NFT is the style of system that we use in the greenhouse for all the lettuce’s. NFT stands for Nutrient Film Technique and describes the feeding system for the plants. We fill the reservoir with rain water or RO (reverse osmosis) water which is the purest water with a TDS (Total Dissolved Solids) of around 0 ppm (parts per million). It is important not to have any elements in the water before adding your nutrients as it will be unclear to what is already in the water. (For example: tap water is full of chlorine, fluoride, and numerous pharmaceutical drugs as well as toxic waste, all which are poisonous to our plants, as well as us!)
Once we have filled our reservoirs with water, we then add the nutrients. For the lettuces and herbs, we use a Grow formula which is high in Nitrogen which plants require during their vegetative (or growth) state. Since lettuces and herbs do not need to flower for consumption, we only need to use this one formula, we just increase the strength as the crop grows bigger. We did purchase a crop specific nutrient from the manufacturer of the system, American Hydroponics, but have not begun to use it yet. We’ll update you when we do.
Back to NFT, now we have our water and nutrients mixed and the system is running. Nutrient Film Technique sort of speaks for itself. The water/nutrient solution is pumped to the “top” of the system and then uses gravity to flow down the gutter. This creates a “film” at the root zone soaking the media (we use rockwool, as this is the most efficient media for the NFT system). The water then flows into a gutter at the “bottom” of the gutters and drains back to the reservoir, creating a recirculating system.
So we’ve been keeping you up to speed with how awesome the NFT is doing on the back porch, now time to give you a little behind the scenes. We couldn’t be happier with our first run and growing on a large scale and we were doing it the easiest way we could think of.
Typically with a hydro system, you want to change your reservoir every week. It is recommended to you RO water (reverse osmosis) which should have a ppm (parts per million) of 0. Tap water generally has a ppm of about 200. When you use tap water with a ppm greater than 0, what this means is there are particles in your water that might not necessarily be beneficial to the plants, or even worse, could be harmful.
How did we do it to start? We took the garden hose, running city water and stuck it in the system. After we filled it up, we through some nutrients in and made sure that our ppm’s were around 800 (accounting for the city water). We let it rock out, and just monitored the ph every day. The ph climbed every 24 hours, so every morning we had to dump in some ph down to keep it at the level that we wanted. When the water level got low, we put the hose in then adjusted our ppm’s. That’s all we did, and you’ve seen the growth we got.
6 weeks in to our growth, and we decided to actually change the reservoir over to RO water. We did 35 gallons of RO water and then 25 gallons of rainwater (which usually has a ppm right around 0; if it doesn’t register that’s good). Then, we added our nutrients. We’ve been using the Dutch Master A and B for this first run, with a little bit of Liquid Karma and some Hygrozyme. Once we had our water at 60 gallons, we added 500mL of the A and 500mL of B. (After you add a nutrient, it is important to check your ppm. Let the system run. Since this one is a large system we give it a few minutes, but smaller systems should register faster.) We then added 300mL of the Liquid Karma and 300mL of Hygrozyme. After checking our ppm we were sitting at about 600 which is between quarter and half strength.
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