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NFT vs DFT
Hello, I'm planning on setting up another small system upstairs to grow herbs/veggies over the winter. Should I use NFT (nutrient film technique) or DFT (deep flow technique)? Basically, 4" PVC for DFT, or vinyl rain gutters for the NFT. What are the differences, if any, between the systems?
Replies to This Discussion
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Permalink Reply by RupertofOZ on
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Simplistically... the only difference is the volume, and height of the water flow...
In reality... with DFT it is mandatory that you aerate... although I advocate doing so even in NFT...
Both require that the water be pre-filtered...
Even in hydroponics, I never really saw the benefits of DFT in comparison to NFT... other than say for tomatoes, peppers...
As it just meant more water/flow... bigger pumps... bigger net pots... more aeration... more nutrients.... = more costs...
Aquaponics alters those equations a bit... and PVC pipe might be cheaper than NFT channels... but if it's only lettuce, herbs and most veges... indoors... then I'd just go NFT...
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Permalink Reply by David Hart on
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Yesterday, I pulled apart someones 3 inch NFT's ...to give you an ides of the size, thats a 12 oz soda can sitting next to the roots. They were from some basil.
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That's pretty normal for basil... if you push it for any lenght of time... like this...
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Wow, looks like those are the 'real' NFT tubes, with the removable lids....very nice. The pipes are a lot harder to clean out...
I personally don't care much for NFT's (outside), the system's water tempts swing fast depending on the air tempts. My buddy and I are working on a design to overcome those problems. When I get a chance...I'll have to start a post with what we are working on...
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Permalink Reply by Killian Griffin on
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Thanks for the info guys. Looks like I'll be setting up an NFT system in the next few days.
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Permalink Reply by David R. Russell on
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4" is definitely the way to go for DFT. Roots clog and impede flow too quickly with 3" and smaller. Especially basil. 3" ok for lettuces for a couple of months. A DFT design that worked well used an airlift to continuously aerate and circulate the water. Two horizontal 4" dia pipes with 2" holes for baskets. Two 90s at end to connect the two horizontal pipes on one end (max length of 10' for horizontal pipe). The other end of horizontal pipe reduced down to 2" with a 90 pointing down on one and a tee on the other 4" pipe end. Both with about 2' of two inch pipe going down towards the ground and connected to each other at the bottom with two 90s. Looks like two pvc "U's" One horizontal for growing plants and one U vertical for airlift function. Unit can be supported over boards to create a level platform. An airstone is placed down open hole of tee to create airlift . Water flows up 2" pipe of tee, flows down the horizontal 4" pipe with plants, rounds the corner of the two 90s and then comes back the other horizontal pipe with plants and then down the 90 to 2" pipe and then back up the airlift. System is flooded just like deep raft, but the flow is fast but requires little energy as airlift is just circulating not really lifting much. New water from AP system can be introduced to the loop and an overflow to return excess water back to the fish. In event of power loss- Roots are still sitting in water and plants survive. Nice for a small operation or for going vertical with multiple tiers. Still think that deep raft is more economical for larger operation. Unit works well. Seen it first on the web for hydroponics "titled ten green thumbs" California based, but site seems to have disappeared. Referred to it as nutrient stream technique. Oh- and another nice feature is that the greater water volume will help buffer temperature swings. If temp is a big issue, there is no reason why the vertical U for the airlifts couldn't be longer and burried in the ground to use geo-cooling.
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Permalink Reply by Hydroponics Curacao on
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I like the NFT. It is very easy to make and doesn't cost a lot. If you have some very good filter, you wouldn't have roots clogging. My system has been working for about 1 month already. The water has Cycled before I even started the system. And I never had any problems with roots clogging. Plants are growing really fast and healthy.
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Sound good so far H. Curacao. What have you planted in the NFT?
I'm considering using it for strawberries.
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Right now I have 2 lettuce plants, 6 scallions, some basil and those types of carrots that stay small. I also tried planting a tomato plant in there for testing. In total in can carry 16 plants right now. Currently designing a new system that can hold 70+ plants. In that one I'll be adding some strawberries.
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Permalink Reply by Hank Paloci on
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@Rupert, I'm looking at this pic you posted back in January 2012 of what looks like basil growing in square (or rectangle) vinyl gutters. I was wondering what you're using as end caps and how you keep the flow even among the gutters. When I run grow beds parallel the flow always ends up uneven and it's high-maintenance.
In a couple of weeks I'm going to be looking to set up for spring (which comes early in SoCal) and I'd like to do something like what you have along the south side of my house.
FWIW I haven't seen much benefit in DFT but that's based on my space limitations. I think you just go with what works for you.
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