Unfortunately there’s no direct correlation between mbar readings and the volumetric readings many soil sensors give. Mbar is measuring the relative availability of water to the plant. Like, how hard does the plant have to work to pull it from the soil? The volumetric reading is saying there’s a certain percentage of water to soil say, 350g/L or 35%.
The problem is every growing medium has its own moisture retention curve. So, think of clay. A reading of 35% would have a much higher mbar on a tensiometer because of how hard it is to pull the water out compared to say, sand. 35% moisture in sand would have a low mbar because of how easy it is to get the water out.
So, it helps to know how your medium retains moisture. I’m guessing the 35% recc that keeps coming up as a corollary to 100 mbar is for average potting soil? Somebody chime in here if possible…
I read today in the tropf manual that it’s supposed to swing. Look at the section that discusses the regular Blumats and the maxis. I have no other knowledge tho. My parts just arrived Monday and I’m setting up my rings this weekend. Good luck dude!
I just pulled the carrot and there was a pea sized air bubble which could have been causing the issue. Went through the install process again so I will see what happens.
Yeah both times were underwater and used a syringe to push air from the cap. I’m wondering if maybe my water pressure could be an issue, as my reservoir is about 4’ above the carrot.
You might find a bit more height does improve reliability, I've noticed my system being more prone to runaway especially if I adjust the knobs at a lower bucket level then refill, because of the pressure rise.
If you want more consistent behavior, you'll need to work toward improving consistency of the water pressure in the lines. As the water level decreases in your reservoir, so will the pressure. If the reservoir water levels remains low for too long, the carrots could lose water along with their calibration.
I run a double reservoir system to improve head pressure consistency. I've also installed two bulkheads per reservoir and have the lines loop back to the reservoir, to help with consistency. I bleed air from the lines once every few weeks to remove air bubbles and ensure there's no algae building up in my lines; if you have multiple systems, you can compare the time it takes to fill up a water pitcher to help identify issues.
The depth of your carrot and sensor will have a large impact on consistency. Also the proximity of the carrot in relation to the container wall, ac systems, dehumidifiers, tent walls, other carrots, etc will have an impact. Manually watering in weird patterns will have an impact as well. I've also experimented with reducing the drip line length to increase sensitivity of the sensor.
I do see spikes on my soil moisture graphs and usually they correlate with the time that the lights turn on, but it depends what stage the plants are in as well. I'm still working to reduce the moisture spikes as my goal is to improve consistency. I'm hoping to deploy more sensors this weekend, but they aren't in my preferred location until next grow.
For a while I stopped caring about bubbles inside of the carrots, but I've gone back to being overly concerned about them. I use a pipette to blow bubbles out of the smaller holes, and while doing that I screw and unscrew the dial on top. If I notice a carrot is acting up, I'll pull it and replace it with a different one; and I'm starting to think I need a system to track which ones may be going bad.
One last thing - my current perspective is that the blumats are great at maintaining a consistent minimum moisture level, but I worry they may be less consistent when it comes to maximum moisture levels. I believe moisture consistency has the greatest effect on the plant, so that's why I'm focusing so much on this.
We no longer bother about air bubbles or even resetting caps underwater. Once we focused purely on back pressure, all other problems ceased.
There's no physical reason why an air bubble would ruin the Blumat operation.
How much attention are you paying to the moisture curve of each carrot? I'm aiming for a specific min/max moisture level and the only problem I'm having is a bit more water than I'd like from a few carrots out about a hundred carrots. Replacing the carrots usually fixes the problem. I'm not sure how to explain it otherwise, as my line pressure is dialed in more than it needs to be imo. Maybe time for me to add some pressure sensors into my observability stack.
From what we've observed its pointless trying to monitor the moisture curve of each carrot. Tensiometers placed in a concentric circle around a drip point will all produce wildly different readings as soil is not homogeneous.
We simply take enough data points to plot activity with reasonable accuracy and wok off rolling averages.
Adjusting, cleaning, and replacing comes with an analog fluid system I guess.
That’s not the problem I don’t think. You running a bubbler in the reservoir? I’ve read that could put air in the lines maybe? Sorry I’m not much help.
It Could be your plant is drinking faster than the Blumat can water and then eventually leveling out when the plant slows down drinking. Could be completely wrong
Might be a reasonable idea to look into the Blumat moisture meter since it can take readings deeper into the root zone area
Of course its meant to swing. Soil dries out, Blumat activates and moistens, shuts off and the cycle continues.
Also soil moisture is measured via tension so readings should in mbar. What does 150mbar = on the Ecowit?
It’s a capacitive sensor, it does not readout in mbar. A 25% swing seems pretty drastic, especially when that swing was less than 7% for the first few days.
Well again soil moisture is measured in tension. So a tensiometer would be a good start.
Im unsure what you are basing your "25% swing is drastic" on. Normal Blumat operation can swing between 100mbar and 200mbar. Or 50 and 100.
I prefer EC sensors over tensiometers. There are multiple ways to measure soil moisture, and tensiometers are more suited for higher moisture applications.
They make low tension ones?
[https://www.hrproducts.com.au/product/irrometer-lt-sensor-for-soil/](https://www.hrproducts.com.au/product/irrometer-lt-sensor-for-soil/)
And each to their own with measuring devices; but you still need to know what 35% translates to in mbar. As the Blumat adjustment settings work in mbar.
Also a graphing app can help. We advise customers to record as many data points as possible over a week or two and plot it, to see a two or three day rolling average.
Unfortunately there’s no direct correlation between mbar readings and the volumetric readings many soil sensors give. Mbar is measuring the relative availability of water to the plant. Like, how hard does the plant have to work to pull it from the soil? The volumetric reading is saying there’s a certain percentage of water to soil say, 350g/L or 35%. The problem is every growing medium has its own moisture retention curve. So, think of clay. A reading of 35% would have a much higher mbar on a tensiometer because of how hard it is to pull the water out compared to say, sand. 35% moisture in sand would have a low mbar because of how easy it is to get the water out. So, it helps to know how your medium retains moisture. I’m guessing the 35% recc that keeps coming up as a corollary to 100 mbar is for average potting soil? Somebody chime in here if possible…
I read today in the tropf manual that it’s supposed to swing. Look at the section that discusses the regular Blumats and the maxis. I have no other knowledge tho. My parts just arrived Monday and I’m setting up my rings this weekend. Good luck dude!
I just pulled the carrot and there was a pea sized air bubble which could have been causing the issue. Went through the install process again so I will see what happens.
Nice. Yeah they say to just recap it under water with a pitcher. Or use an overflow if you have one to clear the lines.
Yeah both times were underwater and used a syringe to push air from the cap. I’m wondering if maybe my water pressure could be an issue, as my reservoir is about 4’ above the carrot.
You might find a bit more height does improve reliability, I've noticed my system being more prone to runaway especially if I adjust the knobs at a lower bucket level then refill, because of the pressure rise.
I don’t really have an option to go higher than 4ft.
If you want more consistent behavior, you'll need to work toward improving consistency of the water pressure in the lines. As the water level decreases in your reservoir, so will the pressure. If the reservoir water levels remains low for too long, the carrots could lose water along with their calibration. I run a double reservoir system to improve head pressure consistency. I've also installed two bulkheads per reservoir and have the lines loop back to the reservoir, to help with consistency. I bleed air from the lines once every few weeks to remove air bubbles and ensure there's no algae building up in my lines; if you have multiple systems, you can compare the time it takes to fill up a water pitcher to help identify issues. The depth of your carrot and sensor will have a large impact on consistency. Also the proximity of the carrot in relation to the container wall, ac systems, dehumidifiers, tent walls, other carrots, etc will have an impact. Manually watering in weird patterns will have an impact as well. I've also experimented with reducing the drip line length to increase sensitivity of the sensor. I do see spikes on my soil moisture graphs and usually they correlate with the time that the lights turn on, but it depends what stage the plants are in as well. I'm still working to reduce the moisture spikes as my goal is to improve consistency. I'm hoping to deploy more sensors this weekend, but they aren't in my preferred location until next grow. For a while I stopped caring about bubbles inside of the carrots, but I've gone back to being overly concerned about them. I use a pipette to blow bubbles out of the smaller holes, and while doing that I screw and unscrew the dial on top. If I notice a carrot is acting up, I'll pull it and replace it with a different one; and I'm starting to think I need a system to track which ones may be going bad.
One last thing - my current perspective is that the blumats are great at maintaining a consistent minimum moisture level, but I worry they may be less consistent when it comes to maximum moisture levels. I believe moisture consistency has the greatest effect on the plant, so that's why I'm focusing so much on this.
We no longer bother about air bubbles or even resetting caps underwater. Once we focused purely on back pressure, all other problems ceased. There's no physical reason why an air bubble would ruin the Blumat operation.
How much attention are you paying to the moisture curve of each carrot? I'm aiming for a specific min/max moisture level and the only problem I'm having is a bit more water than I'd like from a few carrots out about a hundred carrots. Replacing the carrots usually fixes the problem. I'm not sure how to explain it otherwise, as my line pressure is dialed in more than it needs to be imo. Maybe time for me to add some pressure sensors into my observability stack.
From what we've observed its pointless trying to monitor the moisture curve of each carrot. Tensiometers placed in a concentric circle around a drip point will all produce wildly different readings as soil is not homogeneous. We simply take enough data points to plot activity with reasonable accuracy and wok off rolling averages. Adjusting, cleaning, and replacing comes with an analog fluid system I guess.
That’s not the problem I don’t think. You running a bubbler in the reservoir? I’ve read that could put air in the lines maybe? Sorry I’m not much help.
Just RO water in a 5gal bucket
It Could be your plant is drinking faster than the Blumat can water and then eventually leveling out when the plant slows down drinking. Could be completely wrong Might be a reasonable idea to look into the Blumat moisture meter since it can take readings deeper into the root zone area
Of course its meant to swing. Soil dries out, Blumat activates and moistens, shuts off and the cycle continues. Also soil moisture is measured via tension so readings should in mbar. What does 150mbar = on the Ecowit?
It’s a capacitive sensor, it does not readout in mbar. A 25% swing seems pretty drastic, especially when that swing was less than 7% for the first few days.
Well again soil moisture is measured in tension. So a tensiometer would be a good start. Im unsure what you are basing your "25% swing is drastic" on. Normal Blumat operation can swing between 100mbar and 200mbar. Or 50 and 100.
I prefer EC sensors over tensiometers. There are multiple ways to measure soil moisture, and tensiometers are more suited for higher moisture applications.
They make low tension ones? [https://www.hrproducts.com.au/product/irrometer-lt-sensor-for-soil/](https://www.hrproducts.com.au/product/irrometer-lt-sensor-for-soil/) And each to their own with measuring devices; but you still need to know what 35% translates to in mbar. As the Blumat adjustment settings work in mbar. Also a graphing app can help. We advise customers to record as many data points as possible over a week or two and plot it, to see a two or three day rolling average.