Wicking bed design

[Chris Smith]

We have been growing root crops and everything else in our wicking beds with great success. We would like to discuss designs of beds and their operation in this discussion.

[Chris Smith]

Tim's description of our wicking beds is not accurate. We do not use the overflow from the sump to water the beds. We water the beds as needed via a small pump that is flopped into the closeted trough and used top off the reservoirs.

Larry Yonashiro said:

Chris, your design was featured in one of Tim's newsletters a few months ago, and its been in the back of my mind ever since.  I was thinking of plumbing the wicking bed system to my green tilapia growout tank by connecting the feed line to the rock water reservoir under the growing media and capturing the overflow to a sump tank for return to the fish tank.  This would keep the water reservoir at a constantly full level.  This may not be desirable as the growing media may need to periodically dry out for optimal root growth.  But I was planning to test this out anyway.  The moisture content of the growing media could possibly be controlled by varying its depth to compensate for the constantly full water reservoir below.

Another design option could be to put a timer on a pump to feed the rock media to control the growing media dry out time.  In this case, a return sump tank may not be necessary because the volume of return water may be insignificant.  The overflow can simply be diverted to water ground based plants (Side note: Bill, as you know, fish water has poo in it, and should work as media fertilizer.  My worms love it, and my ground based plants love it).  This would also act as a periodic water change for my green tank as I would have to top it off it with clean water. 

I dunno, as with anything, the proof is in the pudding, and Chris, you're making pudding.  I still need to test it out.  Thanks again for sharing.

[Chris Smith]

Aloha Paul,

I would like to see some pictures of your systems. Our wicking beds are experiments that we are continuing to fine tune and we are looking for more ideas. We have no need for sensors other than our observation on a regular basis.

As for the fish and nitrification it happens everywhere in the systems. The bacteria is everywhere in the systems from the water column, the media , the sides of the troughs and in the coir. When we add solids from the settling tank to the wicking beds we are not only adding nutrient but the nitrification bacteria as well. We prevent sunlight from hitting the system water to keep algae to a minimum.

Paul Smith said:

Hi Chris,

Your system sounds a lot like a enlarged Earthbox Growing system. http://www.earthbox.com/

You might be able to go on to the site above and get water level sensors for your barrels.

I have been using a similar system, using half whisky barrels for years.  The only difference is,

I just used tap water for moisture. 

I inverted the cut-off bottom of a rope-handled bin in the bottom of the whiskey/wine barrel.

I drilled a hole in the center of my inverted pan to allow for a water tube.  Instead of recovering the

water, I drilled a hole in the side of the whiskey/wine barrel at the level of the top of the inverted

pan. When I watered, usually every 3 days, I let the water run until it ran out of the side drain hole.

I filled the barrel with grow medium and planted usually tomatoes and other plants. A half whiskey/wine

barrel would last about 8 to 10 years.

I can see where using the used vermicasting soil would be a great advantage.  I could have used

the same system using fish water and recovering it back through a filter to the fish tank.

Here is the advantage of your cinder.  It performs the filter function for you without having to resort

to a seperate filter bed.

Do you grow your fish in a dark enough environment to allow the nitrites to be changed to nitrates

in the fish tank or do you allow this to happen in the settling tank?

[Paul Smith]

Hi Chris,

Unfortunately, I have just moved from where i was using the oak barrels.  I will try to make a sketch of the systems I had built.

Currently, I am in the start-up stage in my new home.  It will take a couple of years to get it all up and running; funding, funding.

One thing I do have at my new home is a fish pond.  This pond by itself is a pain in the ---, but I can sure use it as a source for fish pooey water; and create some grow beds with food for the family.

One point I want some clarification on.  You use a wicking system to get moisture to your plants.  This doesn't furnish any more nutrients to the plants, except for the rich media you have provided from the vermicompost.  I read where you do overcast nutrient rich fish poo and sludge from your clarifier tank.

If I were to use a wicking system as you described, or one similar to the one I used with the oak barrels, I would have to supply supplementary nutrients  to my grow media, especially during the final stages of production.

This is what the folks at Earthbox do with the fertilizer strip down the middle of their box.  They also utilize a plastic cover over the box with cut-outs for the plants.  The sun heats the plastic and grow media causing evaporation and condensation on the underside of the plastic cover; which drips through the fertilizer strip into the grow media.

I suppose I could do the same thing by providing a constant drip of nutrient rich water just under the cover, through the media, down through the filter layer and back to the fish pond.  I could use foam rafts for this purpose.

Wow, always many ways to approach solutions.  I guess I will just have to set up something, experiment and see.

Have a Fantastic Day!!

Paul.

[Rob Nash]

Chris, do you think I could get away with only 4 inches of gravel zone on a flow through design, using ap water? I have some old aeroponic tubes that are about 12inches deep, and they have fill and drain at about 4 inches… ill post some pics.

[Pavel Zeman]

This is awesome Chris. Thanks for the pictures.

I have over 100 Small Papaya Starts grown from seeds that are still in the trough (I gave some to Larry too) that I will have to move into a wicking container in the next few weeks.

I was thinking 5 gallon buckets, but those could tip over eventually as the tree gets 5'+ tall, the barrels (with multiple plants in each) are going to be better.

If it only needs to be watered once a week, timer and the extra plumbing might be overkill.

Maybe I will just water with the system water manually and top it off as needed.

If the water can't last for a week, I could regulate that further by using 3"+ stand pipe, rather than just the 2'-3' long 2" pipe.

That's a lot of coir there - how many bags of coir do you run through per month? :)

I see a source for barrels here for $15 a piece, so I will try this out and report back.

[Chris Smith]

Rob, your tubes should work fine. You will be limited to growing root crops that need less than 8 inches. Some of the longer carrots in my last barrel grew down to the bottom of the media(12 inches deep) and grew through the mat. When I harvested them they broke off at the mat.The shorter carrots should work fine. So far I am having good results with spinach which is a crop that I have struggled to grow well in AP for many years.

Rob Nash said:

Chris, do you think I could get away with only 4 inches of gravel zone on a flow through design, using ap water? I have some old aeroponic tubes that are about 12inches deep, and they have fill and drain at about 4 inches… ill post some pics.

[Chris Smith]

Coir is pretty much inert and will not provide any nutritional value to plants. The AP water has nutrients for the plants to grow and will without any additional supplements. I add castings and settling tank water to be beds because I have them and it seems to make the plants grow a little faster. My first bed used nothing but coir and system water and worked just fine!
Paul Smith said:

Hi Chris,

Unfortunately, I have just moved from where i was using the oak barrels.  I will try to make a sketch of the systems I had built.

Currently, I am in the start-up stage in my new home.  It will take a couple of years to get it all up and running; funding, funding.

One thing I do have at my new home is a fish pond.  This pond by itself is a pain in the ---, but I can sure use it as a source for fish pooey water; and create some grow beds with food for the family.

One point I want some clarification on.  You use a wicking system to get moisture to your plants.  This doesn't furnish any more nutrients to the plants, except for the rich media you have provided from the vermicompost.  I read where you do overcast nutrient rich fish poo and sludge from your clarifier tank.

If I were to use a wicking system as you described, or one similar to the one I used with the oak barrels, I would have to supply supplementary nutrients  to my grow media, especially during the final stages of production.

This is what the folks at Earthbox do with the fertilizer strip down the middle of their box.  They also utilize a plastic cover over the box with cut-outs for the plants.  The sun heats the plastic and grow media causing evaporation and condensation on the underside of the plastic cover; which drips through the fertilizer strip into the grow media.

I suppose I could do the same thing by providing a constant drip of nutrient rich water just under the cover, through the media, down through the filter layer and back to the fish pond.  I could use foam rafts for this purpose.

Wow, always many ways to approach solutions.  I guess I will just have to set up something, experiment and see.

Have a Fantastic Day!!

Paul.

[Chris Smith]

Paul, Papayas are a very long tern crop that will need ample space and consume lots of water when mature. You might consider using an in ground wicking bed and fertilize with AP water, Here is a great PDF on wicking bed technology for soil growing.

Pavel Zeman said:

This is awesome Chris. Thanks for the pictures.

I have over 100 Small Papaya Starts grown from seeds that are still in the trough (I gave some to Larry too) that I will have to move into a wicking container in the next few weeks.

I was thinking 5 gallon buckets, but those could tip over eventually as the tree gets 5'+ tall, the barrels (with multiple plants in each) are going to be better.

If it only needs to be watered once a week, timer and the extra plumbing might be overkill.

Maybe I will just water with the system water manually and top it off as needed.

If the water can't last for a week, I could regulate that further by using 3"+ stand pipe, rather than just the 2'-3' long 2" pipe.

That's a lot of coir there - how many bags of coir do you run through per month?

I see a source for barrels here for $15 a piece, so I will try this out and report back.

[Paul Smith]

Hi Chris,

Thanks for the below ground wicking bed link.  I will be able to use this technique in my landscape.

All of my food growing beds will be above ground wicking beds, using the techniques I am

learning about here.

Paul.

[Dino Zucchi]

I am really happy to find this forum there is not much info on wicking beds. I found a few videos and a few web pages but no info on using aquaponic water or fish pond water.

I hope some one can answer a few of my questions I am currently building a 3x10 wicking bed in DC.

1. I have a koi fish pond with a UV light the water is crystal clear. Do you think I could just pour this water into the wicking reservoir and that woudl be enough fertilizer for the plants? wont the Fish emulsion sink and sit at the bottom and not fertilize the plant roots?

2. What is the best growing medium? chris you say 100% coir?

3. does anyone have any other Soil Recipes for wicking beds, I read that it should be 50% sand?

thanks chris for your hard work.

[Dino Zucchi]

FYI i plan to grow sweet potatos and Kale.

Dino Zucchi said:

I am really happy to find this forum there is not much info on wicking beds. I found a few videos and a few web pages but no info on using aquaponic water or fish pond water.

I hope some one can answer a few of my questions I am currently building a 3x10 wicking bed in DC.

1. I have a koi fish pond with a UV light the water is crystal clear. Do you think I could just pour this water into the wicking reservoir and that woudl be enough fertilizer for the plants? wont the Fish emulsion sink and sit at the bottom and not fertilize the plant roots?

2. What is the best growing medium? chris you say 100% coir?

3. does anyone have any other Soil Recipes for wicking beds, I read that it should be 50% sand?

thanks chris for your hard work.

[Chris Smith]

Dino a uv light will kill nitrifying bacteria we rely on in aquaponics. My system water is clear to look through but a slight tea color from the billions of bacteria in the water column. I cannot say if your water has enough nutrition to fertilize your bed if you are using an inert growing medium like coir. Try testing your water for nitrates. If you have nitrates it should work. I like coir for my carrots because it is a very fine material that allows me to grow perfect shaped carrots and I already had it. It is possible to use soil mixes too. If using soil be sure not to allow any overflow back to your system. I am currently experimenting with organic soil in wicking pots. I will post some pics on that soon.