beyond thankful for this video, quick question is there a way to have my code translate the mv from the calibrated sensor to the moisture percentage or do you always have to plug it into that equation ??
You could speed up and more thoroughly dry the media if it wasn't placed in the beaker, reducing the evaporative area of the sides of the net pot. Perhaps a petri dish or glass bowl would be better. Depending on the sensitivity of the scale, a fan blowing in the vicinity, but not directly at the apparatus, could also help reach the dry media endpoint.
Thanks for your comment! Good question! Check all the sensor dry and fully wet readings, for sensors that give +/-5% readings the calibration is bound to be similar, but for sensors that have +/-5% differences, best thing would be to calibrate them separately. You can however, calibrate many sensors at the same time using a single scale since you can put many sensors in a larger media container.
I use ecowitt moisture sensors for my garden and I've found them horribly inaccurate. Bumping them even slightly will dramatically alter the reading. Changing to a different part of the pot changes the reading. Changing amounts of nutrient in the media I believe also modifies the reading. Do the sensors in this video perform well regardless of position in the media container? Do they perform well even if firm contact with the soil has been lost due to media shrinkage etc? I religiously use mine, but I have to constantly take notes about what value means what. At the beginning of a season, I calibrate, and know to irrigate at 65%. A month later I might need irrigation at 40%, 20%, or 80%. It's really frustrating. I've searched for hours and hours for an alternative product that performs well and does not cost a fortune.
Thanks for commenting. It is definitely not an easy thing to do, because the media itself is not homogeneous in terms of moisture content. The sensor placement plays a key role in determining how reliable it will be, placing sensors closer to the center of the pots and closer to the crown of plants will tend to give more reliable readings. However, none of these sensors are perfect, all of them require recalibration if you want to interpret absolute readings. A better way to use them, especially when irrigation is concerned, is to use the highest to lowest point delta to trigger irrigation events, rather than absolute values.
If you maintain the substrate moisture at a constant saturation % and do not allow the substrate to cycle between dry and wet, will the plant suffer? I've always been under the impression that in irrigated hydroponics the dryback is necessary to give the roots an opportunity to breathe. I'm assuming that the O2 that follows the oxygenated nutrient solution is not enough all on its own. Thoughts?
Thanks for commenting. Certainly, you can do that. For example, you can have a substrate like perlite, with very low water retention, where you drip irrigate the substrate at a consistent rate permanently. The substrate cannot get overwatered and cannot wick more water than necessary and the flow rate ensures the ideal moisture is maintained. Other substrates like rice hulls or expanded clays can be used similarly. We don't do this often in practice though, as these systems are very vulnerable to failures in irrigation. A system where constant moisture is maintained requires a constant source of water, such a source can be interrupted, which can kill the plants. Since the optimal constant moisture is closer to dryness than full saturation, failures to irrigate these substrates imply quick dryback and plant damage. It is much harder to do this in substrates that have high moisture retention, because they will naturally wick and retain water aggressively, so your watering rate would need to be very low and hard to adjust. In practice what you mention is only done with very low moisture retaining substrates.
@@ScienceinHydroponics I understand how this would work with constant irrigation solutions because the oxygenated solution is replenishing O2 in the media, rinsing out the solution with depleted O2. I suppose I'm talking about situations where runoff is minimal, such as wicking containers where the capillary action of the substrate governs the saturation % and does not fluctuate. I have an automated system which attempts to reach runoff and dryback every day, but I think it would be much easier to set up the system to pulse irrigate all day long to maintain the saturation within a tight band. However I assume this would result in low oxygen situations. I could be wrong? Can O2 permeate substrates like coir enough that the roots can passively breathe if the saturation is below 65% or so?
@@SetTheCurve It is doable, but you will need to adjust very tightly to plant uptake and evaporation to prevent low oxygen situations. You basically would water to just ideal saturation (which is going to be on the dryer rather than wetter side to allow for air pockets for oxygen uptake), then just replace the amount by doing very low volume irrigations consistently. The volume of these irrigations needs to almost perfectly track plant uptake needs as the plant grows. Another point is that you will need to custom design your solutions so that you have minimal nutrient accumulation in the media. If your solution is not properly designed and nutrients are accumulated then the plant will inevitably suffer through time as the chemistry of the media losses balance.
Struggled with getting those capacitive sensors working.
Now i ordered such scale and will try your method, thanks!
Looking forward to seeing more Arduino/Raspi/MyCodo videos!!
Thanks for commenting! We're working on an "Arduino from scratch" series, focusing on people in hydroponics who want to get into this.
@@ScienceinHydroponics yes! Please do.
beyond thankful for this video, quick question is there a way to have my code translate the mv from the calibrated sensor to the moisture percentage or do you always have to plug it into that equation ??
You can have the equation incorporated into your code to make things easier.
You could speed up and more thoroughly dry the media if it wasn't placed in the beaker, reducing the evaporative area of the sides of the net pot. Perhaps a petri dish or glass bowl would be better. Depending on the sensitivity of the scale, a fan blowing in the vicinity, but not directly at the apparatus, could also help reach the dry media endpoint.
Thanks for commenting and making suggestions!
Would one need to calibrate each individual sensor separately if you buy multiple of the same sensor, or can you use the same formula for each sensor?
Thanks for your comment! Good question! Check all the sensor dry and fully wet readings, for sensors that give +/-5% readings the calibration is bound to be similar, but for sensors that have +/-5% differences, best thing would be to calibrate them separately. You can however, calibrate many sensors at the same time using a single scale since you can put many sensors in a larger media container.
I use ecowitt moisture sensors for my garden and I've found them horribly inaccurate. Bumping them even slightly will dramatically alter the reading. Changing to a different part of the pot changes the reading. Changing amounts of nutrient in the media I believe also modifies the reading. Do the sensors in this video perform well regardless of position in the media container? Do they perform well even if firm contact with the soil has been lost due to media shrinkage etc?
I religiously use mine, but I have to constantly take notes about what value means what. At the beginning of a season, I calibrate, and know to irrigate at 65%. A month later I might need irrigation at 40%, 20%, or 80%. It's really frustrating.
I've searched for hours and hours for an alternative product that performs well and does not cost a fortune.
Thanks for commenting. It is definitely not an easy thing to do, because the media itself is not homogeneous in terms of moisture content. The sensor placement plays a key role in determining how reliable it will be, placing sensors closer to the center of the pots and closer to the crown of plants will tend to give more reliable readings. However, none of these sensors are perfect, all of them require recalibration if you want to interpret absolute readings.
A better way to use them, especially when irrigation is concerned, is to use the highest to lowest point delta to trigger irrigation events, rather than absolute values.
If you maintain the substrate moisture at a constant saturation % and do not allow the substrate to cycle between dry and wet, will the plant suffer? I've always been under the impression that in irrigated hydroponics the dryback is necessary to give the roots an opportunity to breathe. I'm assuming that the O2 that follows the oxygenated nutrient solution is not enough all on its own. Thoughts?
Thanks for commenting. Certainly, you can do that. For example, you can have a substrate like perlite, with very low water retention, where you drip irrigate the substrate at a consistent rate permanently. The substrate cannot get overwatered and cannot wick more water than necessary and the flow rate ensures the ideal moisture is maintained. Other substrates like rice hulls or expanded clays can be used similarly.
We don't do this often in practice though, as these systems are very vulnerable to failures in irrigation. A system where constant moisture is maintained requires a constant source of water, such a source can be interrupted, which can kill the plants. Since the optimal constant moisture is closer to dryness than full saturation, failures to irrigate these substrates imply quick dryback and plant damage.
It is much harder to do this in substrates that have high moisture retention, because they will naturally wick and retain water aggressively, so your watering rate would need to be very low and hard to adjust. In practice what you mention is only done with very low moisture retaining substrates.
@@ScienceinHydroponics I understand how this would work with constant irrigation solutions because the oxygenated solution is replenishing O2 in the media, rinsing out the solution with depleted O2. I suppose I'm talking about situations where runoff is minimal, such as wicking containers where the capillary action of the substrate governs the saturation % and does not fluctuate.
I have an automated system which attempts to reach runoff and dryback every day, but I think it would be much easier to set up the system to pulse irrigate all day long to maintain the saturation within a tight band. However I assume this would result in low oxygen situations. I could be wrong? Can O2 permeate substrates like coir enough that the roots can passively breathe if the saturation is below 65% or so?
@@SetTheCurve It is doable, but you will need to adjust very tightly to plant uptake and evaporation to prevent low oxygen situations. You basically would water to just ideal saturation (which is going to be on the dryer rather than wetter side to allow for air pockets for oxygen uptake), then just replace the amount by doing very low volume irrigations consistently. The volume of these irrigations needs to almost perfectly track plant uptake needs as the plant grows.
Another point is that you will need to custom design your solutions so that you have minimal nutrient accumulation in the media. If your solution is not properly designed and nutrients are accumulated then the plant will inevitably suffer through time as the chemistry of the media losses balance.