Irrometer Tensiometers

[Savage Henry]

I'll find some info out on it. Makes sense why you would u

Totally, I'd appreciate that. Thanks.

 

[Savage Henry]

Alright, I got em installed. They were kind of a bitch to setup, but luckily there's a few YouTube videos of how to do it.

At first I used my core sampler to bore a hole in one of the pots but it was too loose and after a day i wasn't getting a reading. So I re-read the manual and it said that for highly aerated mediums to make a shallow hole and just shove the meter in the last two inches. So that's what I did.

The two pots with the meters installed were irrigated to runoff at 5pm last night, and then I shutoff just their drippers. The rest of the plants were irrigated again at 11pm, while I monitored the meters on the two. At 2am they hit 5kpa and I watered them by hand with 500ml from the Rez. Only about 100ml of runoff whereas the ones irrigated at 11pm got ~370ml and still had about 20% runoff. This is in coir that holds about 750ml (in 6in sq pots) at field capacity.

So the next step is to set my timer to coincide with the irrometer reading, let's say 5kpa for now. And weigh the pots at f/c and then again at each point of kpa up until it's almost dry.

I already want to get the gauges with the 12v trigger on em, just have to figure out how to make it click on a 120v pump for a set amount of time.

 

[Savage Henry]

Yea, man, definitely was overwatering, I knew it, I just couldn't put my finger on the cycles.

I'm happy to help, I heard about these things like a year ago and have really been digging into them for the last couple months, not gonna lie I was a bit giddy when I saw them working last night.

The fun part is going to be using them for crop steering, dryer for generative and wetter for vegetative.

 

[Savage Henry]

the AC 120v gauge might work if you only have one zone( all drippers come on at once)

Yea, man, I just run the one zone (benefit of mono-cropping, I suppose). I can't seem to find the one rated for 120v, only the 30v:

Pethaps I'm missing what you're describing?

The manufacturer info says "option a" can be rigged into a countdown timer, which sounds like what I should do.

Would something like this (http://www.lectrocomponents.com/pro...2z9CtZr5uV8geeUH3cj8Vq7SKyqUCdxoCwaAilP8P8HAQ)work? Or would I need to rig an additional relay so the 30v can trigger a 120v outlet?

What do you think, @Natural ?

Automation aside, these things are awesome, they really show any inconsistencies in ones environment, changes of a couple degrees can effect the readings of the gauge by a couple hours. I'm logging the readings so I can make predictions but the plants are growing so fast that my predictions aren't exactly reliable quite yet.

 

[Savage Henry]

Aha! Thanks, @Wentworth ! I went digging in that jackmayoffer thread and found this link:

Now to figure out how to run a couple zones, if I'm going to get an irrigation controller it should be able to control multiple rooms, or zones, so I'll need to get a pump relay for each pump! Dude, thank you, I've been googling this shit all day to no avail.

Edit: so the irrigation controller will need to be able to have an event triggered by a 30v input...

 

[Savage Henry]

Alright. So it looks like this irrigation controller will work for what I'm going for:
https://www.amazon.com/Galcon-6-Station-Irrigation-Propagation-Controller/dp/B00ES8NV88

Don't need 6 stations but it's cool to have the option there for whenever I get my shit together to expand.

So here's the plan:

- Wire the automatic tensiometer to the sensor port on the controller

-set the controller to kick on for x minutes as often as possible so as soon as the tensiometer hits a set point it'll trigger a timed irrigation cycle, allowing for some runoff

Now a concern is making sure when the needle on the auto-irrometer gauge falls below my chosen set point it doesn't interrupt the irrigation cycle, it only makes sure that another one won't be triggered until the appropriate time.

 

[Savage Henry]

About a week of irrigating at 5-6kpa:

I was shooting for a bit dryer root zone to encourage generative growth and therefore root growth, looks like it worked, a week ago the roots were just starting to poke out of the sides.

Looks like enough roots to start irrigating at 4-5kpa, and encourage some vegetative growth. Also, added about 10% more volume to each cycle because the runoff was fucking crazy when I sampled it from a couple pots 2.8-3.6ec, irrigating at 1.3ec. This shot up over the course of 2-3 days, when it was in the low 2s. I also diluted the Rez down to 0.8ec. So I should be able to lower the salt content over the next couple days.

 

[Natural]

ahh sorry didn't see this. Thread is taking off! Any controller with rain sensor input should work. Glad you got it figured out.
Just a question..if the set point falls below..wouldn't you want the irrigation to be interrupted..or is it that you want your run-off?

 

[Savage Henry]

ahh sorry didn't see this. Thread is taking off! Any controller with rain sensor input should work. Glad you got it figured out.
Just a question..if the set point falls below..wouldn't you want the irrigation to be interrupted..or is it that you want your run-off?

Yea, man, I have to allow for the obligatory 20% runoff. So what im trying to do is have the tensiometer trigger a times irrigation event whenever it reaches a set point. I was reading thru the instruction manual of the irrigation controller I posted above and couldn't get a definitive answer about if the sensor will interrupt a cycle or just not allow for any more.

Those are some fat roots - looks like a bowl of noodles;) I didn't know that bit about drier for generative/root growth wetter for vegetative or I guess never thought about it. I have noticed root growth explodes when medium is kept drier and the plants kept more moist stay greener n more healthy looking thru flower but despite looking more healthy they have smaller buds..... Now that u say that it makes sense they're(plants kept more moist) putting their energy into leaves and not as much into bud development hence the nice leaves but small buds..... Hmmmmm interesting :)

I haven't read anything in white papers that explicitly said that generative growth= root growth (not to say the research hasn't been done, I just haven't stumbled across it yet), but there's a great deal of anecdotal evidence pointing to it floating around the forums.

I posted a couple links about "crop steering" as its called in the "beds are for f***ing" thread over in the coco forum if you want to read up on it.

 

[Natural]

Yea, man, I have to allow for the obligatory 20% runoff. So what im trying to do is have the tensiometer trigger a times irrigation event whenever it reaches a set point. I was reading thru the instruction manual of the irrigation controller I posted above and couldn't get a definitive answer about if the sensor will interrupt a cycle or just not allow for any more.



I haven't read anything in white papers that explicitly said that generative growth= root growth (not to say the research hasn't been done, I just haven't stumbled across it yet), but there's a great deal of anecdotal evidence pointing to it floating around the forums.

I posted a couple links about "crop steering" as its called in the "beds are for f***ing" thread over in the coco forum if you want to read up on it.

Well, the rain sensor will over-ride the controller settings..so when it gets a signal from "the rain sensor" yes it will shut off. I'd put a call into Rainbird or whomever you are buying from and get a definitive answer on "during irrigation shut-off". All the literature and instructions claim.."skipping cycles".
Pots are tough..especially small ones. Almost want to skip over those and use the tensiometer signalling in the big pots...and maybe just use the gauge to better figure out your scheduling on the small ones.

read this..indicates that for small pots..you basically need a computer to do the watering vs a controller that inhibits cycles.


and then here..scroll down to programming
https://www.irrigation.org/uploadedFiles/Certification/Smart Technologies Final.pdf

this article seems to suggest tensiometer failing if soil completely dries out. Suggesting that almost constant trickle irrigation is what is called for
http://fshs.org/proceedings-o/1986-vol-99/51-56 (SMAJSTRLA).pdf


Personally, I don't see the point of employing automation using tensiometers in veg with small pots when irrigating to the point of run-off. I believe all the greenhouse small container trickle irrigation is done without run-off and they use the internet to use complicated software to control irrigation as compared to a sprinkler valve controller that will only allow the inhibition of the system to over-water.

 

[Savage Henry]

Well, the rain sensor will over-ride the controller settings..so when it gets a signal from "the rain sensor" yes it will shut off. I'd put a call into Rainbird or whomever you are buying from and get a definitive answer on "during irrigation shut-off". All the literature and instructions claim.."skipping cycles".
Pots are tough..especially small ones. Almost want to skip over those and use the tensiometer signalling in the big pots...and maybe just use the gauge to better figure out your scheduling on the small ones.

read this..indicates that for small pots..you basically need a computer to do the watering vs a controller that inhibits cycles.


and then here..scroll down to programming
https://www.irrigation.org/uploadedFiles/Certification/Smart Technologies Final.pdf

this article seems to suggest tensiometer failing if soil completely dries out. Suggesting that almost constant trickle irrigation is what is called for
http://fshs.org/proceedings-o/1986-vol-99/51-56 (SMAJSTRLA).pdf


Personally, I don't see the point of employing automation using tensiometers in veg with small pots when irrigating to the point of run-off. I believe all the greenhouse small container trickle irrigation is done without run-off and they use the internet to use complicated software to control irrigation as compared to a sprinkler valve controller that will only allow the inhibition of the system to over-water.

Great reads, man, thank you. I especially liked the one about citrus irrigation in Florida, there are definitely some issues to look out for.

I'm going to flip these in the next couple days, part of me wants to leave them in these pots and see what happens, but I'm leaning towards hedging my bets and transplanting them up into 2 gal fabric pots as this will invrease an acceptable margin of error.

You make a great point about the smaller pots, seems my best bet would be to use a short cycle timer and adjust it as needed. I may just get the galcon controller I posted above and a pump relay. It looks like I can just rig the 24v pump relay input as if it's a solenoid.

 

[Natural]

Great reads, man, thank you. I especially liked the one about citrus irrigation in Florida, there are definitely some issues to look out for.

I'm going to flip these in the next couple days, part of me wants to leave them in these pots and see what happens, but I'm leaning towards hedging my bets and transplanting them up into 2 gal fabric pots as this will invrease an acceptable margin of error.

You make a great point about the smaller pots, seems my best bet would be to use a short cycle timer and adjust it as needed. I may just get the galcon controller I posted above and a pump relay. It looks like I can just rig the 24v pump relay input as if it's a solenoid.

correct..both the relay and solenoids both operate via 24v signal. Unless you want to run multiple zones via solenoid operated valves on the same pump...then you would use the relay tabs for the pump. Keep us updated as I'm slightly behind you..wanting to run several small pumps. I was going to use a simple timer for mine as it's just vacation mode operation and not fully auto'd..but at the same time curious as to how the controller would do with multiple pumps. What kind of pumps will you use?

 

[Savage Henry]

sitting on coco mats in a tray jungleboys style. You get the benefit of unrestricted lateral root growth

So THATS what the coco mats are for! I wouldn't be able to make them work in my current setup as I elevate the pots off the basement floor with clone trays. The floor is on a slight angle so the runoff goes into the sump hole and periodically gets removed by the sump pump whenever the float valve engages.

This is supporting my inclination to transplant up pre-flip.

correct..both the relay and solenoids both operate via 24v signal. Unless you want to run multiple zones via solenoid operated valves on the same pump...then you would use the relay tabs for the pump. Keep us updated as I'm slightly behind you..wanting to run several small pumps. I was going to use a simple timer for mine as it's just vacation mode operation and not fully auto'd..but at the same time curious as to how the controller would do with multiple pumps. What kind of pumps will you use?

I'll be using the same old submersible pumps I have been for a while now. Ones a little giant and ones a cheap-ass harbor freight job. My rooms are pretty small, 10x10 and 12x14 so the pumps are able to maintain enough pressure to ensure even flow out of pressure-compensating drip emitters.

That said, I've been eyeballing either a leader or grundfos (?) pump since I started running drippers a year ago. While they would be able to maintain enough pressure for octabubblers they'd be waaaay overkill for my scale.

The more I think about this the more it looks like ill leave off the automation and irrigation controllers for now and stick with my old standby programmable plugin timers. One can plug in 20 on/off times which should be more than enough as the plants are currently being irrigated 2x/day and I doubt they'll be asking for any more than 6x by the end of stretch, especially if I transplant.


So I re-read the whitepaper I linked at the beginning of the thread. The ec spike i mentioned earlier has to be a direct reault of letting the pots dry out more than necessary. This paper and the one linked by @Halosmoker point to optimum irrigation set points under 5kpa. In fact, here they are referencing uc mix which has a far lower air holding capacity than coir:

So it looks like I should be shooting for something more like 3-4kpa as a set point.

 

[Savage Henry]

There was a guy on here had one gals coco on coco mats said the root mass under the mats raised his pots by nearly an inch it acts almost like nft under the mat plus the roots grow through the mat as well....

I just read something said transpiration of coir-grown plants started to decline only at tensions around 4.5 kPa but also said they watered at around 3 kPa so as you said 3-4 sounds ideal in case some pots are drier than others gives you some leeway... Man I can't wait to get mine now..... I know I'm overwatering ......and underwatering lol. I'll probably just use it manually til I setup a watering system hopefully I still can w the auto gauge

I'm stoked to see how they work for you, sir!

It's looking like 3 kpa might just be the sweet spot, at least for the brand of coir I'm working with. you make a good point about covering ones that drink a bit more and those that drink a bit less. The instructions said to install it in a plant that transpirates a bit more than average, and I also have that plant in a spot in the room that gets *almost* the most light.

I cleaned em up and took some clones. It was cool watching the transpiration slow as the foliage was removed over the course of the day (I did it in two sessions). Tomorrow is the first day of 12/12 and I figured fuck the transplant, fortune favors the bold!

 

[Savage Henry]

Hell yea, man. Find your flow and let it ride. I did flip some small pots once before and had root rot and a bunch of other nonsense go on and they still stacked like a motherfucker. So with a healthy root mass I bet sky's the limit. Just have to stay on top of IPM and cleanliness.

Sounds like we have similar viewpoints, I just mentioned my ocd in a thread the other day, lol. I'm in the room every couple hours checking runoff volume ec, ph and of course, now tensiometer readings. Getting this shit dialed.

 

[Savage Henry]

Alright, some observations:

After irrigating the readings will sit at 0kpa for a few hours then once it starts going up the speed grows seemingly exponentially. It's like a bubble popping.

I've been irrigating at 3kpa, plants are getting 2-3 cycles a day of about 500ml each. Subtracting runoff they're transpirating roughly 0.8-1.2l/day.

They transpire (or it just evaporates) quite a bit overnight! The meter showed me 0kpa at lights off. 12.5hrs later they were at close to 10. I really don't want to have a cycle during lights off, I should schedule the final irrigation closer to lights off, maybe an hour before.

I saw a couple gnats on the sticky traps and did a full on drench with gnatrol right at lights off. This slowed transpiration significantly, they didn't get to 2kpa until 4-5hrs into the next light cycle.

It's cool watching the ec fluctuate throughout the day. The first irrigation tends to have a fairly high runoff ec and by the end of the day it's in an acceptable range. This further points to overnight evaporation.

@Wentworth did you get yours yet?

 

[Savage Henry]

Been working quite well for me so far. About to bump up to 6 irrigation cycles a day from 5. And it looks like I'll need to add a cycle during lights off. The last irrigation has been an hour before the lights go out and when they come on the reading is at 6kpa, which causes an ec spike.

I've found that I need to lightly tap the side of the tensiometer to make sure the reading is accurate, but other than that they work great.

How are things going for you, @Wentworth ?

 

[FarmerX]

Great thread guys! Ordering mine this morning; would you recommend the MLT or LT model for 5-10 gallon medium?

Thanks in advance!

X

 

[Savage Henry]

I think either one would do you just fine -depending how deep your containers are. Would suck if it's too short tho. I got the 6" LT works great in 20s. I wanna get a few more thought I'd be able to change pots w ease but it's a lil tricky to get set/working right plus it's pretty thick you can feel it murking roots when you push it in

Glad to hear you have em up and running!

I've found that if you put em in a new/different pot if you irrigate the plant after the install then wait 4-24 hours they start working again.

 

[FarmerX]

http://www.specmeters.com/assets/1/22/Tensiometer_QuickStartGuide.pdf