pvc aggregate media for towers

[Kobus Jooste]

As I stated a long time ago, I have taken an interest in putting together some light weight media for media beds or towers.  Hydroton is way too expensive in South Africa, and I was looking for alternatives to have as media that was lighter than gravel.  A while back I mused about the possibility of getting some pvc granules and experimenting, and then shoved the concept onto the back burner.  As I am now getting ready for spring planting, I'm finishing off some towers and experimenting with media.  Coir is not doing it for me, with the water channeling in the tower far to rapidly and creating uneven water flow and dry patches.

 

So I went back to the pvc granule thinking.  I got hold of some virgin pvc used for injection moulding, and here is my first test run.  I basically heat them to a point where they become sticky, and then cool them rapidly again, resulting in a "peanut brittle" aggregate.  I mix these with vermiculite and use them in te tower to experiment with.  They hold moisture much better, and the flow is better too.  I do not know how much different the weight of the tower is compared to hydroton, but I like the overall effect of moisture retention and surface area creation that this combination gives.  It is a lot cheaper than hydroton too. 

 

 

I have fitted spray heads to all my towers, and the water delivery is good but without washing any of the vermiculite out again.  The tower also stays moist for much longer than what my current flooding cycle is.

[steve]

Hi Kobus, Just a thought wondering if anyone has tried carbon from wood ash. Would be dirty to handle but once in place?

[Kobus Jooste]

Steve - there was a very long discussion here on one of the forums about charcoal and jet stoves and making charcoal media for beds.  I never went that route but a few people experimented with it.  If you search "charcoal" in the forum page you should find the discussion.

[Nate Storey]

Charcoal becomes a net nitrogen consumer, but can work.  These medias must be non-biodegradable, hold little water and be inert, or the purpose is defeated.

[Chris Smith]

I just had to dump a 6 month old tower planted with strawberries and used cinder as media. The tower became so root bound that water was not flowing down properly. It got to the point that water was exiting the second set of holes, dripping down the strawberry leaves and out of the system. The tower was so root bound that it took me over an hour to dislodge all the roots and media in a 4 foot length.

I have now gone back to an old idea of mine. I am calling it aquaeroponics. Basically I am doing aeroponic towers now to make them lighter and easier to change out plants. A little more time and detail is needed in the construction process to eliminate any light from entering the tower but the trade off is no media and easy plant removal.

[Harold Sukhbir]

Hi Kobus,

Yes its lightweight. Can you estimate the cost of 50lbs of your vermiculite/pvc/hydroton? So you can compare the price?

I know It will work in the towers but can you see a translation to beds with this? Otherwise this is good thinking Kobus!

[Kobus Jooste]

OK - replying to all at once.

 

Harold - I was in too much of a hurry to get the first tower up to weigh how much material went in, but I paid around $1.70 per kilo for the pvc and about the same for half a kilo of vermiculite.  Both were sourced from standard resale and not wholesale.  I will weigh the material of the second tower but it does not take all that much.  The last time I priced hydroton here was too long ago to remember the exact details but I will let you know soon.

 

Chris - I plan to do short rotation greens in these towers although I was also thinking strawberries...... The towers are "push fit" and I plan to take them apart between crop rotations. 

[Chris Smith]

Eliminating media saves the expense of media and the labor to clean it. The plants seem to grow a little fasted too. All my designs are evolving to save me money and time. Worms in the media has helped to keep it clean for the short term crops.

[Kobus Jooste]

Then I assume you will be swirching to constant flow to accomodate plants in aeroponics?  I use media-less horizontal tubes with constant and timed flow at the moment, but nothing vertical without media

Chris Smith said:

Eliminating media saves the expense of media and the labor to clean it. The plants seem to grow a little fasted too. All my designs are evolving to save me money and time. Worms in the media has helped to keep it clean for the short term crops.

[Chris Smith]

Yes and no. In my terraced system I have a constant flow that is falling down hill and I still have lots of room to add vertical grow space without any extra power consumption. I really like the idea of less expense/less labor and it seems to be growing faster.

In my small barrel systems I will continue to use media but grow shorter term crops. In these systems I will rely on worms to consume roots so I don't have to clean media of roots after a harvest.

 

It seems that we are on opposite schedules. We are always communicating in my morning or night. What time is it in South Africa? Here it is 9:25 PM. Good night.

[Harold Sukhbir]

Hi Chris,

Wow! Its 3.45am here. Like to do work at this time, its quiet.

 

[Kobus Jooste]

Chris - we are about 12 hours apart by the looks of things - mid morning here now

 

[Harold Sukhbir]

Hi Chris any chance you can upload a pic? I know we won't be able to see the internals but nevertheless.............

Chris Smith said:

Eliminating media saves the expense of media and the labor to clean it. The plants seem to grow a little fasted too. All my designs are evolving to save me money and time. Worms in the media has helped to keep it clean for the short term crops.