43 days after making a clone, blooming, algae problems

A project log for GrowInBox

A box that fits in a room, in which plants can be grown.

DomenDomen 10/28/2015 at 19:260 Comments

It's been 43 days since I've pushed the runner in the rockwool cube and 21 days since the strawberry was in my hydroponic system. The system itself went through some changes as you can see below. Firstly I used an ultrasonic humidifier to make the mist, but it heated the water so I switched to a deep water culture system. Also note, that ultrasonic humidifiers may not be okay for aeroponics, because the droplets may be too small! More about this below.

The main two ideas were:

I wanted to use an ultrasonic humidifier for making the mist, which was wrong!
Not only does the mister heat the water to 36°C (96.8°F), the droplets may also be too small.

NASA research has shown that plants are more willing to absorb nutrient water in 5 to 50 microns droplets more effectively than any other sizes. Water droplet size is crucial for sustaining aeroponic growth. Too large of a water droplet means less oxygen is available to the root system. Too fine of a water droplet, such as those generated by the ultra-sonic mister, produce excessive root hair without developing a lateral root system for sustained growth in an aeroponic system. (Source)

I've checked here that the ultrasonic mist water droplet is about 1 micron in size.
But then, there are people who claim that it works fine.

I will write about aeroponics and my ideas for it in a future log, for now, I'll just document what I've done so far and how it worked out.

I decided upon only 2 compartment system without the water pump because it was simpler. I used polymorph because it was at hand and it's cool because you can melt it with boiling water and reuse it as much as you want.

After sealing the plastic to the container I still had some water leaking, but I didn't really care. I just wanted to finish everything that evening (7th of October).

The fan pushes air into the system.

The aluminium plate with LEDs fits tightly between the shelf holders and I've also tied it with wire wrapping wire - the best investment of my life.

Although I would recommend you get slightly thicker wire, because I can still tear this wire apart fairly easily with my hands and that's why I have to use more wires in parallel.

I'm using 5x10W cold white LED chips in parallel, connected to 12V from the ATX power supply. I chose cold white LEDs because they produce more plant-usable light.


The water solution consisted of 50% strength TNT complex (Hesi) and 50% strength root stimulator (Biobizz). I also added some SuperVit (Hesi) which contains vitamins and minerals. For pH down I used ascorbic acid, (vitamin C).

I bought 100g in powder form for like a euro or something, although I'm not sure it's the best chemical for pH down, since the pH came up almost every day.

I ran the humidifier quite irregularly. Some days I'd turn it off over night and some days I'd let it run all the time. I also thought about and UPS for the ultrasonic mister and a timer, but I never got to actually automating anything. I was really lazy about that. I had an idea thought.

This is the root grow from day 25 do 32.

And this is the top growth from day 24 to 43. Some days I took two pictures.

This is a photo from the 33rd day. Those little roots fell off when I pulled on them. And I pulled really softly! They must have rot or something. Maybe the mist was at 36°C and therefore too hot for the roots.

Healthy strawberry roots (source):

On the 7th of October (day 22) the roots looked normal and strong.

When looking at those photos I realize what was meant in the quote on top of this log:

Too fine of a water droplet, such as those generated by the ultra-sonic mister, produce excessive root hair without developing a lateral root system for sustained growth in an aeroponic system. (Source)

On day 33 I threw together a deep water culture system in a mason jar because the aeroponic one was smelling like ammonia and I deeply care for my strawberry and I thought it was better to think this through than to kill her. Also the first system was leaking from the bottom :D. The solution was the same as the last time.

But because the mason jar is clear and well oxygenated ...

BOOM. Algae. This was only 2 days (day 35) later.

5 days later (day 40) ...

Today, day 43. The rock wool cube transformed into algae wool mush .. Ugh ..

In the past days PPM kept falling and the pH was coming back up to 7 every day, even though I would add vitamin C to lower it. The light was usually running for about 16 to 17 hours a day. I've read that 14h is ideal for strawberry, but it seems to grow just fine with more hours.

I really need to change the reservoir and clean everything and add a new solution ... I'll try to do that ASAP. I have also ordered a digital pH meter from aliexpress sincer the readings would be more accurate.

“Live as if you were to die tomorrow. Learn as if you were to live forever.” - Gandhi