By continuing to use the website or clicking Accept you consent to our cookies and personal data policy and confirm that you are at least 18 year old. For details please see Privacy Policy and Terms
After my first entry into the solo cup challenge with a container full of rock wool, it became clear that the small 473 ml (16 oz) root zone needed to be 100% available for the roots alone. Otherwise, the plant will become stunted and stressed which causes early onset of the flowering response. The rock wool solo was 20% the size of the same seed batch with the same nutrients with an ample container size for the root zone.
This mini hydroponic set up was made with transparent containers for visual observation of the root zone and nutrient reservoir with pump and air supply to the root zone... just for the added element of fun.
The root zone container was double walled so before using the Dremel tool to route the hole for the bulk head attachment for drainage, I drilled a small hole for injection of two-part epoxy into the space between the walls to avoid any potential cracks when screwing the bulkhead tight. In hindsight this was not required as the walls were relatively thick and strong.
Once the epoxy set up I used the Dremel tool to route out a 32mm hole for the external threads of the bulkhead to slide thru and secure on to the lid with the nut tightened up underneath. The 10mm straight male barbed pipe attachment was then screwed into the internal threads of the bulk head to attach the nutrient pump supply tube.
The nutrient solution supply pipe includes a "tee" between the pump with a reducer to accept the 6mm air supply tube which is directed up into the bottom of the root zone with a small round 20mm air stone which also serves to prevent the roots from entering into the pipe and escape the confines of the root zone container.
A small pump with flow control dial is attached to the pipe for supplying the nutrient solution with a continuous interval on/off timer with cycles capable of 1 second.
The screw on lid was routed to accept a small rock wool cube on top.
The demo clips show how the nutrient and air supply are being delivered to the root zone. After the flooding of the root zone to the top of the container, the pump turns "off" and the nutrient solution simply drains back down the supply pipe and out of the pump intake, which in effect, has now has become the outlet :)
Day 35 to 37 is showing rapid hydroponic growth. The roots are getting very dense at the bottom of the container. There is much less tendency for the roots to grow up into the available space. This makes it more difficult to crack loose and raise the root mass from the bottom of the container.
The roots have become too dense for the air to flow up. The path of least resistance is to go back down the nutrient supply tube which prevents the pump from being able to prime itself. The air bubbler is now in the nutrient tank for a simple flood and drain system.
Nutrients are being changes every 2-3 days due to water consumption. Ideally the nutrient concentration remains more or less the same as the water level drops but I am not able to maintain optimum health as seen in the video. I tried a number of different brands and concentrations with not much in the way of improvement. It's amazing how the mood is effected when the plants are not doing perfectly well. Its can be quite upsetting :/
After experimenting with various brands of nutrient formulations and concentrations.. the plant is showing improved health. The root zone has become too dense for consistent flood levels even with the same number of seconds for the pump ON cycle. The solution is now fed through the pipe which is reduced to the smaller feeder line to fill the nutrient solution at at the top of the container which is gravity fed back into the reservoir. The original air stone is used to prevent the roots escaping the container and entering into the nutrient tank solution. The only way to remove the roots is to let them dry out and shrink enough for easy withdrawal from the container. The video shows very slow drainage due to the barbed pipe attachement beging submerged below the top of the nutrient level. It was removed to facilitate quicker drainage. I just noticed that I swore in the video as I was still playing with the timer ON setting and had to quickly unplug the electricity manually in order avoid an overflow... 😂
More of the same as the buds continue to fatten up. However, foxtails are beginning to show and I prefer flowers with dense calyx formation. So I prepare to harvest a bit early for a light clean high rather than the more stoned effect of fully matured cannabinoids.
The plant of course is much more smaller with the restricted root zone causing a bonsai effect. However, she performed really well under the circumstances with a relatively large yield all things considered. I usually smoke high CBD but was very impressed with this high. Let's see how it goes after spending more time under the influence.
Review...
Growing in the solo cup sized container proved to be much more challenging than a regular grow. The plant soon became stressed dealing with the tiny root zone making everything hyper sensitive. The first issue was showing as tip burn even though the ppm was kept in the 650-850 range. Then the leaves showed a general yellowing overall specially showing at the bottom fan leaves. At this point I was changing the nutrient solution every 2-3 days trying different nutrient brands and concentrations seemingly without much success. It was a nerve wracking period which ultimately lead me back to General Hydroponics with amendments. I did learn that the plant can weather the storm even with less than perfect vegetative leaves while she focuses all her energies into calyx production. It’s was upsetting to see less than stellar health but eventually all the leaves drop and the flowers power on seemingly without issue.
The cascading diamond structure developed as a result of a couple broken branches that occurred during the training process in an effort broaden the plant profile with wider lateral spacing. Although initially upset when the fractured branches that withered after being bandaged up and . After removal of said branches it was exciting to see the new possibilities. The cascade formation called for additional side lighting to maintain uniform bud size all the way down the front lower end of the plant. I was looking to create a stadium like effect.
The experience of operating the visual hydroponic unit called for a number of practical adjustments along the way. Although initially, very excited with the system concept as an integrated design with nutrient solution supply and gravity drain through the pump, with the air supply inside the pipe with the air bubbler acting as the drain/root filter... in hindsight, obviously, it would not work as the root mass became denser and denser. The first issue, as the path of least resistance, the air was forced back down the nutrient supply pipe. This prevented the pump from priming itself and subsequently no nutrient solution delivery was even possible. As a result, the original air stone was left in place to prevent the roots from entering the nutrient tank and a new bubbler stone simply added to the tank itself.
Although the original idea was for the air to be continuously pumping directly through the roots, the flood and drain would actually be just as good when drawing the fresh air in and out with each pump/drain of nutrient solution. The ON cycle was initially set to 10 seconds which eventually became 30 seconds as the roots mass grew denser. This proved to be too unreliable as the fill level was no longer consistent which required constant monitoring to be sure that there was no flooding over and above the container lid. It which case, a simple feeder tube to the top of the root zone was the best option. The ON cycle was set to 5 seconds with a 15 minute OFF interval. Overall the biggest concern was the timer itself, which had several bad reviews for malfunctions with growers losing their plants. However, I have no choice as this was one of the few timers that was capable of cycling down to the second but it all workout fine in that regard… no problem.
Was it a perfect grow?... no, definitely not. However, as a relative beginner, it was definitely a great learning experience. Mostly, I need to work on the nutrient blend and concentration. For more control, a backup tank with float valve delivery to maintain the water level for this particular system would be a good idea as well.
Stealthman
