Thoughts on recirculating wicking / sub-irrigated grow tower

[Robert Jack Meyer]

Hey folks,

I'm new to aquaponics, only having dabbled in it briefly before, and am considering my system options.  After much research and brainstorming, I've come up with an idea that I am not entirely sure will work.  The primary inspiration for this idea was the following video:

http://youtu.be/FBh1fjMqjmI

As you could probably guess, my idea is to hook this system up to an aquaponics system, with continuous flow.  Two modifications I would make from the video is decreasing the size and increasing the number of holes on the bucket, down to 1", spaced 1" between each hole, offset between rows, for a total of 70 holes per bucket.  I could also vary the hole size and spacing depending on the crop, but small holes closely spaced would allow intensive production of various high value crops like baby greens, baby spinach, etc.  I would also have the overflow hole in the bottom side of the upper grow bucket, which would attach it securely to the bottom reservoir, and allow the bottom few inches of soil to really get soaked, allowing greater wicking throughout the bucket.  This may even enable me to eliminate the need for a cloth wick, as the video calls for.  Obviously this means the need for some sort of screen material to prevent soil from being washed into the system, for which I was considering using 5 gallon paint strainers, which are also readily available and fit perfectly into the bucket, and also double to hold the soil and seedlings in the holes a bit better.  Here's a diagram I made, very roughly done:

The idea here would be to plant each of these with seedlings of baby lettuce mix, mesclun mix, baby spinach, radishes, scallions, and various herbs, and then stack them up to 4 high, each with it's own reservoir, thus maximizing growing space.  The great part about this idea is that 5 gallon buckets are readily available for free from local bakeries and delis, and the actual parts are probably less than $1/bucket, making it a very economical option. 

I guess the only concern I have is whether it will actually function properly, whether the plants will grow well in this set up, and whether they would filter the water enough.  I'd like to have other types of grow beds as well, so if it isn't sufficient filtering, that's not such a problem, and only a bonus in my opinion.  At the very least I would imagine it would help to filter out the solids to an extent.  Even if it doesn't work out with aquaponics, it would be cool to have sub-irrigated towers made from readily available materials.

So anyone have any thoughts on this?  Would it work, or totally fail?  Any suggestions for modifications to make it function better overall?  I'd love to hear any ideas anyone has!

[Paul Smith]

Hi Robert,
I have some soil wicking boxes set up in my aquaponic system.  They do very well.  One point I would make is, that You drain Your water out of the bucket thoroughly.  I have found that if I try to retain water, the soil gets too wet.

[Robert Jack Meyer]

Good info, thanks for sharing, and great looking set up!  So you think it would be better to have a wicking material, like natural or synthetic rope, or torn up cotton strips, to wick water up into the soil, rather than having the water seep into the soil at all?  How exactly are your planters designed, and do you have them hooked up to an AP system?  How well do the planters filter the water?

[Paul Smith]

Here is a link to an aquaponic system that does what I do.  I came up with my boxes before I discovered this site.

http://www.oldworldaquafarm.com/

The tall pipe at the back of the box is the inlet pipe, with the outlet in the front.  These boxes were built as stand alone boxes, where I manually watered through the tall inlet pipe.  The biggest change, from a 1" inlet pipe, designed to accept the end of a garden hose, to a 3/4" inlet. (I use a 3/4" supply line from my pond. The outlet on the stand alone boxes is 1/2", and is located at the top of the water-soil divider to make sure I keep adequate water in the wicking reservoir.
I am moving the outlet drain to the very bottom of the box so I get good water flow and enlarging it to 1"  I have learned that if I keep too much water in the water reservoir, the soil gets too wet.  
I use a landscape fabric barrier between the soil and the water reservoir to prevent soil from getting to my fish pond.
I have used both a synthetic wick and a soil wick.  I believe the soil wick is better because I don't have to worry about the chemical composition of the synthetic wick.  In my experience, the soil does just fine.
In the picture below, You can see the soil wick pocket I have built into the box.  The yellow sheet is the center portion of the lid You see in the upper photo.
The difference between this box and the aquaponic box is the landscape barrier goes all the way across the bottom and up the sides, totally isolating the soil from the auaponic water.

[Paul Smith]

Here is a Youtube video on a kiddy wading pool grow system that would be easy for you to set up.
These pools sell for between $9 and $15, depending upon where You buy them.

Larry recommends that You use fabric plant pouches because the plant roots air prune and don't get root bound.

You could make a 3/4" inlet and an 1 1/4" outlet and circulate Your aquaponic water through the pool.

I would suggest that You add some volcanic rock around the plant bags, and apply a plastic cover over the water to avoid problems with algae.
https://www.youtube.com/watch?v=l_7Cc4xofsI

[Paul Smith]

Here is a description of the boxes.