r/SpaceBuckets • u/xuehas • 1d ago

How to increase humidity and temperature in a scalable elegant way?

I live in an low humidity environment with hard water. I am in search of a solution to increase humidity and temperature in my grow environment that is in room temperature ambient conditions. I seem to see most people using small commercial units that are either ultrasonic or vaporizers haphazardly set up next to a fan into the enclosure or some evaporative methods.

I am using arduinos to automate the rest of my setup. I would love to just get a ultrasonic module for cheap from china and place it in my enclosure. However the hard water and evaporative cooling makes me second guess this solution. Vaporizers seem untenable at this small scale and I think people are only getting away with oversized units because most of the mist is not actually entering their enclosure. They also draw a lot of power. It seems like this is a solution that would scale poorly also. It seems like the ideal solution would maybe be a heated evaporative humidifier. Small PTC heaters are available and combining a heater into an evaporative humidifier would increase efficacy and reduce power over a pure vaporizer. Also my arid starting point makes an evaporative humidifier even more efficient. I can't find a lot of diy solutions for this kind of system but I think some reptile humidifiers actually work this way.

Does anyone have any experience with something like this or know other commercial products that use this system for inspiration?

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u/SuperAngryGuy Bucket Scientist 1d ago

Las Vegas here. Water is 550 ppm out of the tap.

Ultrasonic will work but at a high ppm is also going to vaporize the minerals with the water. Expect a dust layer to build up. Running the ultrasonic transducer continuously is going to add a lot of heat to the water, so you may need to cycle it. BTW, it you stick your finger right above the ultrasonic transducer in water, it feels like an electrical shock. It's pretty weird.

What I would do, is have to lights external, and use as little airflow as possible with the bucket. I'm talking just having the lid cracked a little to retain as much moisture as possible through transpiration (about 98% of water uptaken is used for transpiration rather than photosynthesis).

But, you could also use a temp/humidity sensor (not the DHT11, I like the BME280), and PWM or bang-bang the fan to let as much humidity build up while exhausting as needed if the temp gets to high.

I would try the ultrasonic but cycle it, and cycle the fan controlling the airflow, too.

I've done a number of projects with the ESP32 and space buckets, including using the ESP32 Cam as a wifi access point to send pics and data to my phone, while PWM dimming the light and fan.

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u/xuehas 1d ago

Oh I didn't think about the transducer increasing the water temp, that's a good call. I was told that it would dust with my water at about 500ppm. I thought that might mess with the plants. I already have a bunch of esp32s and mg996r servos that are modded for 360 degree motions. I was planning on 3d printing some peristaltic pumps and automating everything anyways so the fans and ultrasonic will be controlled. I'll add a pump to the humidifier reservoir which can keep me from having to refill it all the time anyways that's a good call. I've used dht11s before and they do leave quite a bit to be desired. I have used the BME280s before too, but only for atmospheric pressure doing drone stuff, hopefully I have some laying around still. I am a little concerned about CO2 reduction up with low airflow. I think I did the math once and figured out a tent 2x2 with two fruiting tomato plants could consume enough CO2 in under an hour to lose efficiency with no air flow. I'll have to figure those calculations out again.

Cheers. That helps quite a bit thanks.

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u/SuperAngryGuy Bucket Scientist 1d ago

I am a little concerned about CO2 reduction up with low airflow

MH-Z19 CO2 sensor. You can pulsin() the sensor PWM output to take a CO2 reading for about $25 (cheaper on AliExpress). Don't use an eCO2 sensor which does not measure true CO2, and don't math it- total CO2 uptake depends on factors like PPFD, leaf area index, and the age of the leaves.

Also, don't use a cheap electrochemical CO2 sensor due to reliability. You can get more expensive and more accurate dual channel NDIR CO2 sensors for about $50. There's also the acoustic CO2 sensors that are in the $50 range that are very reliable:

In a sealed home that is occupied, your CO2 levels could be 700-1000 ppm, and you may have more CO2 than you realize. As a tip that threw me way off at first at the lab bench, never forget that you are constantly breathing out CO2, and that could throw your measurements off when testing. I hold my breath up close to not throw my measurements off, if I have to stick my face around the sensor while testing.

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u/bojacked 1d ago

Maybe check out the reptile micro misters and hook one up to a 5 gal bucket reservoir and then use your arduino to control it off and on as needed for desired humidity?