NFT vs. 12" Grow Beds

[Josh Graybiel]

Hello Everyone!

I was hoping to get some input about the pros and cons of grow beds utilizing the nutrient film technique vs. 12" grow bed filled with clay media. Specifically the advantages one may have over the other.

 

From what I gather, the clay media provides a filtration benefit, but I am curios about the effects this might have on water quality.

 

The NFT technique would require an additional component of some sort of settling basin/filtration. From reports out there, this removes all of the particulate phosphorous which is 80%, but not the dissolved phosphorous 20%. Does this greatly inhibit the NFT production?

 

Thanks for taking the time,

 

JG

[TCLynx]

The primary benefit of Media beds VS NFT is that the media beds do multi duty functions

1-they are the plant space and they support the plants

2-they provide bio-filtration surface area

3-they provide solids filtration space (without the need to remove solids from the system and do regular cleaning of filters)

4-they provide solids mineralization space and worm homes to help with that mineralization

 

NFT doesn't provide any of those except for maybe part of #1

 

Now I know there are overly high tech systems out there that do NFT and have all the other parts dealt with using high tech, high maintenance filtration elements and most of those systems seem to grow mostly lettuce and a few herbs so phosphorus is probably not that big a deal to them.

 

For the other NFT set ups I know of, They are used more as add on plant space in a media bed system where the media beds are used to filter the water and take care of 1-4 and a clean water sump catches that filtered water and it can be pumped to the NFT pipes and so the phosphorus isn't lost in those set ups since the solids are being retained in the system.

 

However I do know that in my NFT and Raft bed add on to my systems, the plants NOT in the media beds seem to show more problems with nutrient deficiencies than the plants in the gravel beds of the same systems.

[Josh Graybiel]

Thank you TCLynx for your insight.

 

What are your thoughts on the deep water culture?

Friendly design seems to work quite well, however, I have no idea how the fecal matter is filtered...or is it? It seems like they blast the culture tank with air so there is no fecal matter settling.

 

Thanks again!

[TCLynx]

For the Friendlies commercial systems they have settling tanks and net tanks to collect the solids so they don't go to the raft beds.

 

For commercial operations Raft aquaponics can work well though I've never had much luck with it when I have tried.  I have very hard well water and all my plants seem to do best when they are in media than in the raft bed or NFT pipe.  If my water were not so challenging perhaps I could do better with those but I haven't been willing to get an RO filter and I don't seem to be collecting enough rain to keep up with all my systems.