My system was operating smoothly for the past couple of months (using DFRobot EC and pH boards with parasitic insulator, Apera instruments EC and pH probe, and Atlas PT-1000 temp probe… all in I2C).
A few nights ago it started going crazy and after rebooting the I2C went offline. Had to disable and re-enable it to start it back up, but it started having some off behavior. See the asynch graph below. Anyone has any idea what this could be? Or any recommendation on what to try? System is outdoors, but it is inside an enclosure protected from the elements.
Pi? Power issue? One failed sensor fouling the others? I’m only running Atlas pH and PT-1000 off my Pi3 with T3 board. I know I’m due to down the system and bring everything indoors to calibrate since my PT-1000 has been inaccurate for months.
I am running a RPi4b. I do not think there was power issues as of late. I am using the rpi power supply, and it is all mounted on a surge protector too. The temp sensor seems to be behaving well, I think the pH/ec sensors are the ones that might be acting up. I had to recalibrate them and restart the pi multiple times until they were back online giving reasonable data…
After a few days, the behavior started again. I purchased an Atlas lab-grade pH probe to see if it is the probe. I will update a few days after it arrives and gets installed
Get rid of the Atlas pH sensor and just test your pH by hand every day or 2 using pH strips or pH drops. If you’re using proper buffered pH up and pH down solutions then your pH should not fluctuate too much over a day or 2 period. If it is, then there is something else going on that you need to fix. There are very few pH sensors that are designed to be used continuously, and the ones that are, are very expensive and simply not worth it when there are simpler, cheaper, more traditional options than a sensor.
There is also no real reason to measure EC. If you are mixing your nutrients according to the manufacturer’s recommended ratios, then you should not have to worry about EC. There is absolutely nothing you can do to change the EC reading except add fresh water to dilute the nutrient solution anyway, so it’s really not a useful or meaningful measurement of anything other than the electrical conductivity of the nutrient solution which approximates the Total Dissolved Solids in that solution… anything you add to the solution other then fresh water will only raise the EC reading… and temp fluctuations will also cause wide swings in the EC readings… this is why having your system outdoors is not recommended, temperature fluctuations will cause changes in your pH and EC readings. If you have no control over the temperature in the grow space or the reservoir, then you really aren’t doing “hydroponics”, you’re just doing “drip irrigation”. Temperature control is one of the most important factors in controlling many other aspects of a hydroponics system such as relative humidity, VPD, pH, EC, etc.
I have a pH and EC sensor because I have a water line connected to top off my reservoir automatically. So whenever the level goes down, I add nutrients back in to keep my plants fed the nutrient level I want.
The pH sensor I use from Apera Instruments is ~$40 and has been working just fine. It has been working for more than 6 months without a recalibration. I am happy with that and I think it is well worth not having to add water/nutrients/ph down to the system every 3 days (that’s why I got Mycodo). I found the culprit and there was some root debris that was touching the sensor membrane and throwing everything off. I added a coarse filter on the return to prevent this from happening again.
The temperature is not an issue for the EC reading as I use a temperature probe to compensate. Again, that’s the whole point of adding the mycodo environment to my setup. The pH measurement does not fluctuate significantly with temp, but still gets its compensation.
I do it outdoors because I do not want to run lights, RH, etc. that increase the operational cost. I run it on a vertical soil-less tower, so that is pretty much a hydroponic system to me (low-pressure aeroponic if you want to be a purist). I do not control my res temperature and it still works pretty well, measured by the amount of delicious tomatoes I harvest. It’s space efficient, saves me from dealing with soil, and I have it running without maintenance. It might not be the most optimal temperature or plant growth but I do not care for that. My plants and I are happy
That’s not how it’s usually done. Pretty much all nutrient manufacturer’s instructions tell you to mix your reservoir at the recommended levels and then NOT add any more nutrients until you are ready to mix a new tank… the only thing you should add between new tanks is fresh water and pH adjustment.
Every time you add anything to the tank besides water, the EC will rise. Any time there is evaporation or transpiration from the reservoir, the EC will rise. Pretty much EC will always be in a rising condition. Adding water will correct this, but adding more nutrients will NOT keep your nutrient ratios the same… this is because when water evaporates, nothing goes with it… so your nutrient levels will always be getting more concentrated as the water evaporates, and your plants are not taking up enough nutrients to compensate for the water loss, so when you add more nutrients along with the fresh water top-off, you are only increasing the EC reading again. You will eventually end up with a nutrient solution that is over-feeding your plants and causing nutrient problems… this effect is increased when growing outdoors due to lower humidity and increased evaporation and transpiration.
Again, I do not care the ratio is not optimal and I mentioned that in my previous post. The plants take up nutrients and water, and the res gets topped off with fresh water, so the EC will go down. I dispense nutrients at the mfg recommended ratio to bring the level back up. It’s not optimal and I do not care about that, because plants grow and thrive. I have a variety of different plants on the same nutrient reservoir so there is no magical nutrient-balanced formula that works. My interest is to have the system running with zero or minimal input from my side, and it does that. If I see nutrient deficiencies I can do a reservoir change and start fresh again.
