Greenhouse foggers

[Tyrone]

I've just ordered some Netafim Coolnet greenhouse foggers to install in my tunnel. If they turn out good, I'll install them in my greenhouse, and maybe even through my canopy in the garden at specific points. Is anyone using this product?

My tunnel is set up with 24 cheap yellow misters, but the droplet size is too big, and they pump out 60l/hr each. With the Netafim's I've ordered I'd probably only need 4 crosses, and as each cross only puts out 20l/hr with a very fine fog, my consumption will go down from 1440l/hr to 80l/hr. Of course I don't leave the present system on for an hour, just a few minutes a day, and in the hot weather the heat sensor kicks them in at 32C, but there output tends to overwater things. With the Netafim foggers I'd have to leave the water on for longer so everything stays moist, and the heat sensor will act like an intermittent mister when things get to 32C and more, but hopefully, I won't be overwatering. I may be able to keep the humdity more constant too.

So for those who have tunnels and greenhouses, how do you keep everything humid, but not soaking wet all the time?

Best regards

Tyrone

[Tad]

I use the netafim 4 way mist nozzles on a phytotronics brand timer the prop haus also has a 4 foot tall by 40 fot long cool cell (swamp cooler) and 2 large fans that draw air thru!!

[Tyrone]

Thanks for the picture Tad. Look at them go. I can't wait to get mine in and set them up.

Best regards

Tyrone

[Tad]

I will take some good pics in the morning and post them, a few "what not to do" pointers too!!

[joe_OC]

I was just at Ralph Valez's house yesterday and he showed me the fogger he uses for his greenhouse. He has it on a timer and it kicked in while we were there...pretty cool how the "fog" travels through and puts a layer of water on everything in there.

[Neofolis]

I have the foggers from Mist King in Canada. I use them mostly to regulate humidity, rather than for watering, although, they don't have to be on for long for everything to be very wet. I use the cycle timer from Mist King, which allows me to set a duration on and duration off. In order to stop things getting very wet, I have to have the duration on set to 10 seconds or less, which allows most of the water to be absorbed into the atmosphere. The duration off needs to then be at least 5 minutes, so that the air is not saturated when they come on again.

You have seen the results of my trying the misters on for longer timings, although the salt toxicity problem I had was not so much the result of the misters creating the build up, but the fact that I was not having to water regularly and hence not flushing the salts out of the pots. Obviously the amount and type of misters, the internal temperature, the outside humidity and how well insulated the tunnel is, as well as the distance from the misters to the plants will all affect how wet the misters make things.

I think with misters that create very small droplets, they are not as good for watering, because although they can make things wet, they do so with a very small amount of water, so the plants get very wet without the water penetrating the soil very much. Of course with the misters on for considerably longer timings the run off from the foliage will eventually be sufficient to drench the soil.

Another problem that I have experienced in the past, prior to using RO water, was a build up of calcium deposits on the foliage. This may be a problem, if you have hard water. My normal water supply has TDS of 290-310 ppm, whereas the RO water has only 2-3 ppm. The calcium deposits create more of an aesthetic problem at first, but if it gets too bad, it eventually prevents photosynthesis and causes leaves to burn.

In terms of maintaining humidity, this will obviously vary totally depending on individual setup, but for my situation, if I have the off duration set to 5 minutes I get the following humidity levels.

Duration On

4 seconds = 45-60% RH

6 seconds = 55-80% RH

8 seconds = 65-90% RH

10 seconds = >70% RH

12 seconds = >75% RH

This varies slightly depending on external conditions and other things, such as how high I have the temperature set inside the tunnel, how much ventilation I am allowing etc., but you can see that with a five minute interval between spraying, just a couple of seconds makes quite a difference to the relative humidity. Also, at 4 seconds, everything, including the floor remains almost permanently dry, whereas at 6 seconds the floor is permanently damp, but the foliage is mostly dry. By 10 seconds or more, most things a permanently wet.

I know your situation will be totally different, but I thought this information may be of some use.

[Tyrone]

Thanks Tad, Joe and Corey for your input. It's very much appreciated.

My tunnel is not a heated one, it's totally "solar" against a NW facing wall of my house. In the middle of winter, the temps can get into the mid to high twenties celcius during the day, and on the coldest nights it adds about 6C to the ambient temps, so the coldest it gets is around 7C in there. Of course in summer, when the temps are 40C and above it needs extra help to stay cool and around the 32C mark. The roof is on a steep angle back to the house wall with a gap at the top which vents it. Also it's not air tight. Really gusty weather can allow some air movement in there. The gap at the top helps in summer to create a convection draft effectively sucking in cool air and venting it near the top. Also when the temps are forecast to more than 28C, I open the door during the day, and shut it at night to seal in the warmth and humidity. The house wall keeps it toasty in there at night in summer, so the mins hover around the low twenties C. Frogs love hanging out in there on summer nights.

The water quality appears to be fine with the present setup, but I don't know how much dissolved calcium is in it. If I have too with the new fogger setup, I'll put in a fancy disk filter or something. I'll have to do a bit of experimenting with the system, but I can have the foggers come on for a predetermined time for watering purposes then let the heat sensor take over in hot weather to keep the temp to 32C. I've found with the present setup even on a 45C day, the system has no problem keeping the temp to 32C. In that situation the sprayers may come on for two minutes and stay off for 20 minutes, and the humidity seems to stay in check. That's probably because humidity and temp are correlated together. 45C is a very rare occurence even here, so mostly the heat sensor may kick in 2 or 3 times a day for a minute or so on a hot day. The unfortunate thing, is it tends to overwater, although things like my Arenga's and Carpentaria's go nuts with the hot swampy conditions.

So hopefully my Netafim's will keep the humidity in check without turning everything into a mangrove swamp. Maybe I should grow some Nypa in there.

Best regards

Tyrone

[Tyrone]

Here's a view of the inside of the tunnel from a while back, but it gives a good idea of what it is. You can see the gap at the top of the roof. Ignore the sprinkler heads against the wall. They've been removed. Now I have a 20mm pvc pipe running centrally along the roof for the water supply.

Best regards

Tyrone

[freakypalmguy]

Hi Tyrone,

What kind of heat sensor do you have? I'm looking for something economical but have not found one yet.

Matt

[Tyrone]

I'm using a thermostat that is adjustable. I can't remember the manufacturer, but it's basically a switch connected to thermo tube via a copper pipe. It's the same sort of setup used in refrigerators and other appliances. You just need to get one in the 0-40C heat range. Basically when it triggers, it shorts the power from the retic transformer directly to the solenoid valve, bypassing the controller. The adjustability is very nice with the dial on the front. I then just wrap the whole thing (except the sensor tube) up in two plastic bags to keep it dry, with the sensor tube dangling somewhere out of direct sunlight amongst my pots. There is no danger with the system because it's all low voltage.

I just searched on google for it, and found a local electronics supplier who had it. It cost me about $50AUD.

Best regards

Tyrone

[Neofolis]

I've found pet supply places and reptile or terrarium specialists often have decent, reasonably priced thermostats available in a variety of configurations.

[Tyrone]

Well my greenhouse foggers came in today, and I couldn't wait to install them. Here's some pics for those who are interested.

[Tad]

make sure you put a fine micron filter in front of your line, those lpds dont clean out if they get clogged!

[Tyrone]

And here it is running. The mist is really fine and it wets the foliage nicely. This new arrangement uses 24 X 5 litre/hr emitters vs my old system that used 33 X 60litre/hr emitters. So I've gone from approx 2000 litre/hr down to 120litre/hr. Of course I'd never run it anywhere near an hour. One minute which is only 2 litres and everything is rehydrated again. I'm really happy with it.

Best regards

Tyrone

[Tyrone]

make sure you put a fine micron filter in front of your line, those lpds dont clean out if they get clogged!

Thanks for the info Tad.

Best regards

Tyrone