The DFT hydroponics build #1 that has been discussed previously has been fully operational for a while now and it seems like a good time to go over the system as a whole. It is tagged as a DFT or Deep Flow Technique due to the standing water within the tubes that is more than a mere film as would be found in traditional NFT or Nutrient Film Technique grows. It could just as easily be called SFT or Shallow Flow Technique but I have seen similar examples labeled DFT.
The build itself has seen several crops of lettuce and basil already and currently hosts rapidly maturing pepper plants as well as herbs and salad greens. After using this unit for multiple crops I can say it is best suited for salad greens and herbs. Larger plants such as pepper plants eventually grow a root mass that leads to leaking in the future.
The video below gives a good complete overview of the system without too many minute details. If you want the specific details as well as plans, drawings, additional photographs, and parts lists then I suggest visiting the download link found at the end of this article or click on the eBooks / Plans link.
The video mentions the power consumption of the magnetic induction lighting which is 200 watts. The entire setup uses about 250 watts and that includes a shared air pump that also powers the tiny aquaponics build nearby. The pumps run continuously but the lights run about 16 hours so power consumption is even less. The magnetic induction lighting is nice because it is quite efficient and is supposed to last 10 years.
The polyethylene plastic shelf of this unit was added later to make use of left over materials from the reservoir lid (be sure not to use plexiglass to cover a water reservoir as it will warp). The current use of the shelf is going to be for sprouting micro greens as there seems to be enough extra light getting through and if there is not then it will be easy to mount a small fluorescent above as needed.
The build is still expandable as needed. I intend to some day mount a Blue Lab Guardian PH / TDS monitor on the wood support to better manage the nutrient solution but for now I will make due with a handheld meter. If tubes with a different hole spacing were ever needed it would be rather easy to make new swappable tubes I could thread into place. When it comes time to do a complete system clean I can run a bleach solution through the unit and the tubes could be detached and better cleaned as needed.
I found that the outflow tube going back into the reservoir should be submerged into the water in order to avoid creating more of an odor in the room. When running a shallower nutrient solution I simply added a PVC elbow to keep it under the water and the odor subsided. Moisture alarms were placed on the ground around the DFT hydro system to alert us in the event of a leak but have so far never been needed.
My overall impression of this Deep Flow Technique DIY hydroponics project is overwhelmingly positive. It makes great use of the light from the window, uses a reasonable amount of electricity, and has grown a wide variety of different plants successfully. After having tested its capabilities it will most likely grow salad greens and perhaps a few herbs. It is about the right size to have a fairly steady supply of pesticide-free nutrient dense salad on a regular basis. It is a very rewarding feeling to take two steps from your kitchen to harvest clean produce that you know exactly what was put in and put on it.
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