Concept design for an (cheap?) aeroponic NFT system

[Kobus Jooste]

After a little bit of head scratching and comments from others on the forum, I have a first concept drawing of what I'm wanting to add to my system.  The idea is that it will operate on very little water and thus will not mess too much with my water levels in the main FT.

 

The system of 4 x 4 m 110 mm pvc pipe will be able to house just over 50 net pots (30 cm intervals).  It will not be closed in, but rest on a base framework of wooden poles to lift it just above FT height.  The cover structure will be a 40 mm pvc pie and couplings design inspired by a number of set-ups I've seen on the forum.  A choice of shade net for summer and plastic for winter is considered as coverings.

 

 

Inside each pipe is a smaller (20 mm) pvc pipe drilled with two or three small (2 - 4 mm) holes at the position of each pot.  The idea is that water flow will be just enough to wet the pots, containing a wicking material.  Roots should hopefully not get into the supply line.  Water will come from a 2 x filtered (box and inline) water supply sources from a main FT overflow / bottom valve.  The pump will be on timer. 

[Kobus Jooste]

Having scratched around in my stash of materials, I think I may have found enough galvanised steel tubing to get the bottom carrier frames done in it.  That will leave me with the inner water line and PVC "greenhouse" top section of the frame still to cost.  Busy hunting for the ideal vessel to use as the sump next to the fish tank to pump the water from.  Design coming together nicely.

[Kobus Jooste]

Apart from the "free" steel I have decided to go with a slightly larger sump than originally planned to incorporate another freebie - an ex-swimming pool filter body I kept when it cracked along the top o-ring.  I cut a slightly larger aperture into the top to take out all the cracks, and gutted the pool fittings out.  Now I have a large circular body with two holes in a perfect position to make a swirl filter.  It will (kind of) fit in next to the FT.  Next step is to sink it in next to the FT at the right level, and fit the plumbing.  Now to scrounge the bits I need for the bucket filter box.............

[Bob Segraves-Collis]

Greetings Kobus, these should work well.  I was considering using the basic pipe, inner spray tube and nozzle arrangement in a tower set up using 6" rectangular tubes with my net pots set on two adjacent faces.  The net pots would be set at angle much the same as the grow station you have in your tower design.  Using the rectangular tubes I think I can get decent spray dispersion suited to plants on two faces of the towers.

[Kobus Jooste]

Thanks for the feedback.  I am yet to get around to making the changes (winter here), but am looking forward to trying the set-up.

Bob Segraves-Collis said:

Greetings Kobus, these should work well.  I was considering using the basic pipe, inner spray tube and nozzle arrangement in a tower set up using 6" rectangular tubes with my net pots set on two adjacent faces.  The net pots would be set at angle much the same as the grow station you have in your tower design.  Using the rectangular tubes I think I can get decent spray dispersion suited to plants on two faces of the towers.

[steve]

Kobus, It didn't seem like enough space in a 4 in. pipe for another smaller tube. Especially if it has to spray on the roots. A 6 in pipe would be better but they are spendy here. I drilled holes in and inserted Tee with drilled pipe cap to spray in between every other plant for aeration. It was a pain but seemed like the thing to do to get the air. Allow for easy maintenance for me if i need to clean. attached pic.

[Kobus Jooste]

Anything larger than 4 inch is very expensive here too.  I was planning to go for much smaller pot spaces though - 2 inch or max 3 inch net pots for lettuce only.  then I planned to use 3/4 inch pipe internally for the water spray.  I have not gotten round to doing any of it as I am first messing with the layout of my existing space and adding towers.  I really do not want to grow anything larger than a lettuce in there.

steve said:

Kobus, It didn't seem like enough space in a 4 in. pipe for another smaller tube. Especially if it has to spray on the roots. A 6 in pipe would be better but they are spendy here. I drilled holes in and inserted Tee with drilled pipe cap to spray in between every other plant for aeration. It was a pain but seemed like the thing to do to get the air. Allow for easy maintenance for me if i need to clean. attached pic.

[Averan]

Kobus, since you are looking for an economical method for NFT, have you considered using corrugated drainage pipe?  There was an article in BYAP magazine about growing strawberries this way.  The didn't use any misters or internal spray pipe, just a timed flow into 4" corrugated drain pipe.  The plants were held inside cut pieces of 2" pvc instead of net pots.  Each pot-tube was inserted into a hole in the 4" until it touched the bottom.  The corrugation ensures that there is space open at the bottom for roots to grow out of and for water to pass by.  The plants need to have just enough root mass so that it is long enough to reach the water running along the bottom of the pipe.

Check out my related post here: http://aquaponicscommunity.com/xn/detail/4778851:Comment:142318

[Kobus Jooste]

Averan - thanks for the link.  As you can see from my designs, I already employ both vertical and horizontal 4 inch pipes.  Those flexible ones in the pic is great, but I have not seen them here in a store as yet.  I like the different set-ups in use and want to learn about as many different ones as possible.  I use towers for smaller plants, and at the moment, my oppinion is that I can get more milage out of vertical towers in terms of meters of pipe used than with horizontal, although the horizontal is easier to set up.  The cutting and shaping is easy once you get into it though.

 

For my system, I am working towards gravel bed filtration and then using my space the best - vertically and horizontally. 

 

Thanks again for the link and welcome to the group. 

Averan said:

Kobus, since you are looking for an economical method for NFT, have you considered using corrugated drainage pipe?  There was an article in BYAP magazine about growing strawberries this way.  The didn't use any misters or internal spray pipe, just a timed flow into 4" corrugated drain pipe.  The plants were held inside cut pieces of 2" pvc instead of net pots.  Each pot-tube was inserted into a hole in the 4" until it touched the bottom.  The corrugation ensures that there is space open at the bottom for roots to grow out of and for water to pass by.  The plants need to have just enough root mass so that it is long enough to reach the water running along the bottom of the pipe.

Check out my related post here: http://aquaponicscommunity.com/xn/detail/4778851:Comment:142318

[Kobus Jooste]

Hi all.  This original design is not going to find a place in my system for now, but it did inspire some internal changes to my towers.  I am messing around with media (coir) filled towers on timer and so far, it seem to work well.  One issue was water distribution though.  I could not get a nice distribution of water flow through the tower with a single 20 mm delivery point (plus too much water went into a single tower, making the amount of plants that I could stick in there on the filtered water line a little limited.

 

So into the top of each compact tower (there are no plants at the back, just 8 plants per tower) is a spray head made out of standard pvc fittings.  Water distribution is quite even and the flow needed to power these 4 are only about 30% more than what came into the trial tower via a unrestricted 20 mm elbow.  I am hoping to be able to run 8 - 10 of these towers in the back of my greenhouse off the single filtered water line and a 60 Watt pump (consider that the water has to be lifted almost 3 m to the top of the tower line).

 

 

I am still experimenting with the set-up thus it is not all plumbed up, but I think this will be a nice eddition to the back of the system - using those vertical spaces for another 50 - 60 plants.