In another thread I mentioned that I would soon start a new trial in hydroponics and – for everyone’s information and comment – this is what I have in mind doing: Nutrient film technique (NFT) is a hydroponic technique developed in the mid 1960s, wherein a very shallow stream of water containing all the dissolved nutrients required for plant growth is re-circulated past the bare roots of plants in a watertight gully, also known as channels. In an ideal system, the depth of the recirculating stream should be very shallow, little more than a film of water, hence the name 'nutrient film'. This ensures that the thick root mat, which develops in the bottom of the channel, has an upper surface, which, although moist, is in the air. A properly designed NFT system is based on using the right channel slopes of 1:30 to 1:40, the right flow rate of 1 liter per minute, and the right channel length which should be less than 10 – 15m. The main advantage of the NFT system over other forms of hydroponics is that the plant roots are exposed to adequate supplies of water, oxygen and nutrients and is – consequently - the most productive form of hydroponics. Ex: Wikipedia This is - almost exactly - what I have in mind building.In an effort to supplement plant nutrients, I originally had in mind to install a filter in the bottom reservoir and stock it with fish to produce food-waste that can be converted to plant-growing nutrients. However, that would force me to do regular measurements of the nutrient concentrations in order to maintain the correct levels for the plants under cultivation but that will – obviously – make the fish superfluous. So I eventually decided to leave out the fish but keep the filter.
Now I am in a pickle. The only shop that was selling plastic rectangular down pipe, has recently closed business. Now I must decide if I can get this type of down pipe posted to me - in short lengths - from CT or JB. Or . . . switch to a different method such as the "Deep Water" (DW) culture. But that requires a floating foamed PU platform, and the one shop that used to sell those in sheets closed its business a few years ago. You can't win this war so easily.
Hi @Greystoke. Ive seen them at Builders Express, Penny Pinchers and Burmeisters here in East London.
@mattie. The "NFT"system relies on a shallow stream of nutrient solution to maximize air exposure in order to maintain a high oxygen level. Obviously, a round pipe would be the worst selection when trying to achieve this. Therefore I went for a rectangular profile to encourage the flow to spread out across the width of the pipe. But, I am yet to try it out. I must tell you that I tried your system with round pipes at maximum solution flow a few years ago with strawberries. Unfortunately is was not very successful. @Waldip, Looks cute and it would probably work well for some plants, but I don't think that it can be adapted for a larger production level. But . . . you never know until you try it.
I've seen on tv where they have these vertical farms they grow greens in, and they use a certain type of fish(a lot of them), they use their shit as nutrients basically, also form what i could see they only used blue and red LED's.
I think that I've seen the same on TV. The fish were Tilapia and the blue and red LED's are the most effective light sources. Adding any other light colour just to make things more attractive only makes the system less useful.
