stand the pots on top, or put the pots in first and add the gravel. Actually, what purpose does the gravel serve? I assume that the water level must be some way up the side of the pots, say an inch minimum?
MM
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On Saturday, 7 May 2016 17:42:38 UTC+1, MM wrote:



If you want to water them by capillary action, the water level must be belo w the bottom of the pot, not above. The pots must stand on some capillary m at, which delivers the water. I used this system long ago. I've also tried doing this with polythene pots using cardboard as the capillary mat, and it works fine. Gravel can be added after the pots are placed to reduce evapor ation.
NT
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On 07/05/2016 17:25, Bob Minchin wrote:

On a timed system air will enter the system every day and more so on a hot day. The drippers are just open to the atmosphere and on a very hot day, and with black pipes, the water in the pipes will expand and be pushed out of the drippers. The water is not replaced unless the water meter is on.
The op is using a water butt with a head equivalent to approx 0.2 bar.
To the OP, when the manufacturer stated that the meter works with a water butt did they specify the diameter of the tube/hose it would be connected to. It may work extremely well with a large diameter leaky pipe etc.
Water takes the path of least resistance so possibly the first 3 drippers are open too much and the system needs balancing by throttling back these drippers.
Try connecting a single piece of tube without drippers to the water meter. Collect all the water it produces over a short timed period. Now connect the tube with the drippers and place all the drippers in a bucket and collect all the water now produced for the same time period. Do the two amounts match - if so this is the total that the system can supply so you may have to have each dripper supplying less water for a longer period.
--
mailto: news admac {dot] myzen co uk

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On 07/05/2016 15:32, MM wrote:

Try using several T pieces to set up a pseudo-radial network of tubing feeding individual or pairs of drippers. This way each pair/single will be fed down identical lengths of pipes with hopefully equal resistance. Also suggest following previous advice to use a ring setup if feeding pairs of drippers.
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On Saturday, 7 May 2016 20:04:36 UTC+1, Robert wrote:

That's exactly the solution. A likely alternative is to make a ring circuit to feed the drippers.
NT
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Are these drippers 'designed' to be run at mains pressure? If so it may simply be that the ones nearest the butt are working at all? Are they adjustable?

And presumably the drippers are in the tops of the pots and so also off the ground by some amount, so you are (just) relying on the head of water in the butt to provide the 'pressure', rather than the height of the butt above the ground?
How about taking the drippers off and setting the timer to run for a shorter period? I see no reason with that setup why the water shouldn't make it to the last port, but only if there isn't a large amount of back pressure required to overcome some of the drippers?
I know when I kept tropical fish is was difficult to balance any air-bricks or air powered filters if the air hose was in a single line (Tee'd from the same bore hose). So I made up a plenum chamber from a tin can with some brass tubes soldered in and that made things much easier. It was interesting to see this can 'inflate' slightly as the pump brought the system up to pressure (I had one of those induction motor piston pumps and the plenum also ironed out the pump 'strokes').
Assuming all your drippers are supposed to be the same, it would be interesting to see how they compared when they were all fed in parallel, rather than series?
Even when running mains pressure feeds to my runner bean plants (also via a Hoselock timer) it was interesting to see the wide range of 'jets' you saw across all the outlets, even when being fed from a common larger bore hose.
Cheers, T i m
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Probably. The info leaflet doesn't say. It was a very cheap £3.99 kit from QD a couple of years ago.

Not adjustable.

Correct. But the height of the butt above the drippers is approximately 1m.

The Hozelock doesn't give many options:
PROGRAM DESCRIPTION 2 mins Valve opens for 2 minutes, every 24 hours 5 mins Valve opens for 5 minutes, every 24 hours 15 mins Valve opens for 15 minutes, every 24 hours 30 mins Valve opens for 30 minutes, every 24 hours 60 mins Valve opens for 60 minutes, every 24 hours P1 Valve opens for 2 minutes, every 6 hours P2 Valve opens for 2 minutes, every 12 hours P3 Valve opens for 10 minutes, every 12 hours P4 Valve opens for 15 minutes, every 2 days P5 Valve opens for 60 minutes, every 2 days P6 Valve opens for 30 minutes, every 3 days P7 Valve opens for 60 minutes, every 3 days P8 Valve opens for 120 minutes, every 7 days
(copied from the instruction leaflet)
I've got mine set to P1 at the moment for the three drippers that do work. As I said elsewhere, I'm taking the remaining three pots to my brother's while I'm away.

Having read up on the whole issue of gravity irrigation in the past couple of days, it's becoming pretty apparent that the problem is lack of water pressure. One might assume that 230 litres of water would provide plenty of pressure, but it's actually minimal.

Yep. These are all things I'm going to look into after the hols!

Ditto.

Yeah, but you got jets! Prior to the drip feed gubbins I used my own watering pipe design, consisting of about a 2 metre length of 15mm copper tubing (as used for plumbing) and a hose connector on the end. I squashed the other end of the copper pipe flat so that it didn't leak. Then I drilled small holes along the pipe. Connected to the mains I, too, got amazing jets! All different directions. It functioned as a rudimentary lawn sprinkler and I've had it for at least 15 years.
So then the tomatoes and holiday. What to do? So that year (last year) I had planted out the tomatoes in large plastic storage bins, three plants per bin, effectively giant "grow bags". It was easy to pull them together in a line so that I could lay my copper watering pipe across them all. Bingo! A lot of water sprayed on to the lawn, sure, but a heck of a lot got to the plants. The perfect solution. A Hozelock water timer was bought and I sat in the garden, in testing mode, waiting agog for the timer to switch on for its 2 minutes every 6 hours. It did and I was so pleased I went and made a cup of tea.
Then I had nightmares the whole holiday when I was away as to what could happen if the Hozlock timer "froze" with the valve OPEN due to a battery or internal circuit problem*. I was imagining water bills in excess of £1,000. So I said, never again. Hence the water butt and this latest experiment. If it's a total failure and I return to find the tomato plants all dead, it's not too late to sow fresh seeds. Well, actually, three won't be dead, because my brother had better water them (see above)!
* Hozelock caution against using rechargeable batteries. Apparently, the discharge rate of rechargeables is unpredictable, compared to non-rechargeables, which ARE predictable. So, what the timer does, before opening the valve when a watering event is due, is test the batteries for enough power to close it again, and if there isn't enough, it won't open it. When rechargeable batteries are used, however, the timer may "think" there's enough juice left, but there isn't. So the valve opens... and then will not close. Result: Permanently open until one returns to find water, water everywhere! One might be lucky if the neighbours noticed excess water and switched the water off at the meter in the pavement, but they might be on holiday, too.
Of course, I've NEVER used rechargeables for the water timer!
MM
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<snip> >>Are these drippers 'designed' to be run at mains pressure?

Ok.

Ok.

Oh, that's gotta help.

Ok, if you weren't and depending on the free flow of the hoses (minus the drippers) used and the size of the pots, if you set it to some value that was able to deliver enough water to sufficiently water each pot, and the pots were also sitting in sealed trays (to catch any over watering), mightn't that do it?

Quite (been there found that out etc) so what you want is a controlled 'flow' (fairly independent of back pressure) over sufficient time as to ensure all the plants had sufficient water each day, just as if you walked along with a watering can? All you would need to do to test that is to pull off all 6 drippers, turn on the timer and see how long it took for the worst case to have been given sufficient water. If it takes 5 mins then you could set it to P2 (2 / 2m / day)?

You may not need to if my suggestion above works? I think the thing here is as you say / read up on is that you are running what could be high pressure drippers off a low pressure system. So, you either provide that pressure (automatic pump (only comes on when the outlet is drawing water via the timer) in the butt with a low level cutoff) or change to a system that uses flow.

You could only hear them as they were under that black weed-control fabric. ;-)

So that was the plenum type design, cool. ;-)

Hehe.

Yup, can be a risk if on a metered supply.

I was going to say 'yes, no lives have been lost' but I guess that depends on how 'green' you are. ;-)

;-)

That's clever. Funnily I just took a Hoselock timer to bits (I believe it was split in the frost but it might not have been) and it was interesting to see how it worked (mechanically).

;-(

Or wonder why their hose was flooded? ;-)

I think that because there is such a difference in voltage between an alkaline and typical rechargeable equiv (NiCad or NiMh etc), the good systems allow you to select which is installed and the 'Low battery' warning (or process, as in the Hoselock AC1) would be able to work more accurately. My Garmin GPS III+ and V were such devices and you would tell it which type of cell was fitted and it would warn / shut down at different voltages.
I am interested in your experiments as Mum has a couple of large water butts and a load of pot plants she would like watered when away for a few days (rather than just relying on us).
She has a pump in one so we can use a hose when there but something automatic and reliable would be better. I had considered using the pump to automatically feed a header tank mounted up higher and something like an Arduino and float switches to manage the levels but I think there are low voltage pumped - solar systems out there already that do similar.
Cheers, T i m
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[snipped for brevity where appropriate]

Agreed. My basic problem is that I *assumed* it would all just work! I should have started planning the system weeks ago. Too late now, because my British Airways plane is already on the tarmac, so to speak. But all your tips will be looked into when I get back.

I, too, thought of an inline pump (e.g. Whale Standard 12V Submersible Electric Pump) somehow wired into the Hozelock so that when the Hozelock opens the valve the pump comes on. That would surely provide enough pressure to feed twenty pots.

It worked/works very well when I was living very frugally while waiting for the pensions to kick in and couldn't justify a sprinkler, which I now have treated myself to a couple of years ago (from Wilko).

Ah, yes! Good point. Where I used to live in Bucks we had no meters! It wouldn't have mattered (well, my conscience would have pricked a bit).

How weird! No, not that you took it to bits, but that *I* had EXACTLY the same thought myself over the past day or two, especially when I started considering that inline pump and what would be involved in hooking up a Raspberry pi or Basic Stamp to the circuitry. However, I haven't dismantled mine yet, as it wasn't cheap. What is actually inside these timers?

I love technology!

Okay, well, wtatch this space, because as soon as I've worked out a viable *long-term* solution, I'll document it. Probably re-inventing the wheel, but there ya go. It's all rather too daft for some people, who say you can buy tomatoes at Tesco or Asda any day of the week, why Bother? But you have to try these things! (I tell 'em.)

Ditto
MM
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<snips> >>That's clever. Funnily I just took a Hoselock timer to bits (I believe

Quite, and it didn't seem like it was designed to be taken apart.

Well, in mine there was a fairly traditional (and well greased) nylon ball-valve with a little gear train driving it from a fairly small motor and an end-stop switch. Also a neat PCB. ;-)
https://dl.dropboxusercontent.com/u/5772409/Water%20timer.jpg

<snip> >>I am interested in your experiments as Mum has a couple of large water

Cool.

Hey, you never know when you come up with a new / alternative design. ;-)

Well, I did have a go and growing my own for a couple of years and can say that whilst I had some success (runners and onions mainly) the rest was more time, effort and faff than was worth the cost saving or taste improvement for me. [1]

Unfortunately I'm not a fan of veg as such (but eat quite a bit because I 'should') and whilst I can sometimes taste the difference between 'home grown' toms and 'forced' mass produced stuff, it's not enough (for me) to justify the extra effort.
I think the biggest example of a 'complete waste of time' was trying to grow 4 Brussel sprout plants. Constantly trying to stop creatures eating them before I could and then I ended up with 4 stalks with marble sized sprouts on them and I could buy fully formed versions for £1 / stick in Sainsbury's. ;-(
Cheers, T i m
[1] I think I'm what they call a 'Supertaster' and believe the nasty side taste I get from most brassicas is the same as I get with most sweetness etc. I now have no sugar in tea of coffee (after have two teaspoons most of my life) and went 'cold turkey' rather than put up with sweeteners. Mrs has sweeteners and has no issues with them?
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[snip]
Stop Press!!!
The heating engineer was here today to service the boiler. He's the same chap who replaced my leaky single-skin oil tank with a bunded one last October. So we got talking and I pointed to the water butt and pipes. First thing he said was, the 4mm pipe is offering too much friction for the very small volume of water flowing through it. His suggestion was: Get a piece of standard 13mm garden hose, put a bog-standard push/click connector on one end and connect it to the Hozelock. Then drill very small holes along the hose in the right places. Oh, and block off the end of the hose after the last plant.
I did it and it works perfectly! I had to have two goes, though. The first time I drilled the holes with a 3mm drill, but the water consumption would have been quite high over two weeks, so I did it again, this time with a 1mm drill. All six plants are getting a nice watering for 2 minutes every 6 hours. I topped up the water butt to the brim and that's going to be it for now. The hose sits nicely across the top of the pots, but I stuck short lengths of bamboo cane down the side of the hose at each pot, just to ensure the hose stays in place. That is, imagine a tuning fork placed over the hose pipe and then stuck into the compost. I formed "tuning forks" out of two pieces of cane.
MM
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<snip> >Stop Press!!!

Hmmm, I could imagine that the case if you were looking for a good flow as that requires 'volume' but for a dripper role? I bet if you had just left one open ended 4mm pipe on the floor with the time on 'On' it would empty the butt before you thought. Even a small leak will spread water all over the place pretty quickly.

So more like a 'leaky hose' solution or the std Hoselock 'distribution' size hose for a std water distribution system (that you pierce and fit the thinner hose that go to each pot).

Which sounds very close to the idea of P2 and just taking the drippers off your initial system. ;-)

As long as you ended up with something that works, that's the main thing.
Now relax and enjoy yer hols. ;-)
Cheers, T i m
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Follow-up after holiday:
I returned on Friday. The tomato watering system obviously worked, and was still working. Unfortunately, the tomato plants don't look too brilliant. They have brown flecks on some of the leaves. Too much watering? Apparently, it has been very wet in South Lincs.
Anyway, the principle worked!
MM
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