Venturi Siphons and drip irrigation

andyinnycMarch 31, 2014

I am looking to use a fertilizer injector for use with both drip irrigation and with a drip hose.

I have tremendous pressure coming out of my hose bib - this can be muted with a pressure reducer.

My system will work off a timer.

I'm reading both yes/no reviews on the various brass 1:16 or plastic 1:20 venture siphons.

So, anyone with experience using these with drip irrigation?


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nil13(z21 L.A., CA (Mt. Washington))

I'm guessing you are talking about a hose end injector like a Hozon. They require no head pressure. In fact, I have had problems getting them to work when they are attached to the hose bib and then a long 50ft hose. I figured that way I didn't have to drag the bucket around. The static pressure from the long run of hose caused the venturi to not siphon. I had to put the venturi right at the end of the hose before the wand.

I now use a Dosatron which is just awesome and works with anything. It is just pricey. I think if you want a siphon injector that works with drip, you have to get one with a tank that is rated for low flow rates like 8 gph.

    Bookmark   April 2, 2014 at 11:34AM
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nil13 - could you point me towards your "one with a tank that is rated for low flow rates like 8 gph."

Google seems to not be my friend here.


    Bookmark   April 2, 2014 at 10:21PM
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nil13(z21 L.A., CA (Mt. Washington))

something like this?

Disclaimer: never used one like this

Here is a link that might be useful: fert injector.

    Bookmark   April 3, 2014 at 10:44AM
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I actually have an EZ-Flo. My problem is that it pulls fertilizer from the tank and pushes water into the tank (at the end of a 'cycle', the once full of fertilizer tank is full of just water).

So the fertilizer distribution is non-predictable/non-uniform.

A Hozon (yes, that is what I was looking at) doesn't empty fertilizer/fill tank with water. It just pull the fertilizer.

Is there a cheap(ish) alternative out there? I'd like to use drip emitters and a drip hose, but I'd like a predictable distribution. Or at least know when I'm out of fertilizer .

For my garden, the 300+ price of the Dosatron, et. al. is way out of the ballpark.


    Bookmark   April 3, 2014 at 6:07PM
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nil13(z21 L.A., CA (Mt. Washington))

If you want predictable and uniform you have to spend the money for a Dosatron.

    Bookmark   April 4, 2014 at 10:28AM
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Thanks for the response.

The Dosatron is outside my budget; I'll now have to settle for 'less than perfect'. This, as long as it works, is still acceptable given my hobby strawberry towers and beds.

dBay has a number of Venturi tube units which 'claim' to be good for drip and soaker hoses.;_from=R40&_trksid=p2045573.m570.l1313.TR2.TRC1.A0.H0.Xfertilizer+injector&_nkw=fertilizer+injector&_sacat=0

Specifically, these come in 3 sizes: 1/2 inch, 3/4 inch and 1 inch. Anyone know what the difference is in operation/water pressure requirements of the 3 sizes?

I'm assuming that the smallest size requires the lowest flow rate, but I can't find sufficient information.

I'm assuming my soaker hose is .4 gallons per hour per foot. 2 hoses x 50 ft x .4 gph / 60 = only .6 gallons per minute. I'm (obviously) concerned that this may be too low to trigger the siphon effect.

Less concerned about the towers - I can remove my emitters and just have the drip line spray directly down.



Here is a link that might be useful: eBay injectors (all shipped from China it seems)

    Bookmark   April 4, 2014 at 11:24AM
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I ordered two injectors from ebay in February. It took over a month for the package to arrive, and it only included one injector, even though two siphon hoses were in the package.

Last week I ordered two Mazzei injectors. Arrived three days later.

As I understand it, the difference in the sizes is all about the required flow. I don't think you could consider anything other than the smallest with the setup you are thinking of. I would suggest you peruse the Mazzei website for data on flows and ability to siphon. There are minimum flows and pressure drops necessary for even the low flow 283. Those flow/pressure data sets are all laid out for the Mazzei product.

Perhaps you could consider adding more soaker hoses (eg doubling up the length within the same area) and reducing the amount of time you run it on each cycle. Or drop the soaker hose and use drip line with higher flow emitters. That might bring you up to the minimum flows necessary for the smallest injectors.

I haven't hooked up the injectors yet, will be about two months before I do as I need to install the valves and timer I plan to use them with. So I can't comment about actual functioning and setup other than what I have read. Again, the Mazzei website has been quite useful.

    Bookmark   April 4, 2014 at 11:47AM
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Well, I pulled the trigger on eBay and purchased 2 1/2" and 1 3/4" units to play with.

Only one of the units has the hose, and the rest are bare.

Anyone know what size/part number at Home Depot the stock tube size is on these?

When they eventually get here (end of April) I will hopefully find that at least one size works as advertised.

Charina, while I registered at Mazzei, I was still unable to use their tools. We'll see if it resolves by tomorrow.

Shipping was free, and 1 full kit and 2 bare bones were $25. I was of the impression that people have had to drill out larger holes, so I purchased a backup 1/2" as an unwilling test subject.

Now to find a 5 gallon bucket with a lid.


    Bookmark   April 4, 2014 at 3:48PM
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I was unable to ever get the Mazzei selector tool to work for me. But I found plenty of information in the performance tables publicly available.

    Bookmark   April 4, 2014 at 4:41PM
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The ebay ones from China don't fit US standard 1/2 pipe thread very well. You'll have to use a whole lot of teflon tape to get a leak-free seal. But, there apparently is enough thread overlap to be able to securely hand tighten.

It takes quite a bit of flow before the ebay injector begins to pull in solution. Setup on a typical bypass config on a 25 ft garden hose, and a multi-pattern sprayer. It would not pull solution on a "shower" setting, but would on "full" setting. Not impressed with the adjustable solution valve provided with the unit. It leaks air, so trying to adjust it down does not work. As soon as you restrict the solution with that valve, it pulls air in and therefore no solution.

    Bookmark   April 14, 2014 at 12:25PM
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Charina, I was having a great day until I read this (grin).

I am likely going to have low flow - drip hose or drip emitters.

Other than the cheaper eBay units, do any of these work correctly for my usage? If I'm out $25 for the 3 I bought to test, that's OK; I'm just not interested in spending $150 to get fertilizer into the strawberry towers.

I really don't like the EZ-Flo for the reasons above.

I find it interesting that the engineering tolerances are so off given the uniformity of a hose connection. Perhaps if I glue PVC and hose connectors to each end? That would make an air and water tight seal. Perhaps that would fix part of the problem.

They should be here next week, so I guess I'll find out if I have a hit or miss.

Thanks for the input.


    Bookmark   April 14, 2014 at 5:08PM
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Just a question on these.

Am I going to need to build/buy a bypass valve - ie 1 inlet of water broken into 2 streams; one stream to device; one stream bypasses. Both streams rejoined to go to plants?

I was planning on just having hose to device to hose to plants.

Am I approaching this wrong?

PVC is cheap, so the bypass is doable; I just don't understand (among a lot of things) the need/usage to get my task done.


    Bookmark   April 15, 2014 at 1:59PM
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The bypass provides for a level of control over the amount of injected material. You may not need one if the flow rate of your irrigation system is barely sufficient to operate the venturi anyway. The bypass is to reduce the amount of suction pulling in the material being injected by reducing the pressure differential between the inlet and the outlet.

The venturi principal works via differential pressure between the inlet and the outlet. Due this differential of pressure, combined with the restriction just before the entry point of the uptake inlet, a vacuum is created at the uptake inlet. The vacuum is created by a combination of the source pressure, and the terminal flow. This is why if your drip system does not provide for enough flow, the injector will not work. The backpressure from the drip system will be at or nearly equal to the source pressure. The level of flow just wonâÂÂt provide for a pressure drop at the injector orifice. A bypass wonâÂÂt help (itâÂÂs actually to compensate for high terminal flows), and opening up the orifice by drilling it out will not help (will make the injector less effective at low flow rates). The only two options are to decrease the injector size, or increase the terminal flow.

In response to an earlier question, the tubing to attach to the bottom of the injector, to pull the injected material has an inner diameter 7mm (just a tiny bit bigger than ü inch). ItâÂÂs a stiff hose, and a nice snug fit on the injector. You will have to dip it in hot water to get it soft enough to get it on the injector.

    Bookmark   April 16, 2014 at 1:24PM
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Andrew, this morning I had time to play with the mazzei 283 injectors. They are much smaller than the eBay ones and definitely work better for low flows. Whereas the eBay one would not work with a hose end shower sprayer, I actually needed to adjust the bypass with the mazzei to dial down the rate of injection while using the same hose end sprayer. It worked great.

I should have taken a photo down the throat of each one. That is where the size difference is most obvious.

    Bookmark   April 18, 2014 at 11:47PM
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Well this is good news.

I actually purchased two different sizes from China/eBay - 1/2" and 3/4". The actual 'models' were:


The mazzei 283 is defined as 'very low flow' and 1/2". Hopefully my 1/2" will be low flow and perform the same. Otherwise it looks like I'll be buying a 283. Of course, the 283 is +/- $40 from and not $5.

A place called has the 283 PP for $27.95 and the 283-NPVDF for $43.95 - any idea what the difference is (i.e. which would I want)? Do you have a low cost provider for these?

Any idea what the lowest GPM out the hose end is that creates suction with the 283? And what is the ratio that the tube pulls. I'd love a really low flow rate with a really high ratio, but I no longer believe in Santa Claus.

Is the blue one in your picture 3/4" or larger?

Thanks for the help - it's encouraging.


    Bookmark   April 19, 2014 at 12:34AM
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Did you make or buy that bypass valve?
I'm looking for an internet 'howto' with a parts list - do you have one?

I'll post a global request outside this thread, but since you have the picture, I figured you might have the answer.


    Bookmark   April 21, 2014 at 9:08AM
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I made the bypass. I just walk into the hardware store and envision what I need. No list. That particular one I made of all 1/2 pvc. So, one would need 1/2 pvc pipe, a ball valve, two T couplings, two slip x male threaded elbows, and two female threaded unions. Plus primer and glue. To fit mine to a hose, I needed a 1 male and 1 female hose connecter to pvc adapters. Just make sure that one of the last pieces in place is a section of pipe from a T to the ball valve. In other words, put the injector in place, and then determine the length of the final piece of pipe between the ball valve an a T.

The blue one in the photo I posted above was 1/2 inch, identical to the one you provided a link to. Significantly larger than the smallest mazzei.

The best price I was able to find on mazzie injectors was the source they linked to on their site. Kisko Sales

Playing with the 283 Saturday, I started to time how many gpm flowed through it, and how much it would take up, but someone decided to start a shower in the middle of filling a 5 gal bucket, so the flow rate changed with the pressure change. I didn't have time to start over and move everything over to the secondary irrigation source. But I did note that the flow exiting my hose may have been less than 1 gpm, and the suction rate was very high. Much higher than I expected. Emptied 1/2 gallon in a min or two. As I mentioned above, I definitely need the bypass to slow down the uptake rate, and provide reasonable flow for a hose end shower sprayer. Late Sat I was able to get it all setup with diluted sulfuric acid, dial in the bypass, and now my water coming out of the hose is a pH of 5. Perfect for the blueberries I need all this for.

You only need the cheaper poly propylene. I got one PP and one NPVDF. I will use the NPVDF when I setup the acid on an automated irrigation system, not this portable hose setup where I am using more dilute sulfuric acid. I donâÂÂt know that I need the NPVDF, but it does have higher chemical resistance and heat resistance, so when IâÂÂm using more concentrated acid in the irrigation setup, I wanted the more durable NPVDF to last longer. The mazzie salesman I spoke with convinced me there may be enough heat creation with concentrated acid injection that the NPVDF was a worth considering. For fertilizer, PP is more than adequate.

    Bookmark   April 21, 2014 at 11:01AM
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According to the eBay description, both my devices are BSP - duh!

I can't find a local source for the converters, but found that Dura Plastics makes them (one of the people I called is a dealer for duraplastics, but doesn't stock these and only orders in case sizes). This in turn brought me to the company which gave me part numbers.

This brought me to the Northeast sales rep and the phone number for a local distributor - I'm waiting for his return call.

In the interim, google became my friend (see link below).

The part numbers I was given are, for the 1/2" and 3/4" respectively: BS435-005 and BS435-007. These parts go from the thread to a PVC slip.

Anyone think this is wrong before I order a few of these?

Additionally, size shipping is brutal, anyone want a few of these and I'll send them along after increasing my order size? Charina, any interest?


Here is a link that might be useful: 1-888-PVC-FLEX - BSP Fittings

    Bookmark   April 24, 2014 at 11:04AM
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Fortunately, NPT and BSPT have the same thread pitch on both 1/2 and 3/4. Not so for most other sizes. So, really there is just a diameter fit issue. I solved that with a bit extra teflon tape. It held well enough, and was completely leak free on the 1/2 inch BSPT injector I played with for a while. I only tightened to 'hand-tight', but that level of 'hand-tight' might be as snug as others would ever go with a wrench on pvc. It was pretty darn tight. So, thanks, but no converters for me. Works adequately without them for me.

Before you order, you might verify that the slip end on a 1/2 male BSPT X female slip is the same size slip as US 1/2.

    Bookmark   April 24, 2014 at 3:32PM
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nil13(z21 L.A., CA (Mt. Washington))

I think I would just use putty epoxy to glue a pvc coupler on the ends instead of paying a bunch of money to ship a couple inexpensive parts.

    Bookmark   April 25, 2014 at 11:08AM
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So I placed an order from - Eric, who works there, must be a saint. He took several calls from me and explained all the stuff that I knew I didn't understand (although there's probably a lot that I don't know that I don't understand). I'll have enough parts to last me for decades. What started as an order for bsp adapters ended up including valves, hose connectors and even a new pvc cutter - I guess Eric's customer service had an economic benefit this time.

I attached the small venturi off the deck - this one is a quarter inch model from a2ozone. Unfortunately, it isn't pulling; I'll check to make sure I don't have it running backwards, but the water is flowing in the direction of the arrow. The deck plumbing pulls off the kitchen lines and there probably just isn't enough flow. I have a sprinkler connection for drip, so I'll try that and also bring out my water meter to check the pressure. I may just need to use the EZ Flo off the deck (gah!).

And the saga continues.


    Bookmark   May 2, 2014 at 9:16AM
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PFCMCL(z10 - S CA)

I'm new at this and was considering buying the Hozon Brass Siphon Mixer. The problem is my hose is 75' long. Do you have any suggestions for me?

Thanks in advance.

    Bookmark   October 13, 2014 at 1:18PM
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I was having some issues with understanding the venturi working. I would like to get maximum suction from my venturi and would like tot know some details

My Venturi is a 2" with 2" threads on both side.
Do I connect 2" piping on either side to get the best possible suction or lesser diamter piping

    Bookmark   October 26, 2014 at 7:50AM
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